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King KA, Benton AH, Caudill MT, Stoyanof ST, Kang L, Michalak P, Lahmers KK, Dunman PM, DeHart TG, Ahmad SS, Jutras BL, Poncin K, De Bolle X, Caswell CC. Post-transcriptional control of the essential enzyme MurF by a small regulatory RNA in Brucella abortus. Mol Microbiol 2024; 121:129-141. [PMID: 38082493 DOI: 10.1111/mmi.15207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 11/22/2023] [Accepted: 11/25/2023] [Indexed: 01/15/2024]
Abstract
Brucella abortus is a facultative, intracellular, zoonotic pathogen that resides inside macrophages during infection. This is a specialized niche where B. abortus encounters various stresses as it navigates through the macrophage. In order to survive this harsh environment, B. abortus utilizes post-transcriptional regulation of gene expression through the use of small regulatory RNAs (sRNAs). Here, we characterize a Brucella sRNAs called MavR (for MurF- and virulence-regulating sRNA), and we demonstrate that MavR is required for the full virulence of B. abortus in macrophages and in a mouse model of chronic infection. Transcriptomic and proteomic studies revealed that a major regulatory target of MavR is MurF. MurF is an essential protein that catalyzes the final cytoplasmic step in peptidoglycan (PG) synthesis; however, we did not detect any differences in the amount or chemical composition of PG in the ΔmavR mutant. A 6-nucleotide regulatory seed region within MavR was identified, and mutation of this seed region resulted in dysregulation of MurF production, as well as significant attenuation of infection in a mouse model. Overall, the present study underscores the importance of sRNA regulation in the physiology and virulence of Brucella.
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Affiliation(s)
- Kellie A King
- Department of Biomedical Sciences and Pathobiology, Center for One Health Research, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, USA
| | - Angela H Benton
- Department of Biomedical Sciences and Pathobiology, Center for One Health Research, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, USA
| | - Mitchell T Caudill
- Department of Biomedical Sciences and Pathobiology, Center for One Health Research, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, USA
| | - S Tristan Stoyanof
- Department of Biomedical Sciences and Pathobiology, Center for One Health Research, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, USA
| | - Lin Kang
- Department of Biomedical Sciences, Edward Via College of Osteopathic Medicine, Monroe, Louisiana, USA
- College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana, USA
- Center for One Health Research, Edward Via College of Osteopathic Medicine, Blacksburg, Virginia, USA
| | - Pawel Michalak
- Department of Biomedical Sciences, Edward Via College of Osteopathic Medicine, Monroe, Louisiana, USA
- Center for One Health Research, Edward Via College of Osteopathic Medicine, Blacksburg, Virginia, USA
- Institute for Evolution, University of Haifa, Haifa, Israel
| | - Kevin K Lahmers
- Department of Biomedical Sciences and Pathobiology, Center for One Health Research, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, USA
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, USA
| | - Tanner G DeHart
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA
| | - Saadman S Ahmad
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA
| | - Brandon L Jutras
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA
| | - Katy Poncin
- URBM, Narilis, University of Namur, Namur, Belgium
| | | | - Clayton C Caswell
- Department of Biomedical Sciences and Pathobiology, Center for One Health Research, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, USA
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Piraino L, Chen CY, Mereness J, Dunman PM, Ovitt C, Benoit D, DeLouise L. Identifying novel radioprotective drugs via salivary gland tissue chip screening. bioRxiv 2023:2023.07.12.548707. [PMID: 37503292 PMCID: PMC10369976 DOI: 10.1101/2023.07.12.548707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
During head and neck cancer treatment, off-target ionizing radiation damage to the salivary glands commonly causes a permanent loss of secretory function. Due to the resulting decrease in saliva production, patients have trouble eating, speaking and are predisposed to oral infections and tooth decay. While the radioprotective antioxidant drug Amifostine is approved to prevent radiation-induced hyposalivation, it has intolerable side effects that limit its use, motivating the discovery of alternative therapeutics. To address this issue, we previously developed a salivary gland mimetic (SGm) tissue chip platform. Here, we leverage this SGm tissue chip for high-content drug discovery. First, we developed in-chip assays to quantify glutathione and cellular senescence (β-galactosidase), which are biomarkers of radiation damage, and we validated radioprotection using WR-1065, the active form of Amifostine. Following validation, we tested other reported radioprotective drugs, including, Edaravone, Tempol, N-acetylcysteine (NAC), Rapamycin, Ex-Rad, and Palifermin, confirming that all drugs but NAC and Ex-Rad exhibited robust radioprotection. Next, a Selleck Chemicals library of 438 FDA-approved drugs was screened for radioprotection. We discovered 25 hits, with most of the drugs identified with mechanisms of action other than antioxidant activity. Hits were down-selected using EC 50 values and pharmacokinetics and pharmacodynamics data from the PubChem database leading to testing of Phenylbutazone (anti-inflammatory), Enoxacin (antibiotic), and Doripenem (antibiotic) for in vivo radioprotection in mice using retroductal injections. Results confirm that Phenylbutazone and Enoxacin exhibited equivalent radioprotection to Amifostine. This body of work demonstrates the development and validation of assays using a SGm tissue chip platform for high-content drug screening and the successful in vitro discovery and in vivo validation of novel radioprotective drugs with nonantioxidant primary indications pointing to possible, yet unknown novel mechanisms of radioprotection.
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Young M, Chojnacki M, Blanchard C, Cao X, Johnson WL, Flaherty D, Dunman PM. Genetic Determinants of Acinetobacter baumannii Serum-Associated Adaptive Efflux-Mediated Antibiotic Resistance. Antibiotics (Basel) 2023; 12:1173. [PMID: 37508269 PMCID: PMC10376123 DOI: 10.3390/antibiotics12071173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/05/2023] [Accepted: 07/06/2023] [Indexed: 07/30/2023] Open
Abstract
Acinetobacter baumannii is a nosocomial pathogen of serious healthcare concern that is becoming increasingly difficult to treat due to antibiotic treatment failure. Recent studies have revealed that clinically defined antibiotic-susceptible strains upregulate the expression of a repertoire of putative drug efflux pumps during their growth under biologically relevant conditions, e.g., in human serum, resulting in efflux-associated resistance to physiologically achievable antibiotic levels within a patient. This phenomenon, termed Adaptive Efflux Mediated Resistance (AEMR), has been hypothesized to account for one mechanism by which antibiotic-susceptible A. baumannii fails to respond to antibiotic treatment. In the current study, we sought to identify genetic determinants that contribute to A. baumannii serum-associated AEMR by screening a transposon mutant library for members that display a loss of the AEMR phenotype. Results revealed that mutation of a putative pirin-like protein, YhaK, results in a loss of AEMR, a phenotype that could be complemented by a wild-type copy of the yhaK gene and was verified in a second strain background. Ethidium bromide efflux assays confirmed that the loss of AEMR phenotype due to pirin-like protein mutation correlated with reduced overarching efflux capacity. Further, flow cytometry and confocal microscopy measures of a fluorophore 7-(dimethylamino)-coumarin-4-acetic acid (DMACA)-tagged levofloxacin isomer, ofloxacin, further verified that YhaK mutation reduces AEMR-mediated antibiotic efflux. RNA-sequencing studies revealed that YhaK may be required for the expression of multiple efflux-associated systems, including MATE and ABC families of efflux pumps. Collectively, the data indicate that the A. baumannii YhaK pirin-like protein plays a role in modulating the organism's adaptive efflux-mediated resistance phenotype.
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Affiliation(s)
- Mikaeel Young
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA; (M.Y.); (M.C.); (W.L.J.)
| | - Michaelle Chojnacki
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA; (M.Y.); (M.C.); (W.L.J.)
| | - Catlyn Blanchard
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA; (M.Y.); (M.C.); (W.L.J.)
| | - Xufeng Cao
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University College of Pharmacy, Lafayette, IN 47907, USA
| | - William L. Johnson
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA; (M.Y.); (M.C.); (W.L.J.)
| | - Daniel Flaherty
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University College of Pharmacy, Lafayette, IN 47907, USA
- Purdue Institute for Drug Discovery, West Lafayette, IN 47907, USA
- Purdue Institute of Inflammation, Immunology and Infectious Disease, West Lafayette, IN 47907, USA
| | - Paul M. Dunman
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA; (M.Y.); (M.C.); (W.L.J.)
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Young M, Walsh DJ, Masters E, Gondil VS, Laskey E, Klaczko M, Awad H, McGrath J, Schwarz EM, Melander C, Dunman PM. Identification of Staphylococcus aureus Penicillin Binding Protein 4 (PBP4) Inhibitors. Antibiotics (Basel) 2022; 11:antibiotics11101351. [PMID: 36290009 PMCID: PMC9598407 DOI: 10.3390/antibiotics11101351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 09/28/2022] [Accepted: 09/30/2022] [Indexed: 11/16/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a global healthcare concern. Such resistance has historically been attributed to the acquisition of mecA (or mecC), which encodes an alternative penicillin binding protein, PBP2a, with low β-lactam affinity. However, recent studies have indicated that penicillin binding protein 4 (PBP4) is also a critical determinant of S. aureus methicillin resistance, particularly among community-acquired MRSA strains. Thus, PBP4 has been considered an intriguing therapeutic target as corresponding inhibitors may restore MRSA β-lactam susceptibility. In addition to its role in antibiotic resistance, PBP4 has also recently been shown to be required for S. aureus cortical bone osteocyte lacuno-canalicular network (OLCN) invasion and colonization, providing the organism with a niche for re-occurring bone infection. From these perspectives, the development of PBP4 inhibitors may have tremendous impact as agents that both reverse methicillin resistance and inhibit the organism’s ability to cause chronic osteomyelitis. Accordingly, using a whole-cell high-throughput screen of a 30,000-member small molecule chemical library and secondary assays we identified putative S. aureus PBP4 inhibitors. Quantitative reverse transcriptase mediated PCR and PBP4 binding assays revealed that hits could be further distinguished as compounds that reduce PBP4 expression versus compounds that are likely to affect the protein’s function. We also showed that 6.25 µM (2.5 µg/mL) of the lead candidate, 9314848, reverses the organism’s PBP4-dependent MRSA phenotype and inhibits its ability to traverse Microfluidic-Silicon Membrane-Canalicular Arrays (µSiM-CA) that model the OLCN orifice. Collectively, these molecules may represent promising potential as PBP4-inhibitors that can be further developed as adjuvants for the treatment of MRSA infections and/or osteomyelitis prophylactics.
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Affiliation(s)
- Mikaeel Young
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Danica J. Walsh
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Elysia Masters
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Vijay Singh Gondil
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Emily Laskey
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Michael Klaczko
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA
| | - Hani Awad
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY 14642, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA
| | - James McGrath
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA
| | - Edward M. Schwarz
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY 14642, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
- Correspondence: (C.M.); (P.M.D.); Tel.: +1-574-631-9036 (C.M.); +1-585-276-5700 (P.M.D.)
| | - Paul M. Dunman
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA
- Correspondence: (C.M.); (P.M.D.); Tel.: +1-574-631-9036 (C.M.); +1-585-276-5700 (P.M.D.)
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Mei JA, Johnson W, Kinn B, Laskey E, Nolin L, Bhamare P, Stalker C, Dunman PM, Wozniak RAF. Antimicrobial Activity of a Triple Antibiotic Combination Toward Ocular Pseudomonas aeruginosa Clinical Isolates. Transl Vis Sci Technol 2022; 11:26. [PMID: 35612831 PMCID: PMC9145016 DOI: 10.1167/tvst.11.5.26] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Purpose Pseudomonas aeruginosa is a leading cause of corneal infections. Recently, we discovered an antimicrobial drug combination, polymyxin B/trimethoprim (PT) + rifampin, that displayed impressive efficacy toward P. aeruginosa in both in vitro and in vivo studies. As such, this combination was further evaluated as a potential keratitis therapeutic through testing the combination's efficacy against a diverse set of P. aeruginosa clinical isolates. Methods Minimum inhibitory concentrations (MICs) of moxifloxacin, levofloxacin, erythromycin, tobramycin, PT, polymyxin B (alone), trimethoprim (alone), and rifampin were determined for 154 ocular clinical P. aeruginosa isolates, 90% of which were derived from corneal scrapings. Additionally, the efficacy of PT + rifampin was evaluated utilizing fractional inhibitory concentration (FIC) testing. Results While 100% of isolates were resistant to erythromycin (average MIC 224 ± 110 µg·mL−1) and trimethoprim (alone) (206 ± 67.3 µg·mL−1), antibiotic resistance was generally found to be low: moxifloxacin (2% of isolates resistant; average MIC 1.08 ± 1.61 µg·mL−1), levofloxacin (3.9%; 1.02 ± 2.96 µg·mL−1), tobramycin (1%; 0.319 ± 1.31 µg·mL−1), polymyxin B (0%; 0.539 ± 0.206 µg·mL−1), PT (0%; 0.416 ± 0.135 µg·mL−1), and rifampin (0%; 23.4 ± 6.86 µg·mL−1). Additionally, FIC testing revealed that PT + rifampin eradicated 100% of isolates demonstrating additive or synergistic activity in 95% of isolates (average FIC index 0.701 ± 0.132). Conclusions The drug combination of PT + rifampin was effective against a large panel of clinically relevant P. aeruginosa strains and, as such, may represent a promising therapeutic for P. aeruginosa keratitis. Translational Relevance This work furthers the preclinical development of a novel antibiotic combination for the treatment of corneal infections (bacterial keratitis).
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Affiliation(s)
- Jia A Mei
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - William Johnson
- Department of Ophthalmology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Bailey Kinn
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Emily Laskey
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Lydia Nolin
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Pratham Bhamare
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Charlotte Stalker
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Rachel A F Wozniak
- Department of Ophthalmology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
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Johnson WL, Sohn MB, Taffner S, Chatterjee P, Dunman PM, Pecora N, Wozniak RAF. Genomics of Staphylococcus aureus ocular isolates. PLoS One 2021; 16:e0250975. [PMID: 33939761 PMCID: PMC8092774 DOI: 10.1371/journal.pone.0250975] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 04/16/2021] [Indexed: 02/02/2023] Open
Abstract
Staphylococcus aureus is a major cause of ocular infections, often resulting in devastating vision loss. Despite the significant morbidity associated with these infections, little is yet known regarding the specific strain types that may have a predilection for ocular tissues nor the set of virulence factors that drive its pathogenicity in this specific biological niche. Whole genome sequencing (WGS) can provide valuable insight in this regard by providing a prospective, comprehensive assessment of the strain types and virulence factors driving disease among specific subsets of clinical isolates. As such, a set of 163-member S. aureus ocular clinical strains were sequenced and assessed for both common strain types (multilocus sequence type (MLST), spa, agr) associated with ocular infections as well as the presence/absence of 235 known virulence factors in a high throughput manner. This ocular strain set was then directly compared to a fully sequenced 116-member non-ocular S. aureus strain set curated from NCBI in order to identify key differences between ocular and non-ocular S. aureus isolates. The most common sequence types found among ocular S. aureus isolates were ST5, ST8 and ST30, generally reflecting circulating non-ocular pathogenic S. aureus strains. However, importantly, ocular isolates were found to be significantly enriched for a set of enterotoxins, suggesting a potential role for this class of virulence factors in promoting ocular disease. Further genomic analysis revealed that these enterotoxins are located on mobile pathogenicity islands, thus horizontal gene transfer may promote the acquisition of enterotoxins, potentially amplifying S. aureus virulence in ocular tissues.
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Affiliation(s)
- William L. Johnson
- Department of Ophthalmology, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Michael B. Sohn
- Department of Biostatistics and Computational Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Samantha Taffner
- Department of Clinical Microbiology, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Payel Chatterjee
- Department of Ophthalmology, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Paul M. Dunman
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Nicole Pecora
- Department of Clinical Microbiology, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Rachel A. F. Wozniak
- Department of Ophthalmology, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
- * E-mail:
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Yang H, Kundra S, Chojnacki M, Liu K, Fuse MA, Abouelhassan Y, Kallifidas D, Zhang P, Huang G, Jin S, Ding Y, Luesch H, Rohde KH, Dunman PM, Lemos JA, Huigens RW. A Modular Synthetic Route Involving N-Aryl-2-nitrosoaniline Intermediates Leads to a New Series of 3-Substituted Halogenated Phenazine Antibacterial Agents. J Med Chem 2021; 64:7275-7295. [PMID: 33881312 DOI: 10.1021/acs.jmedchem.1c00168] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Pathogenic bacteria demonstrate incredible abilities to evade conventional antibiotics through the development of resistance and formation of dormant, surface-attached biofilms. Therefore, agents that target and eradicate planktonic and biofilm bacteria are of significant interest. We explored a new series of halogenated phenazines (HP) through the use of N-aryl-2-nitrosoaniline synthetic intermediates that enabled functionalization of the 3-position of this scaffold. Several HPs demonstrated potent antibacterial and biofilm-killing activities (e.g., HP 29, against methicillin-resistant Staphylococcus aureus: MIC = 0.075 μM; MBEC = 2.35 μM), and transcriptional analysis revealed that HPs 3, 28, and 29 induce rapid iron starvation in MRSA biofilms. Several HPs demonstrated excellent activities against Mycobacterium tuberculosis (HP 34, MIC = 0.80 μM against CDC1551). This work established new SAR insights, and HP 29 demonstrated efficacy in dorsal wound infection models in mice. Encouraged by these findings, we believe that HPs could lead to significant advances in the treatment of challenging infections.
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Affiliation(s)
- Hongfen Yang
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Shivani Kundra
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, Florida 32610, United States
| | - Michaelle Chojnacki
- Department of Microbiology and Immunology, University of Rochester, Rochester, New York 14642, United States
| | - Ke Liu
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Marisa A Fuse
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32827, United States
| | - Yasmeen Abouelhassan
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Dimitris Kallifidas
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Peilan Zhang
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Guangtao Huang
- Department of Molecular Genetics & Microbiology, College of Medicine, University of Florida, Gainesville Florida 32610, United States
| | - Shouguang Jin
- Department of Molecular Genetics & Microbiology, College of Medicine, University of Florida, Gainesville Florida 32610, United States
| | - Yousong Ding
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Hendrik Luesch
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Kyle H Rohde
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32827, United States
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester, Rochester, New York 14642, United States
| | - José A Lemos
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, Florida 32610, United States
| | - Robert W Huigens
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
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Suigo L, Chojnacki M, Zanotto C, Sebastián-Pérez V, Morghen CDG, Casiraghi A, Dunman PM, Valoti E, Straniero V. Staphylococcus aureus RnpA Inhibitors: Computational-Guided Design, Synthesis and Initial Biological Evaluation. Antibiotics (Basel) 2021; 10:antibiotics10040438. [PMID: 33920000 PMCID: PMC8071009 DOI: 10.3390/antibiotics10040438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/12/2021] [Accepted: 04/12/2021] [Indexed: 11/16/2022] Open
Abstract
Antibiotic resistance is spreading worldwide and it has become one of the most important issues in modern medicine. In this context, the bacterial RNA degradation and processing machinery are essential processes for bacterial viability that may be exploited for antimicrobial therapy. In Staphylococcus aureus, RnpA has been hypothesized to be one of the main players in these mechanisms. S. aureus RnpA is able to modulate mRNA degradation and complex with a ribozyme (rnpB), facilitating ptRNA maturation. Corresponding small molecule screening campaigns have recently identified a few classes of RnpA inhibitors, and their structure activity relationship (SAR) has only been partially explored. Accordingly, in the present work, using computational modeling of S. aureus RnpA we identified putative crucial interactions of known RnpA inhibitors, and we used this information to design, synthesize, and biologically assess new potential RnpA inhibitors. The present results may be beneficial for the overall knowledge about RnpA inhibitors belonging to both RNPA2000-like thiosemicarbazides and JC-like piperidine carboxamides molecular classes. We evaluated the importance of the different key moieties, such as the dichlorophenyl and the piperidine of JC2, and the semithiocarbazide, the furan, and the i-propylphenyl ring of RNPA2000. Our efforts could provide a foundation for further computational-guided investigations.
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Affiliation(s)
- Lorenzo Suigo
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Luigi Mangiagalli 25, 20133 Milano, Italy; (L.S.); (A.C.); (E.V.)
| | - Michaelle Chojnacki
- Department of Microbiology and Immunology, University of Rochester Medical Center, 601 Elmwood Ave., Rochester, NY 14642, USA; (M.C.); (P.M.D.)
| | - Carlo Zanotto
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Via Vanvitelli 32, 20129 Milano, Italy;
| | | | - Carlo De Giuli Morghen
- Department of Chemical—Pharmaceutical and Biomolecular Technologies, Catholic University “Our Lady of Good Counsel”, Rr. Dritan Hoxha, 1025 Tirana, Albania;
| | - Andrea Casiraghi
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Luigi Mangiagalli 25, 20133 Milano, Italy; (L.S.); (A.C.); (E.V.)
| | - Paul M. Dunman
- Department of Microbiology and Immunology, University of Rochester Medical Center, 601 Elmwood Ave., Rochester, NY 14642, USA; (M.C.); (P.M.D.)
| | - Ermanno Valoti
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Luigi Mangiagalli 25, 20133 Milano, Italy; (L.S.); (A.C.); (E.V.)
| | - Valentina Straniero
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Luigi Mangiagalli 25, 20133 Milano, Italy; (L.S.); (A.C.); (E.V.)
- Correspondence: ; Tel.: +39-0250319361
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Scherzi T, D'Ambrosio EA, Daher SS, Grimes CL, Dunman PM, Andrade RB. Staphylococcus aureus resistance to albocycline can be achieved by mutations that alter cellular NAD/PH pools. Bioorg Med Chem 2021; 32:115995. [PMID: 33477021 PMCID: PMC7891091 DOI: 10.1016/j.bmc.2021.115995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 12/31/2020] [Indexed: 11/21/2022]
Abstract
Small molecule target identification is a critical step in modern antibacterial drug discovery, particularly against multi-drug resistant pathogens. Albocycline (ALB) is a macrolactone natural product with potent activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) whose mechanism of action has been elusive to date. Herein, we report biochemical and genomic studies that reveal ALB does not target bacterial peptidoglycan biosynthesis or the ribosome; rather, it appears to modulate NADPH ratios and upregulate redox sensing in the cell consistent with previous studies at Upjohn. Owing to the complexity inherent in biological pathways, further genomic assays are needed to identify the true molecular target(s) of albocycline.
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Affiliation(s)
- Tyler Scherzi
- Department of Microbiology and Immunology, University of Rochester, School of Medicine and Dentistry, Rochester, NY 14642, United States
| | - Elizabeth A D'Ambrosio
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States
| | - Samer S Daher
- Department of Chemistry, Temple University, Philadelphia, PA 19122, United States
| | - Catherine L Grimes
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester, School of Medicine and Dentistry, Rochester, NY 14642, United States
| | - Rodrigo B Andrade
- Department of Chemistry, Temple University, Philadelphia, PA 19122, United States.
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10
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Daher SS, Franklin KP, Scherzi T, Dunman PM, Andrade RB. Synthesis and biological evaluation of semi-synthetic albocycline analogs. Bioorg Med Chem Lett 2020; 30:127509. [PMID: 32827630 DOI: 10.1016/j.bmcl.2020.127509] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 12/18/2022]
Abstract
Albocycline (ALB) is a unique macrolactone natural product with potent, narrow-spectrum activity against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-intermediate (VISA), and vancomycin-resistant S. aureus (VRSA) strains (MIC = 0.5-1.0 μg/mL). Described herein is the synthesis and evaluation of a novel series analogs derived from albocycline by functionalization at three specific sites: the C2-C3 enone, the tertiary carbinol at C4, and the allylic C16 methyl group. Exploration of the structure-activity relationships (SAR) by means of minimum inhibitory concentration assays (MICs) revealed that C4 ester analog 6 was twice as potent as ALB, which represents a class of lead compound that can be further studied to address multi-drug resistant pathogens.
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Affiliation(s)
- Samer S Daher
- Department of Chemistry, Temple University, Philadelphia, PA 19122, United States
| | - Kevin P Franklin
- Department of Chemistry, Temple University, Philadelphia, PA 19122, United States
| | - Tyler Scherzi
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, United States
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, United States
| | - Rodrigo B Andrade
- Department of Chemistry, Temple University, Philadelphia, PA 19122, United States.
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11
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Chojnacki M, Cao X, Young M, Fritz RN, Dunman PM, Flaherty DP. Optimization of 4-Substituted Benzenesulfonamide Scaffold To Reverse Acinetobacter baumannii Serum-Adaptive Efflux Associated Antibiotic Tolerance. ChemMedChem 2020; 15:1731-1740. [PMID: 32681604 DOI: 10.1002/cmdc.202000328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Indexed: 11/11/2022]
Abstract
Acinetobacter baumannii is a nosocomial pathogen of urgent concern for public health due to rising rates of multidrug and pandrug resistance. In the context of environmental cues such as growth in human serum, A. baumannii is known to display adaptive efflux, in which a multitude of efflux-associated genes are upregulated, resulting in efflux-mediated drug tolerance in strains that are otherwise susceptible to antibiotic therapy. Previously, we identified a sulfonamide-containing scaffold molecule (ABEPI1) that reversed serum-associated antibiotic tolerance in A. baumannii. Herein, we present structure-activity relationship studies on 29 newly synthesized analogues. These molecules were characterized for their ability to potentiate multiple antibiotics in serum, reduce serum-associated ethidium bromide efflux and depolarize bacterial cell membranes. In addition, they were assessed for toxicity to mammalian cells. Collectively, these molecules may represent promising potential adjuvants for use in combination with new and existing antibiotics to treat A. baumannii bacterial infections.
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Affiliation(s)
- Michaelle Chojnacki
- Department of Microbiology and Immunology, University of Rochester Medical Center, 601 Elmwood Ave., Rochester, NY, 14642, USA
| | - Xufeng Cao
- Department of Medicinal Chemistry and Molecular Pharmacology College of Pharmacy, Purdue University, 575 Stadium Mall Dr., West Lafayette, IN, 47907
| | - Mikaeel Young
- Department of Microbiology and Immunology, University of Rochester Medical Center, 601 Elmwood Ave., Rochester, NY, 14642, USA
| | - Rebecca N Fritz
- Department of Medicinal Chemistry and Molecular Pharmacology College of Pharmacy, Purdue University, 575 Stadium Mall Dr., West Lafayette, IN, 47907
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester Medical Center, 601 Elmwood Ave., Rochester, NY, 14642, USA
| | - Daniel P Flaherty
- Department of Medicinal Chemistry and Molecular Pharmacology College of Pharmacy, Purdue University, 575 Stadium Mall Dr., West Lafayette, IN, 47907.,Purdue Institute for Drug Discovery, 720 Clinic Dr., West Lafayette, IN, 47907, USA.,Purdue Institute of Inflammation, Immunology and Infectious Disease, 207 South Martin Jischke Dr., West Lafayette, IN, 47907, USA
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12
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Morrison JM, Chojnacki M, Fadrowski JJ, Bauza C, Dunman PM, Dudas RA, Goldenberg NA, Berman DM. Serum-Associated Antibiotic Tolerance in Pediatric Clinical Isolates of Pseudomonas aeruginosa. J Pediatric Infect Dis Soc 2019; 9:671-679. [PMID: 31886511 PMCID: PMC7974018 DOI: 10.1093/jpids/piz094] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 12/05/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND When grown in human serum, laboratory isolates of Pseudomonas aeruginosa exhibit tolerance to antibiotics at inhibitory concentrations. This phenomenon, known as serum-associated antibiotic tolerance (SAT), could lead to clinical treatment failure of pseudomonal infections. Our purpose in this study was to determine the prevalence and clinical impact of SAT in Pseudomonas isolates in hospitalized children. METHODS The SAT phenotype was assessed in patients aged <18 years admitted with respiratory or blood cultures positive for P. aeruginosa. The SAT phenotype was a priori defined as a ≥2-log increase in colony-forming units when grown in human serum compared with Luria-Bertani medium in the presence of minocycline or tobramycin. RESULTS SAT was detected in 29 (64%) patients. Fourteen patients each (34%) had cystic fibrosis (CF) and tracheostomies. Patient demographics and comorbidities did not differ by SAT status. Among CF patients, SAT was associated with longer duration of intravenous antibiotics (10 days vs 5 days; P < .01). CONCLUSIONS This study establishes that SAT exists in P. aeruginosa from human serum and may be a novel factor that contributes to differences in clinical outcomes. Future research should investigate the mechanisms that contribute to SAT in order to identify novel targets for adjunctive antimicrobial therapies.
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Affiliation(s)
- John M Morrison
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA,Department of Medicine, Division of Hospital Medicine, Johns Hopkins All Children’s Hospital, St. Petersburg, Florida, USA,Correspondence: John M. Morrison, 601 Fifth Street South Suite 501, Saint Petersburg, FL 33701 ()
| | - Michaelle Chojnacki
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, USA
| | - Jeffrey J Fadrowski
- Department of Pediatrics, Division of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Colleen Bauza
- Department of Health Informatics, Johns Hopkins All Children’s Hospital, St. Petersburg, Florida, USA
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, USA
| | - Robert A Dudas
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA,Department of Medicine, Division of Hospital Medicine, Johns Hopkins All Children’s Hospital, St. Petersburg, Florida, USA
| | - Neil A Goldenberg
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA, and All Children’s Research Institute, Johns Hopkins All Children’s Hospital, St. Petersburg, Florida, USA
| | - David M Berman
- Department of Medicine, Division of Infectious Diseases, Johns Hopkins All Children’s Hospital, St. Petersburg, Florida, USA
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13
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Shehatou C, Logunov SL, Dunman PM, Haidaris CG, Klubben WS. Characterizing the Antimicrobial Properties of 405 nm Light and the Corning® Light-Diffusing Fiber Delivery System. Lasers Surg Med 2019; 51:887-896. [PMID: 31302937 PMCID: PMC6916415 DOI: 10.1002/lsm.23132] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2019] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND OBJECTIVES Hospital-acquired infections (HAIs) and multidrug resistant bacteria pose a significant threat to the U.S. healthcare system. With a dearth of new antibiotic approvals, novel antimicrobial strategies are required to help solve this problem. Violet-blue visible light (400-470 nm) has been shown to elicit strong antimicrobial effects toward many pathogens, including representatives of the ESKAPE bacterial pathogens, which have a high propensity to cause HAIs. However, phototherapeutic solutions to prevention or treating infections are currently limited by efficient and nonobtrusive light-delivery mechanisms. STUDY DESIGN/MATERIALS AND METHODS Here, we investigate the in vitro antimicrobial properties of flexible Corning® light-diffusing fiber (LDF) toward members of the ESKAPE pathogens in a variety of growth states and in the context of biological materials. Bacteria were grown on agar surfaces, in liquid culture and on abiotic surfaces. We also explored the effects of 405 nm light within the presence of lung surfactant, human serum, and on eukaryotic cells. Pathogens tested include Enterococcus spp, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., Staphylococcus epidermidis, Streptococcus pyogenes, Candida albicans, and Escherichia coli. RESULTS Overall, the LDF delivery of 405 nm violet-blue light exerted a significant degree of microbicidal activity against a wide range of pathogens under diverse experimental conditions. CONCLUSIONS The results exemplify the fiber's promise as a non-traditional approach for the prevention and/or therapeutic intervention of HAIs. Lasers Surg. Med. © 2019 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Cindy Shehatou
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York, 14642
| | - Stephan L Logunov
- Division of Science and Technology, Corning Research & Development Corporation, Corning, New York, 14831
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York, 14642
| | - Constantine G Haidaris
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York, 14642
| | - W Spencer Klubben
- Division of Science and Technology, Corning Research & Development Corporation, Corning, New York, 14831
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14
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Colquhoun JM, Ha L, Beckley A, Meyers B, Flaherty DP, Dunman PM. Identification of Small Molecule Inhibitors of Staphylococcus aureus RnpA. Antibiotics (Basel) 2019; 8:antibiotics8020048. [PMID: 31035380 PMCID: PMC6627331 DOI: 10.3390/antibiotics8020048] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 04/23/2019] [Accepted: 04/25/2019] [Indexed: 12/17/2022] Open
Abstract
Staphylococcus aureus RnpA is thought to be a unique dual functional antimicrobial target that is required for two essential cellular processes, precursor tRNA processing and messenger RNA degradation. Herein, we used a previously described whole cell-based mupirocin synergy assay to screen members of a 53,000 compound small molecule diversity library and simultaneously enrich for agents with cellular RnpA inhibitory activity. A medicinal chemistry-based campaign was launched to generate a preliminary structure activity relationship and guide early optimization of two novel chemical classes of RnpA inhibitors identified, phenylcarbamoyl cyclic thiophene and piperidinecarboxamide. Representatives of each chemical class displayed potent anti-staphylococcal activity, limited the protein’s in vitro ptRNA processing and mRNA degradation activities, and exhibited favorable therapeutic indexes. The most potent piperidinecarboxamide RnpA inhibitor, JC2, displayed inhibition of cellular RnpA mRNA turnover, RnpA-depletion strain hypersusceptibility, and exhibited antimicrobial efficacy in a wax worm model of S. aureus infection. Taken together, these results establish that the whole cell screening assay used is amenable to identifying small molecule RnpA inhibitors within large chemical libraries and that the chemical classes identified here may represent progenitors of new classes of antimicrobials that target RnpA.
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Affiliation(s)
- Jennifer M Colquhoun
- Department of Microbiology and Immunology, University of Rochester School of Medicine, Rochester, NY 14642, USA.
| | - Lisha Ha
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47906, USA.
| | - Andrew Beckley
- Department of Microbiology and Immunology, University of Rochester School of Medicine, Rochester, NY 14642, USA.
| | - Brinkley Meyers
- Department of Microbiology and Immunology, University of Rochester School of Medicine, Rochester, NY 14642, USA.
| | - Daniel P Flaherty
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47906, USA.
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN 47906, USA.
- Purdue Institute for Drug Discovery, Purdue University, West Lafayette, IN 47906, USA.
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester School of Medicine, Rochester, NY 14642, USA.
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15
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Trombetta RP, Ninomiya MJ, El-Atawneh IM, Knapp EK, de Mesy Bentley KL, Dunman PM, Schwarz EM, Kates SL, Awad HA. Calcium Phosphate Spacers for the Local Delivery of Sitafloxacin and Rifampin to Treat Orthopedic Infections: Efficacy and Proof of Concept in a Mouse Model of Single-Stage Revision of Device-Associated Osteomyelitis. Pharmaceutics 2019; 11:E94. [PMID: 30813284 PMCID: PMC6410209 DOI: 10.3390/pharmaceutics11020094] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/12/2019] [Accepted: 02/17/2019] [Indexed: 12/15/2022] Open
Abstract
Osteomyelitis is a chronic bone infection that is often treated with adjuvant antibiotic-impregnated poly(methyl methacrylate) (PMMA) cement spacers in multi-staged revisions. However, failure rates remain substantial due to recurrence of infection, which is attributed to the poor performance of the PMMA cement as a drug release device. Hence, the objective of this study was to design and evaluate a bioresorbable calcium phosphate scaffold (CaPS) for sustained antimicrobial drug release and investigate its efficacy in a murine model of femoral implant-associated osteomyelitis. Incorporating rifampin and sitafloxacin, which are effective against bacterial phenotypes responsible for bacterial persistence, into 3D-printed CaPS coated with poly(lactic co-glycolic) acid, achieved controlled release for up to two weeks. Implantation into the murine infection model resulted in decreased bacterial colonization rates at 3- and 10-weeks post-revision for the 3D printed CaPS in comparison to gentamicin-laden PMMA. Furthermore, a significant increase in bone formation was observed for 3D printed CaPS incorporated with rifampin at 3 and 10 weeks. The results of this study demonstrate that osteoconductive 3D printed CaPS incorporated with antimicrobials demonstrate more efficacious bacterial colonization outcomes and bone growth in a single-stage revision in comparison to gentamicin-laden PMMA requiring a two-stage revision.
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Affiliation(s)
- Ryan P Trombetta
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA.
- Center for Musculoskeletal Research, University of Rochester, Rochester, NY 14642, USA.
| | - Mark J Ninomiya
- Center for Musculoskeletal Research, University of Rochester, Rochester, NY 14642, USA.
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY 14642, USA.
| | - Ihab M El-Atawneh
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA.
- Center for Musculoskeletal Research, University of Rochester, Rochester, NY 14642, USA.
| | - Emma K Knapp
- Center for Musculoskeletal Research, University of Rochester, Rochester, NY 14642, USA.
- Department of Orthopedics, University of Rochester Medical Center, Rochester, NY 14642, USA.
| | - Karen L de Mesy Bentley
- Center for Musculoskeletal Research, University of Rochester, Rochester, NY 14642, USA.
- Department of Pathology & Laboratory Medicine, University of Rochester, Rochester, NY 14642, USA.
- Department of Orthopedics, University of Rochester Medical Center, Rochester, NY 14642, USA.
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY 14642, USA.
| | - Edward M Schwarz
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA.
- Center for Musculoskeletal Research, University of Rochester, Rochester, NY 14642, USA.
- Department of Pathology & Laboratory Medicine, University of Rochester, Rochester, NY 14642, USA.
- Department of Orthopedics, University of Rochester Medical Center, Rochester, NY 14642, USA.
| | - Stephen L Kates
- Center for Musculoskeletal Research, University of Rochester, Rochester, NY 14642, USA.
- Department of Orthopaedic Surgery, Virginia Commonwealth University School of Medicine, Richmond, VA 0153, USA.
| | - Hani A Awad
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA.
- Center for Musculoskeletal Research, University of Rochester, Rochester, NY 14642, USA.
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16
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Ha L, Colquhoun J, Noinaj N, Das C, Dunman PM, Flaherty DP. Crystal structure of the ribonuclease-P-protein subunit from Staphylococcus aureus. Acta Crystallogr F Struct Biol Commun 2018; 74:632-637. [PMID: 30279314 PMCID: PMC6168776 DOI: 10.1107/s2053230x18011512] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/14/2018] [Indexed: 02/03/2023] Open
Abstract
Staphylococcus aureus ribonuclease-P-protein subunit (RnpA) is a promising antimicrobial target that is a key protein component for two essential cellular processes, RNA degradation and transfer-RNA (tRNA) maturation. The first crystal structure of RnpA from the pathogenic bacterial species, S. aureus, is reported at 2.0 Å resolution. The structure presented maintains key similarities with previously reported RnpA structures from bacteria and archaea, including the highly conserved RNR-box region and aromatic residues in the precursor-tRNA 5'-leader-binding domain. This structure will be instrumental in the pursuit of structure-based designed inhibitors targeting RnpA-mediated RNA processing as a novel therapeutic approach for treating S. aureus infections.
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MESH Headings
- Amino Acid Sequence
- Bacterial Proteins/chemistry
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Catalytic Domain
- Cloning, Molecular
- Crystallography, X-Ray
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Gene Expression
- Genetic Vectors/chemistry
- Genetic Vectors/metabolism
- Kinetics
- Models, Molecular
- Protein Binding
- Protein Conformation, alpha-Helical
- Protein Conformation, beta-Strand
- Protein Interaction Domains and Motifs
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Transfer/chemistry
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Ribonuclease P/chemistry
- Ribonuclease P/genetics
- Ribonuclease P/metabolism
- Sequence Alignment
- Sequence Homology, Amino Acid
- Staphylococcus aureus/chemistry
- Staphylococcus aureus/enzymology
- Substrate Specificity
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Affiliation(s)
- Lisha Ha
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA
| | - Jennifer Colquhoun
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Nicholas Noinaj
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN 47907, USA
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN 47907, USA
| | - Chittaranjan Das
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN 47907, USA
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Paul M. Dunman
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Daniel P. Flaherty
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN 47907, USA
- Purdue Institute for Drug Discovery, Purdue University, West Lafayette, IN 47907, USA
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17
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Liang H, Zhou G, Ge Y, D'Ambrosio EA, Eidem TM, Blanchard C, Shehatou C, Chatare VK, Dunman PM, Valentine AM, Voelz VA, Grimes CL, Andrade RB. Elucidating the inhibition of peptidoglycan biosynthesis in Staphylococcus aureus by albocycline, a macrolactone isolated from Streptomyces maizeus. Bioorg Med Chem 2018; 26:3453-3460. [PMID: 29805074 PMCID: PMC6008248 DOI: 10.1016/j.bmc.2018.05.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 05/02/2018] [Accepted: 05/12/2018] [Indexed: 02/01/2023]
Abstract
Antibiotic resistance is a serious threat to global public health, and methicillin-resistant Staphylococcus aureus (MRSA) is a poignant example. The macrolactone natural product albocycline, derived from various Streptomyces strains, was recently identified as a promising antibiotic candidate for the treatment of both MRSA and vancomycin-resistant S. aureus (VRSA), which is another clinically relevant and antibiotic resistant strain. Moreover, it was hypothesized that albocycline's antimicrobial activity was derived from the inhibition of peptidoglycan (i.e., bacterial cell wall) biosynthesis. Herein, preliminary mechanistic studies are performed to test the hypothesis that albocycline inhibits MurA, the enzyme that catalyzes the first step of peptidoglycan biosynthesis, using a combination of biological assays alongside molecular modeling and simulation studies. Computational modeling suggests albocycline exists as two conformations in solution, and computational docking of these conformations to an ensemble of simulated receptor structures correctly predicted preferential binding to S. aureus MurA-the enzyme that catalyzes the first step of peptidoglycan biosynthesis-over Escherichia coli (E. coli) MurA. Albocycline isolated from the producing organism (Streptomyces maizeus) weakly inhibited S. aureus MurA (IC50 of 480 μM) but did not inhibit E. coli MurA. The antimicrobial activity of albocycline against resistant S. aureus strains was superior to that of vancomycin, preferentially inhibiting Gram-positive organisms. Albocycline was not toxic to human HepG2 cells in MTT assays. While these studies demonstrate that albocycline is a promising lead candidate against resistant S. aureus, taken together they suggest that MurA is not the primary target, and further work is necessary to identify the major biological target.
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Affiliation(s)
- Hai Liang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States
| | - Guangfeng Zhou
- Department of Chemistry, Temple University, Philadelphia, PA 19122, United States
| | - Yunhui Ge
- Department of Chemistry, Temple University, Philadelphia, PA 19122, United States
| | - Elizabeth A D'Ambrosio
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States
| | - Tess M Eidem
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, United States
| | - Catlyn Blanchard
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, United States
| | - Cindy Shehatou
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, United States
| | - Vijay K Chatare
- Department of Chemistry, Temple University, Philadelphia, PA 19122, United States
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, United States
| | - Ann M Valentine
- Department of Chemistry, Temple University, Philadelphia, PA 19122, United States
| | - Vincent A Voelz
- Department of Chemistry, Temple University, Philadelphia, PA 19122, United States
| | - Catherine L Grimes
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States
| | - Rodrigo B Andrade
- Department of Chemistry, Temple University, Philadelphia, PA 19122, United States.
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18
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Choby JE, Mike LA, Mashruwala AA, Dutter BF, Dunman PM, Sulikowski GA, Boyd JM, Skaar EP. A Small-Molecule Inhibitor of Iron-Sulfur Cluster Assembly Uncovers a Link between Virulence Regulation and Metabolism in Staphylococcus aureus. Cell Chem Biol 2016; 23:1351-1361. [PMID: 27773628 DOI: 10.1016/j.chembiol.2016.09.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 09/01/2016] [Accepted: 09/30/2016] [Indexed: 11/28/2022]
Abstract
The rising problem of antimicrobial resistance in Staphylococcus aureus necessitates the discovery of novel therapeutic targets for small-molecule intervention. A major obstacle of drug discovery is identifying the target of molecules selected from high-throughput phenotypic assays. Here, we show that the toxicity of a small molecule termed '882 is dependent on the constitutive activity of the S. aureus virulence regulator SaeRS, uncovering a link between virulence factor production and energy generation. A series of genetic, physiological, and biochemical analyses reveal that '882 inhibits iron-sulfur (Fe-S) cluster assembly most likely through inhibition of the Suf complex, which synthesizes Fe-S clusters. In support of this, '882 supplementation results in decreased activity of the Fe-S cluster-dependent enzyme aconitase. Further information regarding the effects of '882 has deepened our understanding of virulence regulation and demonstrates the potential for small-molecule modulation of Fe-S cluster assembly in S. aureus and other pathogens.
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Affiliation(s)
- Jacob E Choby
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Graduate Program in Microbiology & Immunology, Vanderbilt University, Nashville, TN 37232, USA
| | - Laura A Mike
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Ameya A Mashruwala
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901, USA
| | - Brendan F Dutter
- Department of Chemistry, Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Gary A Sulikowski
- Department of Chemistry, Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Jeffrey M Boyd
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901, USA.
| | - Eric P Skaar
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Veterans Affairs Tennessee Valley Healthcare Services, Nashville, TN 37232, USA.
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19
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Wilde AD, Snyder DJ, Putnam NE, Valentino MD, Hammer ND, Lonergan ZR, Hinger SA, Aysanoa EE, Blanchard C, Dunman PM, Wasserman GA, Chen J, Shopsin B, Gilmore MS, Skaar EP, Cassat JE. Bacterial Hypoxic Responses Revealed as Critical Determinants of the Host-Pathogen Outcome by TnSeq Analysis of Staphylococcus aureus Invasive Infection. PLoS Pathog 2015; 11:e1005341. [PMID: 26684646 PMCID: PMC4684308 DOI: 10.1371/journal.ppat.1005341] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 11/23/2015] [Indexed: 12/11/2022] Open
Abstract
Staphylococcus aureus is capable of infecting nearly every organ in the human body. In order to infiltrate and thrive in such diverse host tissues, staphylococci must possess remarkable flexibility in both metabolic and virulence programs. To investigate the genetic requirements for bacterial survival during invasive infection, we performed a transposon sequencing (TnSeq) analysis of S. aureus during experimental osteomyelitis. TnSeq identified 65 genes essential for staphylococcal survival in infected bone and an additional 148 mutants with compromised fitness in vivo. Among the loci essential for in vivo survival was SrrAB, a staphylococcal two-component system previously reported to coordinate hypoxic and nitrosative stress responses in vitro. Healthy bone is intrinsically hypoxic, and intravital oxygen monitoring revealed further decreases in skeletal oxygen concentrations upon S. aureus infection. The fitness of an srrAB mutant during osteomyelitis was significantly increased by depletion of neutrophils, suggesting that neutrophils impose hypoxic and/or nitrosative stresses on invading bacteria. To more globally evaluate staphylococcal responses to changing oxygenation, we examined quorum sensing and virulence factor production in staphylococci grown under aerobic or hypoxic conditions. Hypoxic growth resulted in a profound increase in quorum sensing-dependent toxin production, and a concomitant increase in cytotoxicity toward mammalian cells. Moreover, aerobic growth limited quorum sensing and cytotoxicity in an SrrAB-dependent manner, suggesting a mechanism by which S. aureus modulates quorum sensing and toxin production in response to environmental oxygenation. Collectively, our results demonstrate that bacterial hypoxic responses are key determinants of the staphylococcal-host interaction.
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Affiliation(s)
- Aimee D. Wilde
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Daniel J. Snyder
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Nicole E. Putnam
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Michael D. Valentino
- Departments of Ophthalmology and Microbiology and Immunology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Neal D. Hammer
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Zachery R. Lonergan
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Scott A. Hinger
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Esar E. Aysanoa
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Catlyn Blanchard
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Paul M. Dunman
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Gregory A. Wasserman
- Departments of Medicine and Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - John Chen
- Skirball Institute Program in Molecular Pathogenesis, Departments of Microbiology and Medicine, New York University Medical Center, New York, New York, United States of America
| | - Bo Shopsin
- Departments of Medicine and Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Michael S. Gilmore
- Departments of Ophthalmology and Microbiology and Immunology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Veterans Affairs Tennessee Valley Healthcare Services, Nashville, Tennessee, United States of America
| | - James E. Cassat
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * E-mail:
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20
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Colquhoun JM, Wozniak RAF, Dunman PM. Clinically Relevant Growth Conditions Alter Acinetobacter baumannii Antibiotic Susceptibility and Promote Identification of Novel Antibacterial Agents. PLoS One 2015; 10:e0143033. [PMID: 26558753 PMCID: PMC4641712 DOI: 10.1371/journal.pone.0143033] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 10/29/2015] [Indexed: 12/13/2022] Open
Abstract
Biological processes that govern bacterial proliferation and survival in the host-environment(s) are likely to be vastly different from those that are required for viability in nutrient-rich laboratory media. Consequently, growth-based antimicrobial screens performed in conditions modeling aspects of bacterial disease states have the potential to identify new classes of antimicrobials that would be missed by screens performed in conventional laboratory media. Accordingly, we performed screens of the Selleck library of 853 FDA approved drugs for agents that exhibit antimicrobial activity toward the Gram-negative bacterial pathogen Acinetobacter baumannii during growth in human serum, lung surfactant, and/or the organism in the biofilm state and compared those results to that of conventional laboratory medium. Results revealed that a total of 90 compounds representing 73 antibiotics and 17 agents that were developed for alternative therapeutic indications displayed antimicrobial properties toward the test strain in at least one screening condition. Of the active library antibiotics only four agents, rifampin, rifaximin, ciprofloxacin and tetracycline, exhibited antimicrobial activity toward the organism during all screening conditions, whereas the remainder were inactive in ≥ 1 condition; 56 antibiotics were inactive during serum growth, 25 and 38 were inactive toward lung surfactant grown and biofilm-associated cells, respectively, suggesting that subsets of antibiotics may outperform others in differing infection settings. Moreover, 9 antibiotics that are predominantly used for the treatment Gram-positive pathogens and 10 non-antibiotics lacked detectable antimicrobial activity toward A. baumannii grown in conventional medium but were active during ≥ 1 alternative growth condition(s). Such agents may represent promising anti-Acinetobacter agents that would have likely been overlooked by antimicrobial whole cell screening assays performed in traditional laboratory screening media.
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Affiliation(s)
- Jennifer M. Colquhoun
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Rachel A. F. Wozniak
- Department of Ophthalmology, Flaum Eye Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Paul M. Dunman
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
- * E-mail:
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21
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Dunman PM, Tomaras AP. Editorial overview: Antimicrobials. Curr Opin Microbiol 2015; 27:v-vii. [PMID: 26384621 DOI: 10.1016/j.mib.2015.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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22
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Dunman PM, Tomaras AP. Translational deficiencies in antibacterial discovery and new screening paradigms. Curr Opin Microbiol 2015; 27:108-13. [PMID: 26356258 DOI: 10.1016/j.mib.2015.08.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 08/23/2015] [Accepted: 08/24/2015] [Indexed: 10/23/2022]
Abstract
An impending disaster is currently developing in the infectious disease community: the combination of rapidly emerging multidrug-resistance among clinically relevant bacterial pathogens, together with an unprecedented withdrawal from industrial dedication to this disease area, is jeopardizing human health on a societal level. For those who remain focused and dedicated to identifying solutions to this growing problem, additional challenges await when in vitro activity does not correlate with in vivo efficacy. Thus the development of more effective translational assays will greatly improve and streamline the process of identifying novel antibacterial agents that can stand the test of preclinical and clinical development. Here we describe recent examples of research that justify the need for such assays.
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Affiliation(s)
- Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, United States.
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23
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Tomaras AP, Dunman PM. In the midst of the antimicrobial discovery conundrum: an overview. Curr Opin Microbiol 2015; 27:103-7. [PMID: 26356257 DOI: 10.1016/j.mib.2015.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 08/23/2015] [Accepted: 08/26/2015] [Indexed: 11/19/2022]
Affiliation(s)
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester, School of Medicine and Dentistry, Rochester, NY 14642, United States.
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24
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Sheehan LM, Budnick JA, Blanchard C, Dunman PM, Caswell CC. A LysR-family transcriptional regulator required for virulence in Brucella abortus is highly conserved among the α-proteobacteria. Mol Microbiol 2015; 98:318-28. [PMID: 26175079 DOI: 10.1111/mmi.13123] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2015] [Indexed: 12/31/2022]
Abstract
Small RNAs are principal elements of bacterial gene regulation and physiology. Two small RNAs in Brucella abortus, AbcR1 and AbcR2, are required for wild-type virulence. Examination of the abcR loci revealed the presence of a gene encoding a LysR-type transcriptional regulator flanking abcR2 on chromosome 1. Deletion of this lysR gene (bab1_1517) resulted in the complete loss of abcR2 expression while no difference in abcR1 expression was observed. The B. abortus bab1_1517 mutant strain was significantly attenuated in macrophages and mice, and bab1_1517 was subsequently named vtlR for virulence-associated transcriptional LysR-family regulator. Microarray analysis revealed three additional genes encoding small hypothetical proteins also under the control of VtlR. Electrophoretic mobility shift assays demonstrated that VtlR binds directly to the promoter regions of abcR2 and the three hypothetical protein-encoding genes, and DNase I footprint analysis identified the specific nucleotide sequence in these promoters that VtlR binds to and drives gene expression. Strikingly, orthologs of VtlR are encoded in a wide range of host-associated α-proteobacteria, and it is likely that the VtlR genetic system represents a common regulatory circuit critical for host-bacterium interactions.
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Affiliation(s)
- Lauren M Sheehan
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24060, USA
| | - James A Budnick
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Catlyn Blanchard
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Clayton C Caswell
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24060, USA
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25
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Forbes L, Ebsworth-Mojica K, DiDone L, Li SG, Freundlich JS, Connell N, Dunman PM, Krysan DJ. A High Throughput Screening Assay for Anti-Mycobacterial Small Molecules Based on Adenylate Kinase Release as a Reporter of Cell Lysis. PLoS One 2015; 10:e0129234. [PMID: 26098625 PMCID: PMC4476654 DOI: 10.1371/journal.pone.0129234] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 05/06/2015] [Indexed: 02/02/2023] Open
Abstract
Mycobacterium tuberculosis (Mtb) is well-established to be one of the most important bacterial pathogens for which new antimicrobial therapies are needed. Herein, we describe the development of a high throughput screening assay for the identification of molecules that are bactericidal against Mycobacteria. The assay utilizes the release of the intracellular enzyme adenylate kinase into the culture medium as a reporter of mycobacterial cell death. We demonstrate that the assay is selective for mycobactericidal molecules and detects anti-mycobacterial activity at concentrations below the minimum inhibitory concentration of many molecules. Thus, the AK assay is more sensitive than traditional growth assays. We have validated the AK assay in the HTS setting using the Mtb surrogate organism M. smegmatis and libraries of FDA approved drugs as well as a commercially available Diversity set. The screen of the FDA-approved library demonstrated that the AK assay is able to identify the vast majority of drugs with known mycobactericidal activity. Importantly, our screen of the Diversity set revealed that the increased sensitivity of the AK assay increases the ability of M. smegmatis-based screens to detect molecules with relatively poor activity against M. smegmatis but good to excellent activity against Mtb.
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Affiliation(s)
- Lauren Forbes
- Department of Microbiology/Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York, 14642, United States of America
| | - Katherine Ebsworth-Mojica
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, New York, 14642, United States of America
| | - Louis DiDone
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, New York, 14642, United States of America
| | - Shao-Gang Li
- Department of Pharmacology, Rutgers University, Newark, New Jersey, 07103, United States of America
| | - Joel S. Freundlich
- Department of Pharmacology, Rutgers University, Newark, New Jersey, 07103, United States of America
- Department of Physiology, Rutgers University, Newark, New Jersey, 07103, United States of America
- Department of Medicine, Center for Emerging and Re-emerging Pathogens, Rutgers University, Newark, New Jersey, 07103, United States of America
| | - Nancy Connell
- Department of Physiology, Rutgers University, Newark, New Jersey, 07103, United States of America
- Department of Medicine, Center for Emerging and Re-emerging Pathogens, Rutgers University, Newark, New Jersey, 07103, United States of America
| | - Paul M. Dunman
- Department of Microbiology/Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York, 14642, United States of America
- * E-mail: (DJK); (PMD)
| | - Damian J. Krysan
- Department of Microbiology/Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York, 14642, United States of America
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, New York, 14642, United States of America
- * E-mail: (DJK); (PMD)
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26
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Mootz JM, Benson MA, Heim CE, Crosby HA, Kavanaugh JS, Dunman PM, Kielian T, Torres VJ, Horswill AR. Rot is a key regulator of Staphylococcus aureus biofilm formation. Mol Microbiol 2015; 96:388-404. [PMID: 25612137 DOI: 10.1111/mmi.12943] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2015] [Indexed: 01/28/2023]
Abstract
Staphylococcus aureus is a significant cause of chronic biofilm infections on medical implants. We investigated the biofilm regulatory cascade and discovered that the repressor of toxins (Rot) is part of this pathway. A USA300 community-associated methicillin-resistant S. aureus strain deficient in Rot was unable to form a biofilm using multiple different assays, and we found rot mutants in other strain lineages were also biofilm deficient. By performing a global analysis of transcripts and protein production controlled by Rot, we observed that all the secreted protease genes were up-regulated in a rot mutant, and we hypothesized that this regulation could be responsible for the biofilm phenotype. To investigate this question, we determined that Rot bound to the protease promoters, and we observed that activity levels of these enzymes, in particular the cysteine proteases, were increased in a rot mutant. By inactivating these proteases, biofilm capacity was restored to the mutant, demonstrating they are responsible for the biofilm negative phenotype. Finally, we tested the rot mutant in a mouse catheter model of biofilm infection and observed a significant reduction in biofilm burden. Thus S. aureus uses the transcription factor Rot to repress secreted protease levels in order to build a biofilm.
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Affiliation(s)
- Joe M Mootz
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
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27
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Hanses F, Roux C, Dunman PM, Salzberger B, Lee JC. Staphylococcus aureus gene expression in a rat model of infective endocarditis. Genome Med 2014; 6:93. [PMID: 25392717 PMCID: PMC4228149 DOI: 10.1186/s13073-014-0093-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/20/2014] [Indexed: 01/04/2023] Open
Abstract
Background Diabetes mellitus is a frequent underlying comorbidity in patients with Staphylococcus aureus endocarditis, and it represents a risk factor for complications and a negative outcome. The pathogenesis of staphylococcal endocardial infections in diabetic hosts has been poorly characterized, and little is known about S. aureus gene expression in endocardial vegetations. Methods We utilized a rat model of experimental S. aureus endocarditis to compare the pathogenesis of staphylococcal infection in diabetic and nondiabetic hosts and to study the global S. aureus transcriptome in endocardial vegetations in vivo. Results Diabetic rats had higher levels of bacteremia and larger endocardial vegetations than nondiabetic control animals. Microarray analyses revealed that 61 S. aureus genes were upregulated in diabetic rats, and the majority of these bacterial genes were involved in amino acid and carbohydrate metabolism. When bacterial gene expression in vivo (diabetic or nondiabetic endocardial vegetations) was compared to in vitro growth conditions, higher in vivo expression of genes encoding toxins and proteases was observed. Additionally, genes involved in the production of adhesins, capsular polysaccharide, and siderophores, as well as in amino acid and carbohydrate transport and metabolism, were upregulated in endocardial vegetations. To test the contribution of selected upregulated genes to the pathogenesis of staphylococcal endocarditis, isogenic deletion mutants were utilized. A mutant defective in production of the siderophore staphyloferrin B was attenuated in the endocarditis model, whereas the virulence of a surface adhesin (ΔsdrCDE) mutant was similar to that of the parental S. aureus strain. Conclusions Our results emphasize the relevance of diabetes mellitus as a risk factor for infectious endocarditis and provide a basis for understanding gene expression during staphylococcal infections in vivo. Electronic supplementary material The online version of this article (doi:10.1186/s13073-014-0093-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Frank Hanses
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115 USA ; Department of Internal Medicine I, University Hospital Regensburg, Franz-Josef-Strauss Allee 11, Regensburg, 93049 Germany
| | - Christelle Roux
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY 14642 USA
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY 14642 USA
| | - Bernd Salzberger
- Department of Internal Medicine I, University Hospital Regensburg, Franz-Josef-Strauss Allee 11, Regensburg, 93049 Germany
| | - Jean C Lee
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115 USA
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28
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Perlmutter J, Forbes LT, Krysan DJ, Ebsworth-Mojica K, Colquhoun JM, Wang J, Dunman PM, Flaherty DP. Repurposing the antihistamine terfenadine for antimicrobial activity against Staphylococcus aureus. J Med Chem 2014; 57:8540-62. [PMID: 25238555 PMCID: PMC4207543 DOI: 10.1021/jm5010682] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Indexed: 01/28/2023]
Abstract
Staphylococcus aureus is a rapidly growing health threat in the U.S., with resistance to several commonly prescribed treatments. A high-throughput screen identified the antihistamine terfenadine to possess, previously unreported, antimicrobial activity against S. aureus and other Gram-positive bacteria. In an effort to repurpose this drug, structure-activity relationship studies yielded 84 terfenadine-based analogues with several modifications providing increased activity versus S. aureus and other bacterial pathogens, including Mycobacterium tuberculosis. Mechanism of action studies revealed these compounds to exert their antibacterial effects, at least in part, through inhibition of the bacterial type II topoisomerases. This scaffold suffers from hERG liabilities which were not remedied through this round of optimization; however, given the overall improvement in activity of the set, terfenadine-based analogues provide a novel structural class of antimicrobial compounds with potential for further characterization as part of the continuing process to meet the current need for new antibiotics.
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Affiliation(s)
- Jessamyn
I. Perlmutter
- Department
of Microbiology and Immunology, University
of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United
States
| | - Lauren T. Forbes
- Department
of Microbiology and Immunology, University
of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United
States
| | - Damian J. Krysan
- Department
of Pediatrics, University of Rochester Medical
Center, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Katherine Ebsworth-Mojica
- Department
of Microbiology and Immunology, University
of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United
States
- Department
of Pediatrics, University of Rochester Medical
Center, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Jennifer M. Colquhoun
- Department
of Microbiology and Immunology, University
of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United
States
| | - Jenna
L. Wang
- Specialized
Chemistry Center, Delbert M. Shankel Structural Biology Center, University of Kansas, 2034 Becker Drive, Lawrence, Kansas 66047, United
States
| | - Paul M. Dunman
- Department
of Microbiology and Immunology, University
of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, United
States
| | - Daniel P. Flaherty
- Specialized
Chemistry Center, Delbert M. Shankel Structural Biology Center, University of Kansas, 2034 Becker Drive, Lawrence, Kansas 66047, United
States
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29
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Jacobs AC, Blanchard CE, Catherman SC, Dunman PM, Murata Y. An ribonuclease T2 family protein modulates Acinetobacter baumannii abiotic surface colonization. PLoS One 2014; 9:e85729. [PMID: 24489668 PMCID: PMC3904860 DOI: 10.1371/journal.pone.0085729] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 11/29/2013] [Indexed: 11/18/2022] Open
Abstract
Acinetobacter baumannii is an emerging bacterial pathogen of considerable medical concern. The organism's transmission and ability to cause disease has been associated with its propensity to colonize and form biofilms on abiotic surfaces in health care settings. To better understand the genetic determinants that affect biomaterial attachment, we performed a transposon mutagenesis analysis of abiotic surface-colonization using A. baumannii strain 98-37-09. Disruption of an RNase T2 family gene was found to limit the organism's ability to colonize polystyrene, polypropylene, glass, and stainless steel surfaces. DNA microarray analyses revealed that in comparison to wild type and complemented cells, the RNase T2 family mutant exhibited reduced expression of 29 genes, 15 of which are predicted to be associated with bacterial attachment and surface-associated motility. Motility assays confirmed that RNase T2 mutant displays a severe motility defect. Taken together, our results indicate that the RNase T2 family protein identified in this study is a positive regulator of A. baumannii's ability to colonize inanimate surfaces and motility. Moreover, the enzyme may be an effective target for the intervention of biomaterial colonization, and consequently limit the organism's transmission within the hospital setting.
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Affiliation(s)
- Anna C. Jacobs
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Catlyn E. Blanchard
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Seana C. Catherman
- Department of Medicine, Division of Infectious Diseases, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Paul M. Dunman
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
- * E-mail: (PMD); (YM)
| | - Yoshihiko Murata
- Department of Medicine, Division of Infectious Diseases, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
- * E-mail: (PMD); (YM)
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31
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Eidem TM, Coughlan A, Towler MR, Dunman PM, Wren AW. Drug-eluting cements for hard tissue repair: a comparative study using vancomycin and RNPA1000 to inhibit growth of Staphylococcus aureus. J Biomater Appl 2013; 28:1235-46. [PMID: 24029489 DOI: 10.1177/0885328213503388] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Bone cement used in orthopaedic applications can become colonized with bacterial biofilms, resulting in severe medical complications. Consequently, bone cements are often loaded with antibiotics in an effort to prevent bacterial colonization. However, current formulations may not release antibiotics into the environment at sufficient and sustained concentrations required to impede bacterial growth or may be incompatible with antibiotics that are effective against the colonizing organism. Thus, new cement formulation options are needed. This report describes the performance of a novel SiO2-TiO2-ZnO-CaO-SrO-based glass polyalkenoate cement as a carrier of antimicrobials active against Staphylococcus aureus, the predominant cause of orthopaedic biofilm-associated infections. The antibiotic vancomycin and a novel Staphylococcus aureus RnpA inhibitor under pre-clinical development, RNPA1000, were included in these studies. Rheological testing characterized the workability of the glass polyalkenoate cement over a range of powder-to-liquid ratios and polyacrylic acid concentrations and revealed that the most suitable powder-to-liquid ratio was 2/1.25 with 40 wt% polyacrylic acid. Loading glass polyalkenoate cement with either 20-30% RNPA1000 or vancomycin prevented bacterial growth. However, longer incubations allowed for Staphylococcus aureus colonies to form near the vancomycin-infused cement, indicating that vancomycin may not be suitable for long-term biofilm inhibition in comparison to RNPA1000. Scanning electron microscopy and energy-dispersive X-ray analyses confirmed successful incorporation RNPA1000 into the cement matrix and were indicative of its slow release. These studies establish a drug-eluting formulation of glass polyalkenoate cement with great potential in orthopaedic implants that incorporates known antibiotics as well as RNPA1000 to prevent growth of the dangerous pathogen Staphylococcus aureus.
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Affiliation(s)
- Tess M Eidem
- 1University of Rochester Medical Centre, Rochester, NY, USA
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Price-Whelan A, Poon CK, Benson MA, Eidem TT, Roux CM, Boyd JM, Dunman PM, Torres VJ, Krulwich TA. Transcriptional profiling of Staphylococcus aureus during growth in 2 M NaCl leads to clarification of physiological roles for Kdp and Ktr K+ uptake systems. mBio 2013; 4:e00407-13. [PMID: 23963175 PMCID: PMC3747578 DOI: 10.1128/mbio.00407-13] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 07/24/2013] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED Staphylococcus aureus exhibits an unusually high level of osmotolerance and Na(+) tolerance, properties that support survival in various host niches and in preserved foods. The genetic basis of these traits is not well understood. We compared the transcriptional profiles of S. aureus grown in complex medium with and without 2 M NaCl. The stimulon for growth in high-osmolality media and Na(+) included genes involved in uptake of K(+), other compatible solutes, sialic acid, and sugars; capsule biosynthesis; and amino acid and central metabolism. Quantitative PCR analysis revealed that the loci responded differently from each other to high osmolality imposed by elevated NaCl versus sucrose. High-affinity K(+) uptake (kdp) genes and capsule biosynthesis (cap5) genes required the two-component system KdpDE for full induction by osmotic stress, with kdpA induced more by NaCl and cap5B induced more by sucrose. Focusing on K(+) importers, we identified three S. aureus genes belonging to the lower-affinity Trk/Ktr family that encode two membrane proteins (KtrB and KtrD) and one accessory protein (KtrC). In the absence of osmotic stress, the ktr gene transcripts were much more abundant than the kdpA transcript. Disruption of S. aureus kdpA caused a growth defect under low-K(+) conditions, disruption of ktrC resulted in a significant defect in 2 M NaCl, and a ΔktrC ΔkdpA double mutant exhibited both phenotypes. Protective effects of S. aureus Ktr transporters at elevated NaCl are consistent with previous indications that both Na(+) and osmolality challenges are mitigated by the maintenance of a high cytoplasmic K(+) concentration. IMPORTANCE There is general agreement that the osmotolerance and Na(+) tolerance of Staphylococcus aureus are unusually high for a nonhalophile and support its capacity for human colonization, pathogenesis, and growth in food. Nonetheless, the molecular basis for these properties is not well defined. The genome-wide response of S. aureus to a high concentration, 2 M, of NaCl revealed the upregulation of expected genes, such as those for transporters of compatible solutes that are widely implicated in supporting osmotolerance. A high-affinity potassium uptake system, KdpFABC, was upregulated, although it generally plays a physiological role under very low K(+) conditions. At higher K(+) concentrations, a lower-affinity and more highly expressed type of K(+) transporter system, Ktr transporters, was shown to play a significant role in high Na(+) tolerance. This study illustrates the importance of the K(+) status of the cell for tolerance of Na(+) by S. aureus and underscores the importance of monovalent cation cycles in this pathogen.
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Affiliation(s)
- Alexa Price-Whelan
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Chun Kit Poon
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Meredith A. Benson
- Department of Microbiology, New York University School of Medicine, New York, New York, USA
| | - Tess T. Eidem
- Department of Microbiology and Immunology, University of Rochester, Rochester, New York, USA
| | - Christelle M. Roux
- Department of Microbiology and Immunology, University of Rochester, Rochester, New York, USA
| | - Jeffrey M. Boyd
- Department of Biochemistry and Microbiology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - Paul M. Dunman
- Department of Microbiology and Immunology, University of Rochester, Rochester, New York, USA
| | - Victor J. Torres
- Department of Microbiology, New York University School of Medicine, New York, New York, USA
| | - Terry A. Krulwich
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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Brinkman CL, Bumgarner R, Kittichotirat W, Dunman PM, Kuechenmeister LJ, Weaver KE. Characterization of the effects of an rpoC mutation that confers resistance to the Fst peptide toxin-antitoxin system toxin. J Bacteriol 2013; 195:156-66. [PMID: 23104812 PMCID: PMC3536179 DOI: 10.1128/jb.01597-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 10/22/2012] [Indexed: 01/24/2023] Open
Abstract
Overexpression of the Fst toxin in Enterococcus faecalis strain OG1X leads to defects in chromosome segregation, cell division and, eventually, membrane integrity. The M7 mutant derivative of OG1X is resistant to most of these effects but shows a slight growth defect in the absence of Fst. Full-genome sequencing revealed two differences between M7 and its OG1X parent. First, OG1X contains a frameshift mutation that inactivates the etaR response regulator gene, while M7 is a wild-type revertant for etaR. Second, the M7 mutant contains a missense mutation in the rpoC gene, which encodes the β' subunit of RNA polymerase. Mutagenesis experiments revealed that the rpoC mutation was primarily responsible for the resistance phenotype. Microarray analysis revealed that a number of transporters were induced in OG1X when Fst was overexpressed. These transporters were not induced in M7 in response to Fst, and further experiments indicated that this had a direct protective effect on the mutant cells. Therefore, exposure of cells to Fst appears to have a cascading effect, first causing membrane stress and then potentiation of these effects by overexpression of certain transporters.
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Affiliation(s)
- Cassandra L. Brinkman
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, South Dakota, USA
| | - Roger Bumgarner
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | | | - Paul M. Dunman
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Lisa J. Kuechenmeister
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Keith E. Weaver
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, South Dakota, USA
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Annadurai S, Martinez R, Canney DJ, Eidem T, Dunman PM, Abou-Gharbia M. Design and synthesis of 2-aminothiazole based antimicrobials targeting MRSA. Bioorg Med Chem Lett 2012; 22:7719-25. [PMID: 23116888 DOI: 10.1016/j.bmcl.2012.09.095] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 09/20/2012] [Accepted: 09/25/2012] [Indexed: 11/26/2022]
Abstract
Privileged structure-based libraries have been shown to provide high affinity lead compounds for a variety of important biological targets. The present study describes the synthesis and screening of a 2-aminothiazole based compound library to determine their utility as antimicrobials, focusing on MRSA. Several of the compounds in this series demonstrated improved antimicrobial activity as compared to ceftriaxone (CTX), a β-lactam antibiotic. The most potent compound (21) had MICs in the range of 2-4 μg/ml across a panel of Staphylococcus aureus strains. In addition, trifluoromethoxy substituted aminothiazoles and aminobenzothiazoles were found to be potent antimicrobials with MICs of 2-16 μg/ml.
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Affiliation(s)
- Sivakumar Annadurai
- Temple University School of Pharmacy, Moulder Center for Drug Discovery Research, Philadelphia, PA, USA
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35
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Caswell CC, Gaines JM, Ciborowski P, Smith D, Borchers CH, Roux CM, Sayood K, Dunman PM, Roop Ii RM. Identification of two small regulatory RNAs linked to virulence in Brucella abortus 2308. Mol Microbiol 2012; 85:345-60. [PMID: 22690807 DOI: 10.1111/j.1365-2958.2012.08117.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Hfq is an RNA-binding protein that functions in post-transcriptional gene regulation by mediating interactions between mRNAs and small regulatory RNAs (sRNAs). Two proteins encoded by BAB1_1794 and BAB2_0612 are highly over-produced in a Brucella abortus hfq mutant compared with the parental strain, and recently, expression of orthologues of these proteins in Agrobacterium tumefaciens was shown to be regulated by two sRNAs, called AbcR1 and AbcR2. Orthologous sRNAs (likewise designated AbcR1 and AbcR2) have been identified in B. abortus 2308. In Brucella, abcR1 and abcR2 single mutants are not defective in their ability to survive in cultured murine macrophages, but an abcR1 abcR2 double mutant exhibits significant attenuation in macrophages. Additionally, the abcR1 abcR2 double mutant displays significant attenuation in a mouse model of chronic Brucella infection. Quantitative proteomics and microarray analyses revealed that the AbcR sRNAs predominantly regulate genes predicted to be involved in amino acid and polyamine transport and metabolism, and Northern blot analyses indicate that the AbcR sRNAs accelerate the degradation of the target mRNAs. In an Escherichia coli two-plasmid reporter system, overexpression of either AbcR1 or AbcR2 was sufficient for regulation of target mRNAs, indicating that the AbcR sRNAs from B. abortus 2308 perform redundant regulatory functions.
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Affiliation(s)
- Clayton C Caswell
- Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville, NC 27834, USA
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Morrison JM, Anderson KL, Beenken KE, Smeltzer MS, Dunman PM. The staphylococcal accessory regulator, SarA, is an RNA-binding protein that modulates the mRNA turnover properties of late-exponential and stationary phase Staphylococcus aureus cells. Front Cell Infect Microbiol 2012; 2:26. [PMID: 22919618 PMCID: PMC3417590 DOI: 10.3389/fcimb.2012.00026] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 02/20/2012] [Indexed: 01/03/2023] Open
Abstract
The modulation of mRNA turnover is gaining recognition as a mechanism by which Staphylococcus aureus regulates gene expression, but the factors that orchestrate alterations in transcript degradation are poorly understood. In that regard, we previously found that 138 mRNA species, including transcripts coding for the virulence factors protein A (spa) and collagen-binding protein (cna), are stabilized in a sarA-dependent manner during exponential phase growth, suggesting that SarA directly or indirectly affects the RNA turnover properties of these transcripts. Herein, we expanded our characterization of the effects of sarA on mRNA turnover during late-exponential and stationary phases of growth. Results revealed that the locus affects the RNA degradation properties of cells during both growth phases. Further, using gel mobility shift assays and RIP-Chip, it was found that SarA protein is capable of binding mRNA species that it stabilizes both in vitro and within bacterial cells. Taken together, these results suggest that SarA post-transcriptionally regulates S. aureus gene expression in a manner that involves binding to and consequently altering the mRNA turnover properties of target transcripts.
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Affiliation(s)
- John M Morrison
- Department of Pathology and Microbiology, University of Nebraska Medical Center Omaha, NE, USA
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Abstract
The need for novel antibiotics is greater now than perhaps any time since the pre-antibiotic era. Indeed, the recent collapse of most pharmaceutical antibacterial groups, combined with the emergence of hypervirulent and pan-antibiotic-resistant bacteria have, in effect, created a 'perfect storm' that has severely compromised infection treatment options and led to dramatic increases in the incidence and severity of bacterial infections. To put simply, it is imperative that we develop new classes of antibiotics for the therapeutic intervention of bacterial infections. In that regard, RNA degradation is an essential biological process that has not been exploited for antibiotic development. Herein we discuss the factors that govern bacterial RNA degradation, highlight members of this machinery that represent attractive antimicrobial drug development targets and describe the use of high-throughput screening as a means of developing antimicrobials that target these enzymes. Such agents would represent first-in-class antibiotics that would be less apt to inactivation by currently encountered enzymatic antibiotic-resistance determinants.
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Affiliation(s)
- Tess M Eidem
- Department of Microbiology and Pathology, University of Nebraska Medical Center, Omaha, NE, USA
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Gardete S, Kim C, Hartmann BM, Mwangi M, Roux CM, Dunman PM, Chambers HF, Tomasz A. Genetic pathway in acquisition and loss of vancomycin resistance in a methicillin resistant Staphylococcus aureus (MRSA) strain of clonal type USA300. PLoS Pathog 2012; 8:e1002505. [PMID: 22319446 PMCID: PMC3271070 DOI: 10.1371/journal.ppat.1002505] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 12/12/2011] [Indexed: 12/01/2022] Open
Abstract
An isolate of the methicillin-resistant Staphylococcus aureus (MRSA) clone USA300 with reduced susceptibility to vancomycin (SG-R) (i.e, vancomycin-intermediate S. aureus, VISA) and its susceptible “parental” strain (SG-S) were recovered from a patient at the end and at the beginning of an unsuccessful vancomycin therapy. The VISA phenotype was unstable in vitro generating a susceptible revertant strain (SG-rev). The availability of these 3 isogenic strains allowed us to explore genetic correlates of antibiotic resistance as it emerged in vivo. Compared to the susceptible isolate, both the VISA and revertant strains carried the same point mutations in yycH, vraG, yvqF and lspA genes and a substantial deletion within an intergenic region. The revertant strain carried a single additional frameshift mutation in vraS which is part of two component regulatory system VraSR. VISA isolate SG-R showed complex alterations in phenotype: decreased susceptibility to other antibiotics, slow autolysis, abnormal cell division and increased thickness of cell wall. There was also altered expression of 239 genes including down-regulation of major virulence determinants. All phenotypic properties and gene expression profile returned to parental levels in the revertant strain. Introduction of wild type yvqF on a multicopy plasmid into the VISA strain caused loss of resistance along with loss of all the associated phenotypic changes. Introduction of the wild type vraSR into the revertant strain caused recovery of VISA type resistance. The yvqF/vraSR operon seems to function as an on/off switch: mutation in yvqF in strain SG-R turns on the vraSR system, which leads to increase in vancomycin resistance and down-regulation of virulence determinants. Mutation in vraS in the revertant strain turns off this regulatory system accompanied by loss of resistance and normal expression of virulence genes. Down-regulation of virulence genes may provide VISA strains with a “stealth” strategy to evade detection by the host immune system. The extensive use of antibiotics has led to the selection of methicillin-resistant S. aureus (MRSA) strains that are resistant to most antimicrobial agents and a treatment of choice against such strains is vancomycin. However, during the last decade reports of treatment failure with vancomycin non-susceptible MRSA (e.g., vancomycin intermediate S. aureus, VISA) began to appear in the clinical setting. In this paper we analyze the mechanism of resistance in a VISA strain that belongs to the epidemic and highly virulent MRSA clone USA300. We had 3 isogenic isolates available for analysis: the vancomycin susceptible parental strain recovered from the patient before the onset of therapy; the VISA strain recovered at the time of clinical treatment failure and a susceptible revertant of the VISA strain acquired during in vitro passage. We identified genetic differences among the three strains through whole genome sequencing. In this strain, the key genetic change responsible for vancomycin resistance was in the functionally connected yvqF/vraSR - two component sensory regulatory system involved with the control of cell wall metabolism of the bacteria. The same genetic change also caused repression of virulence related properties which may help the resistant bacteria to evade the host immune system.
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Affiliation(s)
- Susana Gardete
- Laboratory of Microbiology, The Rockefeller University, New York, New York, United States of America
- Molecular Genetics Laboratory, Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa, Oeiras, Portugal
| | - Choonkeun Kim
- Laboratory of Microbiology, The Rockefeller University, New York, New York, United States of America
| | - Boris M. Hartmann
- Department of Neurology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Michael Mwangi
- Laboratory of Microbiology, The Rockefeller University, New York, New York, United States of America
| | - Christelle M. Roux
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Paul M. Dunman
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Henry F. Chambers
- Division of Infectious Diseases, Department of Medicine, University of California San Francisco, San Francisco, California, United States of America
| | - Alexander Tomasz
- Laboratory of Microbiology, The Rockefeller University, New York, New York, United States of America
- * E-mail:
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Abstract
Staphylococcus aureus is a Gram-positive pathogen capable of causing a wide array of infections owing, in large part, to the coordinated expression of an extensive repertoire of virulence factors. Our laboratory and others have shown that the expression of these factors can occur post-transcriptionally at the level of mRNA turnover and is mediated by ribonucleases, RNA-binding proteins, and regulatory RNA molecules. Moreover, S. aureus harbors the ability to alter the stability of its mRNA titers in response to physiological stresses, including antibiotic exposure. Although ongoing studies are attempting to identify the molecular components that modulate S. aureus mRNA turnover, innovative approaches to target these essential processes have established a novel group of targets for therapeutic development against staphylococcal infections.
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Affiliation(s)
- John M Morrison
- Department of Pathology & Microbiology, University of Nebraska Medical Center, Omaha, NE 68198-5900, USA
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Jacobs AC, Sayood K, Olmsted SB, Blanchard CE, Hinrichs S, Russell D, Dunman PM. Characterization of the Acinetobacter baumannii growth phase-dependent and serum responsive transcriptomes. ACTA ACUST UNITED AC 2012; 64:403-12. [PMID: 22211672 DOI: 10.1111/j.1574-695x.2011.00926.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 11/23/2011] [Accepted: 12/20/2011] [Indexed: 11/29/2022]
Abstract
Acinetobacter baumannii has emerged as a bacterial pathogen of considerable healthcare concern. Yet, little is known about the organism's basic biological processes and the regulatory networks that modulate expression of its virulence factors and antibiotic resistance. Using Affymetrix GeneChips , we comprehensively defined and compared the transcriptomes of two A. baumannii strains, ATCC 17978 and 98-37-09, during exponential and stationary phase growth in Luria-Bertani (LB) medium. Results revealed that in addition to expected growth phase-associated metabolic changes, several putative virulence factors were dramatically regulated in a growth phase-dependent manner. Because a common feature between the two most severe types of A. baumannii infection, pneumonia and septicemia, includes the organism's dissemination to visceral organs via the circulatory system, microarray studies were expanded to define the expression properties of A. baumannii during growth in human serum. Growth in serum significantly upregulated iron acquisition systems, genes associated with epithelial cell adherence and DNA uptake, as well as numerous putative drug efflux pumps. Antibiotic susceptibility testing verified that the organism exhibits increased antibiotic tolerance when cultured in human serum, as compared to LB medium. Collectively, these studies provide researchers with a comprehensive database of A. baumannii's expression properties in LB medium and serum and identify biological processes that may contribute to the organism's virulence and antibiotic resistance.
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Affiliation(s)
- Anna C Jacobs
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA
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Olson PD, Kuechenmeister LJ, Anderson KL, Daily S, Beenken KE, Roux CM, Reniere ML, Lewis TL, Weiss WJ, Pulse M, Nguyen P, Simecka JW, Morrison JM, Sayood K, Asojo OA, Smeltzer MS, Skaar EP, Dunman PM. Small molecule inhibitors of Staphylococcus aureus RnpA alter cellular mRNA turnover, exhibit antimicrobial activity, and attenuate pathogenesis. PLoS Pathog 2011; 7:e1001287. [PMID: 21347352 PMCID: PMC3037362 DOI: 10.1371/journal.ppat.1001287] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Accepted: 01/10/2011] [Indexed: 11/23/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus is estimated to cause more U.S. deaths annually than HIV/AIDS. The emergence of hypervirulent and multidrug-resistant strains has further amplified public health concern and accentuated the need for new classes of antibiotics. RNA degradation is a required cellular process that could be exploited for novel antimicrobial drug development. However, such discovery efforts have been hindered because components of the Gram-positive RNA turnover machinery are incompletely defined. In the current study we found that the essential S. aureus protein, RnpA, catalyzes rRNA and mRNA digestion in vitro. Exploiting this activity, high through-put and secondary screening assays identified a small molecule inhibitor of RnpA-mediated in vitro RNA degradation. This agent was shown to limit cellular mRNA degradation and exhibited antimicrobial activity against predominant methicillin-resistant S. aureus (MRSA) lineages circulating throughout the U.S., vancomycin intermediate susceptible S. aureus (VISA), vancomycin resistant S. aureus (VRSA) and other Gram-positive bacterial pathogens with high RnpA amino acid conservation. We also found that this RnpA-inhibitor ameliorates disease in a systemic mouse infection model and has antimicrobial activity against biofilm-associated S. aureus. Taken together, these findings indicate that RnpA, either alone, as a component of the RNase P holoenzyme, and/or as a member of a more elaborate complex, may play a role in S. aureus RNA degradation and provide proof of principle for RNA catabolism-based antimicrobial therapy. The last decade has witnessed a mass downsizing in pharmaceutical antibiotic drug discovery initiatives. This has posed a major healthcare issue that will likely worsen with time; antibiotic resistant bacteria continue to emerge while advances in new therapeutic options languish. In the current body of work, we show that agents that limit bacterial RNA turnover have potential as a new class of antibiotics. More specifically, our findings indicate the essential bacterial protein, RnpA, exhibits in vitro ribonuclease activity and either alone and/or as a member of the RNase P holoenzyme, may contribute to the RNA degradation properties of Staphylococcus aureus, a predominant cause of hospital and community bacterial infections. Accordingly, using high throughput screening we identified small molecule inhibitors of RnpA's in vitro RNA degradation activity. One of these agents, RNPA1000, was shown to limit S. aureus mRNA turnover and growth. RNPA1000 also limited growth of other important Gram-positive bacterial pathogens, exhibited antimicrobial efficacy against biofilm associated S. aureus and protected against the S. aureus pathogenesis in an animal model of infection. When taken together, our results illustrate that components of the bacterial RNA degradation machinery have utility as antibiotic drug-discovery targets and that RNPA1000 may represent a progenitor of this new class of antibiotics.
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Affiliation(s)
- Patrick D. Olson
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Lisa J. Kuechenmeister
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Kelsi L. Anderson
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Sonja Daily
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Karen E. Beenken
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Christelle M. Roux
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Michelle L. Reniere
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Tami L. Lewis
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - William J. Weiss
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas, United States of America
| | - Mark Pulse
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas, United States of America
| | - Phung Nguyen
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas, United States of America
| | - Jerry W. Simecka
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas, United States of America
| | - John M. Morrison
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Khalid Sayood
- Department of Electrical Engineering, University of Nebraska, Lincoln, Nebraska, United States of America
| | - Oluwatoyin A. Asojo
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Mark S. Smeltzer
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Eric P. Skaar
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Paul M. Dunman
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- Department of Microbiology and Immunology, University of Rochester, Rochester, New York, United States of America
- * E-mail:
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Anderson KL, Roux CM, Olson MW, Luong TT, Lee CY, Olson R, Dunman PM. Characterizing the effects of inorganic acid and alkaline shock on the Staphylococcus aureus transcriptome and messenger RNA turnover. ACTA ACUST UNITED AC 2010; 60:208-50. [PMID: 21039920 DOI: 10.1111/j.1574-695x.2010.00736.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Staphylococcus aureus pathogenesis can be attributed partially to its ability to adapt to otherwise deleterious host-associated stresses. Here, Affymetrix GeneChips® were used to examine the S. aureus responses to inorganic acid and alkaline shock and to assess whether stress-dependent changes in mRNA turnover are likely to facilitate the organism's ability to tolerate a pH challenge. The results indicate that S. aureus adapts to pH shock by eliciting responses expected of cells coping with pH alteration, including neutralizing cellular pH, DNA repair, amino acid biosynthesis, and virulence factor expression. Further, the S. aureus response to alkaline conditions is strikingly similar to that of stringent response-induced cells. Indeed, we show that alkaline shock stimulates the accumulation of the stringent response activator (p)ppGpp. The results also revealed that pH shock significantly alters the mRNA properties of the cell. A comparison of the mRNA degradation properties of transcripts whose titers either increased or decreased in response to a sudden pH change revealed that alterations in mRNA degradation may, in part, account for the changes in the mRNA levels of factors predicted to mediate pH tolerance. A set of small stable RNA molecules were induced in response to acid- or alkaline-shock conditions and may mediate adaptation to pH stress.
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Affiliation(s)
- Kelsi L Anderson
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA
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Wyatt MA, Wang W, Roux CM, Beasley FC, Heinrichs DE, Dunman PM, Magarvey NA. Staphylococcus aureus nonribosomal peptide secondary metabolites regulate virulence. Science 2010; 329:294-6. [PMID: 20522739 DOI: 10.1126/science.1188888] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Staphylococcus aureus is a major human pathogen that is resistant to numerous antibiotics in clinical use. We found two nonribosomal peptide secondary metabolites--the aureusimines, made by S. aureus--that are not antibiotics, but function as regulators of virulence factor expression and are necessary for productive infections. In vivo mouse models of bacteremia showed that strains of S. aureus unable to produce aureusimines were attenuated and/or cleared from major organs, including the spleen, liver, and heart. Targeting aureusimine synthesis may offer novel leads for anti-infective drugs.
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Affiliation(s)
- Morgan A Wyatt
- Department of Biochemistry and Biomedical Sciences, M. G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
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Jacobs AC, Hood I, Boyd KL, Olson PD, Morrison JM, Carson S, Sayood K, Iwen PC, Skaar EP, Dunman PM. Inactivation of phospholipase D diminishes Acinetobacter baumannii pathogenesis. Infect Immun 2010; 78:1952-62. [PMID: 20194595 PMCID: PMC2863507 DOI: 10.1128/iai.00889-09] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 09/01/2009] [Accepted: 02/08/2010] [Indexed: 02/06/2023] Open
Abstract
Acinetobacter baumannii is an emerging bacterial pathogen of considerable health care concern. Nonetheless, relatively little is known about the organism's virulence factors or their regulatory networks. Septicemia and ventilator-associated pneumonia are two of the more severe forms of A. baumannii disease. To identify virulence factors that may contribute to these disease processes, genetically diverse A. baumannii clinical isolates were evaluated for the ability to proliferate in human serum. A transposon mutant library was created in a strain background that propagated well in serum and screened for members with decreased serum growth. The results revealed that disruption of A. baumannii phospholipase D (PLD) caused a reduction in the organism's ability to thrive in serum, a deficiency in epithelial cell invasion, and diminished pathogenesis in a murine model of pneumonia. Collectively, these results suggest that PLD is an A. baumannii virulence factor.
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Affiliation(s)
- Anna C. Jacobs
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6495, Department of Microbiology and Immunology, Department of Pathology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363, Department of Electrical Engineering, University of Nebraska, Lincoln, Nebraska 68588-0511
| | - Indriati Hood
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6495, Department of Microbiology and Immunology, Department of Pathology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363, Department of Electrical Engineering, University of Nebraska, Lincoln, Nebraska 68588-0511
| | - Kelli L. Boyd
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6495, Department of Microbiology and Immunology, Department of Pathology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363, Department of Electrical Engineering, University of Nebraska, Lincoln, Nebraska 68588-0511
| | - Patrick D. Olson
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6495, Department of Microbiology and Immunology, Department of Pathology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363, Department of Electrical Engineering, University of Nebraska, Lincoln, Nebraska 68588-0511
| | - John M. Morrison
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6495, Department of Microbiology and Immunology, Department of Pathology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363, Department of Electrical Engineering, University of Nebraska, Lincoln, Nebraska 68588-0511
| | - Steven Carson
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6495, Department of Microbiology and Immunology, Department of Pathology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363, Department of Electrical Engineering, University of Nebraska, Lincoln, Nebraska 68588-0511
| | - Khalid Sayood
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6495, Department of Microbiology and Immunology, Department of Pathology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363, Department of Electrical Engineering, University of Nebraska, Lincoln, Nebraska 68588-0511
| | - Peter C. Iwen
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6495, Department of Microbiology and Immunology, Department of Pathology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363, Department of Electrical Engineering, University of Nebraska, Lincoln, Nebraska 68588-0511
| | - Eric P. Skaar
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6495, Department of Microbiology and Immunology, Department of Pathology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363, Department of Electrical Engineering, University of Nebraska, Lincoln, Nebraska 68588-0511
| | - Paul M. Dunman
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6495, Department of Microbiology and Immunology, Department of Pathology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363, Department of Electrical Engineering, University of Nebraska, Lincoln, Nebraska 68588-0511
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Goering RV, Larsen AR, Skov R, Tenover FC, Anderson KL, Dunman PM. Comparative genomic analysis of European and Middle Eastern community-associated methicillin-resistant Staphylococcus aureus (CC80:ST80-IV) isolates by high-density microarray. Clin Microbiol Infect 2009; 15:748-55. [PMID: 19523053 DOI: 10.1111/j.1469-0691.2009.02850.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Infections as a result of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) are an issue of increasing global healthcare concern. In Europe, this principally involves strains of multi-locus sequence type clonal complex 80 sequence type 80 with methicillin resistance in a staphylococcal chromosomal cassette (SCCmec) type IV arrangement (CC80:ST80-IV). As with other CA-MRSA strains, CC80:ST80-IV isolates tend to appear uniform when analysed by common molecular typing methods (e.g. pulsed field gel electrophoresis, multi-locus sequence type, SCCmec). To explore whether DNA sequence-based differences exist, we compared the genetic composition of six CC80:ST80-IV isolates of diverse chronological and geographic origin (i.e. Denmark and the Middle East) using an Affymetrix high-density microarray that was previously used to analyse CA-MRSA USA300 isolates. The results revealed a high degree of homology despite the diversity in isolation date and origin, with isolate differences primarily in conserved hypothetical open reading frames and intergenic sequences, but also including regions of known function. This included the confirmed loss of SCCmec recombinase genes in two Danish isolates representing potentially new SCCmec types. Microarray analysis grouped the six isolates into three relatedness pairs, also identified by pulsed field gel electrophoresis, which were consistent with both the clinical and molecular data.
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Affiliation(s)
- R V Goering
- Deparatment of Medical Microbiology and Immunology, Creighton University School of Medicine, Omaha, NE 68178, USA.
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Chen PR, Nishida S, Poor CB, Cheng A, Bae T, Kuechenmeister L, Dunman PM, Missiakas D, He C. A new oxidative sensing and regulation pathway mediated by the MgrA homologue SarZ in Staphylococcus aureus. Mol Microbiol 2008; 71:198-211. [PMID: 19007410 DOI: 10.1111/j.1365-2958.2008.06518.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Oxidative stress serves as an important host/environmental signal that triggers a wide range of responses from the human pathogen Staphylococcus aureus. Among these, a thiol-based oxidation sensing pathway through a global regulator MgrA controls the virulence and antibiotic resistance of the bacterium. Herein, we report a new thiol-based oxidation sensing and regulation system that is mediated through a parallel global regulator SarZ. SarZ is a functional homologue of MgrA and is shown to affect the expression of approximately 87 genes in S. aureus. It uses a key Cys residue, Cys-13, to sense oxidative stress and to co-ordinate the expression of genes involved in metabolic switching, antibiotic resistance, peroxide stress defence, virulence, and cell wall properties. The discovery of this SarZ-mediated regulation, mostly independent from the MgrA-based regulation, fills a missing gap of oxidation sensing and response in S. aureus.
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Affiliation(s)
- Peng R Chen
- Department of Chemistry, 929 East 57th Street, The University of Chicago, Chicago, IL, USA
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Kuechenmeister LJ, Anderson KL, Morrison JM, Dunman PM. The use of molecular beacons to directly measure bacterial mRNA abundances and transcript degradation. J Microbiol Methods 2008; 76:146-51. [PMID: 18992285 DOI: 10.1016/j.mimet.2008.10.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 09/30/2008] [Accepted: 10/02/2008] [Indexed: 11/24/2022]
Abstract
The regulation of mRNA turnover is a dynamic means by which bacteria regulate gene expression. Although current methodologies allow characterization of the stability of individual transcripts, procedures designed to measure alterations in transcript abundance/turnover on a high throughput scale are lacking. In the current report, we describe the development of a rapid and simplified molecular beacon-based procedure to directly measure the mRNA abundances and mRNA degradation properties of well-characterized Staphylococcus aureus pathogenicity factors. This method does not require any PCR-based amplification, can monitor the abundances of multiple transcripts within a single RNA sample, and was successfully implemented into a high throughput screen of transposon mutant library members to detect isolates with altered mRNA turnover properties. It is expected that the described methodology will provide great utility in characterizing components of bacterial RNA degradation processes and can be used to directly measure the mRNA levels of virtually any bacterial transcript.
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Corbin BD, Seeley EH, Raab A, Feldmann J, Miller MR, Torres VJ, Anderson KL, Dattilo BM, Dunman PM, Gerads R, Caprioli RM, Nacken W, Chazin WJ, Skaar EP. Metal Chelation and Inhibition of Bacterial Growth in Tissue Abscesses. Science 2008; 319:962-5. [DOI: 10.1126/science.1152449] [Citation(s) in RCA: 652] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Torres VJ, Stauff DL, Pishchany G, Bezbradica JS, Gordy LE, Iturregui J, Anderson KL, Dunman PM, Joyce S, Skaar EP. A Staphylococcus aureus regulatory system that responds to host heme and modulates virulence. Cell Host Microbe 2007; 1:109-19. [PMID: 18005689 DOI: 10.1016/j.chom.2007.03.001] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Revised: 01/24/2007] [Accepted: 03/12/2007] [Indexed: 02/09/2023]
Abstract
Staphylococcus aureus, a bacterium responsible for tremendous morbidity and mortality, exists as a harmless commensal in approximately 25% of humans. Identifying the molecular machinery activated upon infection is central to understanding staphylococcal pathogenesis. We describe the heme sensor system (HssRS) that responds to heme exposure and activates expression of the heme-regulated transporter (HrtAB). Inactivation of the Hss or Hrt systems leads to increased virulence in a vertebrate infection model, a phenotype that is associated with an inhibited innate immune response. We suggest that the coordinated activity of Hss and Hrt allows S. aureus to sense internal host tissues, resulting in tempered virulence to avoid excessive host tissue damage. Further, genomic analyses have identified orthologous Hss and Hrt systems in Bacillus anthracis, Listeria monocytogenes, and Enterococcus faecalis, suggesting a conserved regulatory system by which Gram-positive pathogens sense heme as a molecular marker of internal host tissue and modulate virulence.
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Affiliation(s)
- Victor J Torres
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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Cassat J, Dunman PM, Murphy E, Projan SJ, Beenken KE, Palm KJ, Yang SJ, Rice KC, Bayles KW, Smeltzer MS. Transcriptional profiling of a Staphylococcus aureus clinical isolate and its isogenic agr and sarA mutants reveals global differences in comparison to the laboratory strain RN6390. Microbiology 2007; 152:3075-3090. [PMID: 17005987 DOI: 10.1099/mic.0.29033-0] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The production of Staphylococcus aureus virulence factors is under the control of complex regulatory circuits. Most studies aimed at defining these regulatory networks have focused on derivatives of the strain NCTC 8325, most notably RN6390. However, all NCTC 8325 derivatives, including RN6390, possess an 11 bp deletion in rsbU. This deletion renders NCTC 8325 derivatives naturally sigma-factor-B deficient. Recent studies have shown that RN6390 is also deficient, in comparison to clinical isolates, with respect to biofilm formation, a process which is important for both pathogenesis and antimicrobial resistance. Based on these considerations, the authors carried out genome-scale transcriptional profiling, comparing RN6390 with the virulent rsbU-positive clinical isolate UAMS-1. The results revealed significant genome-wide differences in expression patterns between RN6390 and UAMS-1, and suggested that the overall transcriptional profile of UAMS-1 is geared toward expression of factors that promote colonization and biofilm formation. In contrast, the transcriptional profile of RN6390 was heavily influenced by RNAIII expression, resulting in a phenotype characterized by increased production of exoproteins, and decreased capacity to form a biofilm. The greater influence of agr in RN6390 relative to UAMS-1 was also evident when the transcriptional profile of UAMS-1 was compared with that of its isogenic sarA and agr mutants. Specifically, the results indicate that, in contrast to NCTC 8325 derivatives, agr plays a limited role in overall regulation of gene expression in UAMS-1, when compared with sarA. Furthermore, by defining the sarA regulon in a biofilm-positive clinical isolate, and comparing the results with transcriptional profiling experiments defining biofilm-associated gene expression patterns in the same strain, the authors identified a sarA-regulated operon (alsSD) that is also induced in biofilms, and demonstrated that mutation of alsSD results in reduced capacity to form a biofilm.
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Affiliation(s)
- James Cassat
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Paul M Dunman
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | | | | | - Karen E Beenken
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Katherine J Palm
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Soo-Jin Yang
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Kelly C Rice
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Kenneth W Bayles
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Mark S Smeltzer
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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