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Shirley JD, Nauta KM, Gillingham JR, Diwakar S, Carlson EE. kinact / KI Value Determination for Penicillin-Binding Proteins in Live Cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.05.592586. [PMID: 38746240 PMCID: PMC11092749 DOI: 10.1101/2024.05.05.592586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Penicillin-binding proteins (PBPs) are an essential family of bacterial enzymes that are inhibited by the β-lactam class of antibiotics. PBP inhibition disrupts cell wall biosynthesis, which results in deficient growth and proliferation, and ultimately leads to lysis. IC 50 values are often employed as descriptors of enzyme inhibition and inhibitor selectivity but can be misleading in the study of time-dependent, irreversible inhibitors. Due to this disconnect, the second order rate constant k inact / K I is a more appropriate metric of covalent inhibitor potency. Despite being the gold standard measurement of potency, k inact / K I values are typically obtained from in vitro assays, which limits assay throughput if investigating an enzyme family with multiple homologs (such as the PBPs). Therefore, we developed a whole-cell k inact / K I assay to define inhibitor potency for the PBPs in Streptococcus pneumoniae using the fluorescent activity-based probe Bocillin-FL. Our results align with in vitro k inact / K I data and show a comparable relationship to previously established IC 50 values. These results support the validity of our in vivo k inact / K I method as a means of obtaining a full picture of β-lactam potency for a suite of PBPs. Abstract Figure
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Kang SM, Kim DH. Structural Insights into the Penicillin-Binding Protein 4 (DacB) from Mycobacterium tuberculosis. Int J Mol Sci 2024; 25:983. [PMID: 38256057 PMCID: PMC10815838 DOI: 10.3390/ijms25020983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/07/2024] [Accepted: 01/09/2024] [Indexed: 01/24/2024] Open
Abstract
Mycobacterium tuberculosis, a major cause of mortality from a single infectious agent, possesses a remarkable mycobacterial cell envelope. Penicillin-Binding Proteins (PBPs) are a family of bacterial enzymes involved in the biosynthesis of peptidoglycan. PBP4 (DacB) from M. tuberculosis (MtbPBP4) has been known to function as a carboxypeptidase, and the role and significance of carboxypeptidases as targets for anti-tuberculosis drugs or antibiotics have been extensively investigated over the past decade. However, their precise involvement remains incompletely understood. In this study, we employed predictive modeling and analyzed the three-dimensional structure of MtbPBP4. Interestingly, MtbPBP4 displayed a distinct domain structure compared to its homologs. Docking studies with meropenem verified the presence of active site residues conserved in PBPs. These findings establish a structural foundation for comprehending the molecular function of MtbPBP4 and offer a platform for the exploration of novel antibiotics.
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Affiliation(s)
- Sung-Min Kang
- College of Pharmacy, Duksung Women’s University, Seoul 01369, Republic of Korea
| | - Do-Hee Kim
- Jeju Research Institute of Pharmaceutical Sciences, College of Pharmacy, Jeju National University, Jeju 63243, Republic of Korea
- Interdisciplinary Graduate Program in Advanced Convergence Technology & Science, Jeju National University, Jeju 63243, Republic of Korea
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Panda AP, Pandey SD, Jain D, Ghosh AS. The MSMEG_1586 of M. smegmatis Is a Penicillin-Interactive Enzyme That Can Potentially Hydrolyse Aztreonam and Cephalosporins. Curr Microbiol 2023; 81:26. [PMID: 38041782 DOI: 10.1007/s00284-023-03545-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 10/30/2023] [Indexed: 12/03/2023]
Abstract
Mycobacteria are intrinsically resistant to beta-lactams as they possess several putative penicillin-interactive enzymes (PIEs), some of those are with dual-activity, namely DD-carboxypeptidase and beta-lactamase. Here, with help of molecular approaches, we elucidated the nature of one such putative PIE, MSMEG_1586, in Mycobacterium smegmatis. The in vivo expression of the membrane-bound form of MSMEG_1586 enhanced the beta-lactam resistance of a beta-lactamase deleted host E. coli strain (AM1OC), particularly for aztreonam (eight-fold) and cephalosporins (8-16 fold). To understand the reason for such elevation of resistance, soluble-form of MSMEG_1586 (sMSMEG_1586) was created by removing signal peptides and partially eliminating the amphipathic helix, and finally, expressed and purified. The purified sMSMEG_1586 was active and manifested a strong penicillin-binding affinity as shown by its ability to bind to fluorescent penicillin (Bocillin-FL). Interestingly, the steady-state kinetics apparently confirmed the hydrolytic ability of sMSMEG_1586 towards cefotaxime and aztreonam where hydrolysing aztreonam is a unique and rare behaviour among the beta-lactamases. However, sMSMEG_1586 was devoid of exerting DD-carboxypeptidase like activity. Finally, in silico analysis of MSMEG_1586 revealed a special folding that resembles class C beta-lactamase, except for the absence of a characteristic R2 loop. Overall, MSMEG_1586 could be categorized as a cephalosporinase with the ability to hydrolyse aztreonam.
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Affiliation(s)
- Aditya Prasad Panda
- Department of Biosciences and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India
| | - Satya Deo Pandey
- Department of Biosciences and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India
- Department of Oral Immunology and Infectious Diseases, School of Dentistry, University of Louisville, Louisville, KY, 40202, USA
| | - Diamond Jain
- Department of Biosciences and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India
| | - Anindya S Ghosh
- Department of Biosciences and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India.
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Jain D, Verma J, Ajith T, Bhattacharjee A, Ghosh AS. Two non-active site residues W165 and L166 prominently influence the beta-lactam hydrolytic ability of OXA-23 beta-lactamase. J Antibiot (Tokyo) 2023; 76:489-498. [PMID: 37095236 DOI: 10.1038/s41429-023-00624-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/28/2023] [Accepted: 04/02/2023] [Indexed: 04/26/2023]
Abstract
Dissemination of class D OXA-type carbapenemases is one of the significant causes of beta-lactam resistance in Gram-negative bacteria. The amino acid residues present near the active site are involved in hydrolytic mechanism of class D carbapenemases, though it is not identified in OXA-23. Here, with the help of site-directed mutagenesis, we aimed to explicate the importance of the residues W165, L166 and V167 of the possible omega loop and residue D222 in the short β5-β6 loop on the activity of OXA-23. All the residues were substituted with alanine. The resultant proteins were assayed for the changes in activity in E. coli cells and purified for in vitro activity, and stability assessment. E. coli cells harboring OXA-23_W165A and OXA-23_L166A, individually, exhibited a significant decrease in resistance towards beta-lactam antibiotics as compared to OXA-23. Further, purified OXA-23_W165A and OXA-23_L166A imparted about >4-fold decrease in catalytic efficiency and displayed reduced thermal stability as compared to OXA-23. Bocillin-FL binding assay revealed that W165A substitution results in improper N-carboxylation of K82, leading to deacylation deficient OXA-23. Therefore, we infer that the residue W165 maintains the integrity of N-carboxylated lysine (K82) of OXA-23 and the residue L166 might be responsible for properly orientating the antibiotic molecules.
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Affiliation(s)
- Diamond Jain
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, West Bengal, India
| | - Jyoti Verma
- Advanced Technology Development Centre, Indian Institute of Technology Kharagpur, Kharagpur, 721302, West Bengal, India
| | - Tejavath Ajith
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, West Bengal, India
| | | | - Anindya Sundar Ghosh
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, West Bengal, India.
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5
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Verma J, Jain D, Panda AP, Kant S, Kumar G, Ghosh AS. Involvement of the non-active site Residues in the Catalytic Activity of NDM-4 Metallo beta-lactamase. Protein J 2023:10.1007/s10930-023-10124-6. [PMID: 37170014 DOI: 10.1007/s10930-023-10124-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/07/2023] [Indexed: 05/13/2023]
Abstract
The rise of New Delhi metallo beta-lactamase (NDM) producing bacteria imposes a significant threat to the treatment of bacterial infections due to their broad spectrum against beta-lactams. The activity of metallo beta-lactamases is affected by active site residues as well as residues near the active site. Therefore, we aimed to identify the amino acid residues around the active site of NDM-4 which influence its function. To achieve that, seven substitution mutations (S191A, D192A, S213A, K216A, S217A, D223A and D225A) of NDM-4 were generated through site-directed mutagenesis. Out of these, expression of NDM-4_D192A and NDM-4_S217A in Escherichia coli cells increased the beta-lactam susceptibility as compared to NDM-4. Further, proteins were purified to assess the effect of substitution mutations on zinc content, in vitro catalytic efficiency, and stability of NDM-4. The catalytic efficiency was reduced for these mutants (D192A and S217A) towards beta-lactam substrates, while the thermal stability remained insubstantial as compared to NDM-4. However, the purified NDM-4_D192A exhibited altered zinc content. In silico studies reveal that these changes might be the outcomes of alterations in hydrogen bonding networks and substrate interactions. Taken together, we infer that the D192 and the S217 residues play a substantial role in the activity of NDM-4.
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Affiliation(s)
- Jyoti Verma
- Advanced Technology Development Centre, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India
| | - Diamond Jain
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India
| | - Aditya Prasad Panda
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India
| | - Shri Kant
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India
| | - Gaurav Kumar
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India
| | - Anindya Sundar Ghosh
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India.
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Antimicrobial Peptides Designed against the Ω-Loop of Class A β-Lactamases to Potentiate the Efficacy of β-Lactam Antibiotics. Antibiotics (Basel) 2023; 12:antibiotics12030553. [PMID: 36978420 PMCID: PMC10044640 DOI: 10.3390/antibiotics12030553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/02/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023] Open
Abstract
Class A serine β-lactamases (SBLs) have a conserved non-active site structural domain called the omega loop (Ω-loop), in which a glutamic acid residue is believed to be directly involved in the hydrolysis of β-lactam antibiotics by providing a water molecule during catalysis. We aimed to design and characterise potential pentapeptides to mask the function of the Ω-loop of β-lactamases and reduce their efficacy, along with potentiating the β-lactam antibiotics and eventually decreasing β-lactam resistance. Considering the Ω-loop sequence as a template, a group of pentapeptide models were designed, validated through docking, and synthesised using solid-phase peptide synthesis (SPPS). To check whether the β-lactamases (BLAs) were inhibited, we expressed specific BLAs (TEM-1 and SHV-14) and evaluated the trans-expression through a broth dilution method and an agar dilution method (HT-SPOTi). To further support our claim, we conducted a kinetic analysis of BLAs with the peptides and employed molecular dynamics (MD) simulations of peptides. The individual presence of six histidine-based peptides (TSHLH, ETHIH, ESRLH, ESHIH, ESRIH, and TYHLH) reduced β-lactam resistance in the strains harbouring BLAs. Subsequently, we found that the combinational effect of these peptides and β-lactams sensitised the bacteria towards the β-lactam drugs. We hypothesize that the antimicrobial peptides obtained might be considered among the novel inhibitors that can be used specifically against the Ω-loop of the β-lactamases.
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7
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Verma J, Jain D, Mallik D, Ghosh AS. Comparative insight into the roles of the non active-site residues E169 and N173 in imparting the beta-lactamase activity of CTX-M-15. FEMS Microbiol Lett 2022; 369:6530193. [PMID: 35175332 DOI: 10.1093/femsle/fnac018] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/03/2022] [Accepted: 02/15/2022] [Indexed: 11/13/2022] Open
Abstract
CTX-M-15 is a major extended-spectrum beta-lactamase disseminated throughout the globe. The roles of amino acids present in the active-site are widely studied though little is known about the role of the amino acids lying at the close proximity of the CTX-M-15 active-site. Here, by using site-directed mutagenesis we attempted to decipher the role of individual amino acids lying outside the active-site in imparting the beta-lactamase activity of CTX-M-15. Based on the earlier evidence, three amino acid residues namely, Glu169, Asp173 and Arg277 were substituted with alanine. The antibiotic susceptibility of E. coli cells harboring E169A and N173A substituted CTX-M-15 were enhanced by ∼ >32 fold for penicillins and ∼ 4-32 fold for cephalosporins, in comparison to CTX-M-15. However, cells carrying CTX-M-15_R277A did not show a significant difference in antibiotic susceptibility as compared to the wild-type. Further, the catalytic efficiency of the purified CTX-M-15_E169A and CTX-M-15_N173A were compromised when compared with the efficient beta-lactam hydrolysis of purified CTX-M-15. Moreover, the thermal stability of the mutated proteins CTX-M-15_E169A and CTX-M-15_N173A were reduced as compared to the wild type CTX-M-15. Therefore, we conclude that E169 and N173 are crucial non-active-site amino acids that are able to govern the CTX-M-15 activity.
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Affiliation(s)
- Jyoti Verma
- Advanced Technology Development Centre, Indian Institute of Technology Kharagpur, Kharagpur-721302, West Bengal, India
| | - Diamond Jain
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur-721302, West Bengal, India
| | - Dhriti Mallik
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur-721302, West Bengal, India
| | - Anindya S Ghosh
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur-721302, West Bengal, India
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8
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Papadopoulos AO, Ealand C, Gordhan BG, VanNieuwenhze M, Kana BD. Characterisation of a putative M23-domain containing protein in Mycobacterium tuberculosis. PLoS One 2021; 16:e0259181. [PMID: 34784363 PMCID: PMC8594824 DOI: 10.1371/journal.pone.0259181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 10/14/2021] [Indexed: 12/01/2022] Open
Abstract
Mycobacterium tuberculosis, the causative agent of tuberculosis remains a global health concern, further compounded by the high rates of HIV-TB co-infection and emergence of multi- and extensive drug resistant TB, all of which have hampered efforts to eradicate this disease. As a result, novel anti-tubercular interventions are urgently required, with the peptidoglycan component of the M. tuberculosis cell wall emerging as an attractive drug target. Peptidoglycan M23 endopeptidases can function as active cell wall hydrolases or degenerate activators of hydrolases in a variety of bacteria, contributing to important processes such as bacterial growth, division and virulence. Herein, we investigate the function of the Rv0950-encoded putative M23 endopeptidase in M. tuberculosis. In silico analysis revealed that this protein is conserved in mycobacteria, with a zinc-binding catalytic site predictive of hydrolytic activity. Transcript analysis indicated that expression of Rv0950c was elevated during lag and log phases of growth and reduced in stationary phase. Deletion of Rv0950c yielded no defects in growth, colony morphology, antibiotic susceptibility or intracellular survival but caused a reduction in cell length. Staining with a monopeptide-derived fluorescent D-amino acid, which spatially reports on sites of active PG biosynthesis or repair, revealed an overall reduction in uptake of the probe in ΔRv0950c. When stained with a dipeptide probe in the presence of cell wall damaging agents, the ΔRv0950c mutant displayed reduced sidewall labelling. As bacterial peptidoglycan metabolism is important for survival and pathogenesis, the role of Rv0950c and other putative M23 endopeptidases in M. tuberculosis should be explored further.
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Affiliation(s)
- Andrea Olga Papadopoulos
- Faculty of Health Sciences, DSI/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa
| | - Christopher Ealand
- Faculty of Health Sciences, DSI/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa
| | - Bhavna Gowan Gordhan
- Faculty of Health Sciences, DSI/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa
| | - Michael VanNieuwenhze
- Department of Chemistry, Indiana University Bloomington, Bloomington, Indiana, United States of America
| | - Bavesh Davandra Kana
- Faculty of Health Sciences, DSI/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa
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Fröhlich C, Chen JZ, Gholipour S, Erdogan AN, Tokuriki N. Evolution of β-lactamases and enzyme promiscuity. Protein Eng Des Sel 2021; 34:6294778. [PMID: 34100551 DOI: 10.1093/protein/gzab013] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/12/2021] [Accepted: 05/03/2021] [Indexed: 11/14/2022] Open
Abstract
β-Lactamases represent one of the most prevalent resistance mechanisms against β-lactam antibiotics. Beyond their clinical importance, they have also become key models in enzymology and evolutionary biochemistry. A global understanding of their evolution and sequence and functional diversity can therefore aid a wide set of different disciplines. Interestingly, β-lactamases have evolved multiple times from distinct evolutionary origins, with ancestries that reach back billions of years. It is therefore no surprise that these enzymes exhibit diverse structural features and enzymatic mechanisms. In this review, we provide a bird's eye view on the evolution of β-lactamases within the two enzyme superfamilies-i.e. the penicillin-binding protein-like and metallo-β-lactamase superfamily-through phylogenetics. We further discuss potential evolutionary origins of each β-lactamase class by highlighting signs of evolutionary connections in protein functions between β-lactamases and other enzymes, especially cases of enzyme promiscuity.
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Affiliation(s)
- Christopher Fröhlich
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, UiT The Arctic University of Norway, Tromsø 9037, Norway
| | - John Z Chen
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Sevan Gholipour
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Ayse N Erdogan
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Nobuhiko Tokuriki
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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First Penicillin-Binding Protein Occupancy Patterns for 15 β-Lactams and β-Lactamase Inhibitors in Mycobacterium abscessus. Antimicrob Agents Chemother 2020; 65:AAC.01956-20. [PMID: 33106266 DOI: 10.1128/aac.01956-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 10/21/2020] [Indexed: 02/06/2023] Open
Abstract
Mycobacterium abscessus causes serious infections that often require over 18 months of antibiotic combination therapy. There is no standard regimen for the treatment of M. abscessus infections, and the multitude of combinations that have been used clinically have had low success rates and high rates of toxicities. With β-lactam antibiotics being safe, double β-lactam and β-lactam/β-lactamase inhibitor combinations are of interest for improving the treatment of M. abscessus infections and minimizing toxicity. However, a mechanistic approach for building these combinations is lacking since little is known about which penicillin-binding protein (PBP) target receptors are inactivated by different β-lactams in M. abscessus We determined the preferred PBP targets of 13 β-lactams and 2 β-lactamase inhibitors in two M. abscessus strains and identified PBP sequences by proteomics. The Bocillin FL binding assay was used to determine the β-lactam concentrations that half-maximally inhibited Bocillin binding (50% inhibitory concentrations [IC50s]). Principal component analysis identified four clusters of PBP occupancy patterns. Carbapenems inactivated all PBPs at low concentrations (0.016 to 0.5 mg/liter) (cluster 1). Cephalosporins (cluster 2) inactivated PonA2, PonA1, and PbpA at low (0.031 to 1 mg/liter) (ceftriaxone and cefotaxime) or intermediate (0.35 to 16 mg/liter) (ceftazidime and cefoxitin) concentrations. Sulbactam, aztreonam, carumonam, mecillinam, and avibactam (cluster 3) inactivated the same PBPs as cephalosporins but required higher concentrations. Other penicillins (cluster 4) specifically targeted PbpA at 2 to 16 mg/liter. Carbapenems, ceftriaxone, and cefotaxime were the most promising β-lactams since they inactivated most or all PBPs at clinically relevant concentrations. These first PBP occupancy patterns in M. abscessus provide a mechanistic foundation for selecting and optimizing safe and effective combination therapies with β-lactams.
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Kandasamy S, Palaniyandi K, Gupta UD, Narayanan S. Double deletion of PknI/DacB2 leads to attenuation of Mycobacterium tuberculosis for growth and virulence. Tuberculosis (Edinb) 2020; 123:101957. [PMID: 32741534 DOI: 10.1016/j.tube.2020.101957] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 04/24/2020] [Accepted: 05/05/2020] [Indexed: 11/17/2022]
Abstract
Serine/Threonine Protein Kinases (STPKs) phosphorylates target proteins thereby regulates various important cellular signal transduction pathways such as cell division and cell wall synthesis. It has been demonstrated that the STPKs regulate peptidoglycan biosynthesis by phosphorylating penicillin binding proteins (PBPs). We extensively characterized both PknI (STPK) and DacB2 (PBP) roles individually as well as combining by genetic knockout and phenotypic characterization studies. In the present study, we analyzed the role of PknI and DacB2 in cell division and virulence. The double knockout (DKO) strain growth was reduced under stress conditions like acidic pH, nutrient depletion media and low oxygen availability conditions. We also found that the DKO growth was significantly reduced in macrophage cell line and it was hypersensitive to oxidative and nitrosative stress condition. The DKO strain significantly attenuated in guinea pig model which was measured by reduced bacillary load, gross pathological and histopathological damages. Overall, these results clearly demonstrated that both PknI and DacB2 together play an important role in cell division under stress conditions, the DKO strain significantly attenuated both in vitro and in vivo models.
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Affiliation(s)
- Srinivasan Kandasamy
- Department of Immunology, ICMR-National Institute for Research in Tuberculosis, Chennai, 600031, India
| | - Kannan Palaniyandi
- Department of Immunology, ICMR-National Institute for Research in Tuberculosis, Chennai, 600031, India
| | - Umesh Datta Gupta
- ICMR-National JALMA Institute for Leprosy and Other Mycobacterial Diseases, Agra, 282001, India
| | - Sujatha Narayanan
- Department of Immunology, ICMR-National Institute for Research in Tuberculosis, Chennai, 600031, India.
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12
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Thomas GH. Microbial Musings – June 2020. Microbiology (Reading) 2020; 166:498-500. [PMID: 32633711 PMCID: PMC7376269 DOI: 10.1099/mic.0.000951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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13
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Pandey SD, Jain D, Kumar N, Adhikary A, Kumar N G, Ghosh AS. MSMEG_2432 of Mycobacterium smegmatis mc 2155 is a dual function enzyme that exhibits DD-carboxypeptidase and β-lactamase activities. MICROBIOLOGY-SGM 2020; 166:546-553. [PMID: 32301689 DOI: 10.1099/mic.0.000902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mycobacterial peptidoglycan (PG) is an unsolved puzzle due to its complex structure and involvement of multiple enzymes in the process of its remodelling. dd-Carboxypeptidases are low molecular mass penicillin-binding proteins (LMM-PBPs) that catalyzes the cleavage of terminal d-Ala of muramyl pentapeptide branches and thereby helps in the PG remodelling process. Here, we have assigned the function of a putative LMM-PBP, MSMEG_2432 of Mycobacterium smegmatis, by showing that it exhibits both dd-CPase and β-lactamase activities. Like conventional dd-CPase (PBP5 from E. coli), upon ectopic complementation in a deformed seven PBP deletion mutant of E. coli, MSMEG_2432 has manifested its ability to restore ~75 % of the cell population to their normal rod shape. Further, in vitrodd-CPase assay has confirmed its ability to release terminal d-Ala from the synthetic tripeptide and the peptidoglycan mimetic pentapeptide substrates ending with d-Ala-d-Ala. Also, elevated resistance against penicillins and cephalosporins upon ectopic expression of MSMEG_2432 suggests the presence of β-lactamase activity, which is further confirmed in vitro through nitrocefin hydrolysis assay. Moreover, it is found apparent that D169A substitution in MSMEG_2432 influences both of its in vivo and in vitrodd-CPase and β-lactamase activities. Thus, we infer that MSMEG_2432 is a dual function enzyme that possesses both dd-CPase and β-lactamase activities.
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Affiliation(s)
- Satya Deo Pandey
- University of Kansas Medical Center, USA.,Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal PIN-721302, India
| | - Diamond Jain
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal PIN-721302, India
| | - Neeraj Kumar
- Centre for DNA fingerprinting & Diagnostics, India.,Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal PIN-721302, India
| | - Anwesha Adhikary
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal PIN-721302, India
| | - Ganesh Kumar N
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal PIN-721302, India
| | - Anindya S Ghosh
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal PIN-721302, India
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Abdullah SM, Rachid S. On Column Binding a Real-Time Biosensor for β-lactam Antibiotics Quantification. Molecules 2020; 25:molecules25051248. [PMID: 32164217 PMCID: PMC7179420 DOI: 10.3390/molecules25051248] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 03/04/2020] [Accepted: 03/05/2020] [Indexed: 02/07/2023] Open
Abstract
This work aimed to develop accurate, quick, and practical tools for the detection of residues of penicillin G antibiotic in biological and non-biological samples. The assays were developed based on the binding mechanism of β-lactam to penicillin-binding proteins; samples of different concentrations of penicillin G were incubated with in vitro expressed 6X-Histidine-tagged soluble penicillin-binding protein (PBP2x*) of Streptococcus pneumoniae (S. pneumoniae), whereby penicillin G in samples specifically binds to PBP2x*. The fluorescent-labeled β-lactam analogue Bocillin FL was used as a competent substrate, and two different routes estimated the amounts of the penicillin G. The first route was established based on the differences in the concentration of non-bounded Bocillin FL molecules within the reactions while using a real-time polymerase chain reaction (PCR)-based method for fluorescence detection. The second route depended on the amount of the relative intensity of Bocillin FL bounded to Soluble PBP-2x*, being run on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-page), visualized by a ChemiDoc-It®2 Imager, and quantified based on the fluorescence affinity of the competent substrate. While both of the methods gave a broad range of linearity and high sensitivity, the on column based real-time method is fast, non-time consuming, and highly sensitive. The method identified traces of antibiotic in the range 0.01-0.2 nM in addition to higher accuracy in comparison to the SDS-based detection method, while the sensitivity of the SDS-based method ranged between 0.015 and 2 µM). Thus, the on column based real time assay is a fast novel method, which was developed for the first time based on the binding inhibition of a fluorescence competitor material and it can be adapted to screen traces of penicillin G in any biological and environmental samples.
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Affiliation(s)
- Shahla M. Abdullah
- Medical Laboratory Science Department, College of Science, University of Raparin, Ranyia 46012, Sulaymaniyah, Iraq;
- Biology Department, Faculty of Science and Health, Koya University, Koysanjaq 44023, Erbil, Iraq
| | - Shwan Rachid
- Charmo Center for Research, Training, and Consultancy, Charmo University, Chamchamal 46023, Sulaymaniyah, Iraq
- Correspondence: ; Tel.: +0964-7701494344
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15
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Kumar G, Issa B, Biswal S, Jain D, Bhattacharjee A, Ghosh AS. Glutamic acid at position 152 and serine at position 191 are key residues required for the metallo-β-lactamase activity of NDM-7. Int J Antimicrob Agents 2020; 55:105824. [DOI: 10.1016/j.ijantimicag.2019.10.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 09/13/2019] [Accepted: 10/11/2019] [Indexed: 10/25/2022]
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16
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Mallick S, Das J, Verma J, Mathew S, Maiti TK, Ghosh AS. Role of Escherichia coli endopeptidases and dd-carboxypeptidases in infection and regulation of innate immune response. Microbes Infect 2019; 21:464-474. [PMID: 31085336 DOI: 10.1016/j.micinf.2019.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 04/21/2019] [Accepted: 04/23/2019] [Indexed: 01/13/2023]
Abstract
The low-molecular-mass penicillin-binding proteins, involved in peptidoglycan recycling can also produce peptidoglycan fragments capable of activating an innate immune response in host. To investigate how these proteins in Enterobacteriaceae play a role to elicit/evade innate immune responses during infections, we deleted certain endopeptidases and dd-carboxypeptidases from Escherichia coli CS109 and studied the viability of these mutants in macrophages. The ability of infected macrophages to exert oxidative killing, express surface activation markers TLR2, MHC class II and release TNFα, were assessed. Immune responses were elevated in macrophages infected with dd-carboxypeptidase mutants but reduced for endopeptidase mutants. However, the NFκB, iNOS, and TLR2 transcripts remained elevated in macrophages infected with both mutant types. Overall, we have shown, under normal conditions endopeptidases have a tendency to elicit the immune response but their effect is suppressed by the presence of dd-carboxypeptidases. Conversely, DD-carboxypeptidases, normally, tend to reduce immune responses, as their deletions enhanced the same in macrophages. Therefore, we conclude that the roles of endopeptidases and dd-carboxypeptidases are possibly counter-active in wild-type cells where either class of enzymes suppresses each other's immunogenic properties rendering overall maintenance of low immunogenicity that helps E. coli in evading the host immune responses.
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Affiliation(s)
- Sathi Mallick
- Department of Biotechnology, Indian Institute of Technology Kharagpur, West Bengal, 721302, India
| | - Joyjyoti Das
- Department of Biotechnology, Indian Institute of Technology Kharagpur, West Bengal, 721302, India
| | - Jyoti Verma
- Advanced Technology Development Centre, Indian Institute of Technology Kharagpur, West Bengal, 721302, India
| | - Samatha Mathew
- Department of Biotechnology, Indian Institute of Technology Kharagpur, West Bengal, 721302, India
| | - Tapas K Maiti
- Department of Biotechnology, Indian Institute of Technology Kharagpur, West Bengal, 721302, India
| | - Anindya S Ghosh
- Department of Biotechnology, Indian Institute of Technology Kharagpur, West Bengal, 721302, India.
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17
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Ealand CS, Asmal R, Mashigo L, Campbell L, Kana BD. Characterization of putative DD-carboxypeptidase-encoding genes in Mycobacterium smegmatis. Sci Rep 2019; 9:5194. [PMID: 30914728 PMCID: PMC6435803 DOI: 10.1038/s41598-019-41001-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 02/22/2019] [Indexed: 01/21/2023] Open
Abstract
Penicillin binding proteins (PBPs) are the target of numerous antimicrobial agents that disrupt bacterial cell wall synthesis. In mycobacteria, cell elongation occurs through insertion of nascent cell wall material in the sub-polar region, a process largely driven by High Molecular Weight PBPs. In contrast, the function of DD-carboxypeptidases (DD-CPases), which are Low Molecular Weight Class 1C PBPs, in mycobacteria remains poorly understood. Mycobacterium smegmatis encodes four putative DD-CPase homologues, which display homology to counterparts in Escherichia coli. Herein, we demonstrate that these are expressed in varying abundance during growth. Deletion of MSMEG_1661, MSMEG_2433 or MSMEG_2432, individually resulted in no defects in growth, cell morphology, drug susceptibility or spatial incorporation of new peptidoglycan. In contrast, deletion of MSMEG_6113 (dacB) was only possible in a merodiploid strain expressing the homologous M. tuberculosis operon encoding Rv3627c (dacB), Rv3626c, Rv3625c (mesJ) and Rv3624c (hpt), suggestive of essentiality. To investigate the role of this operon in mycobacterial growth, we depleted gene expression using anhydrotetracycline-responsive repressors and noted reduced bipolar peptidoglycan synthesis. These data point to a possible role for this four gene operon, which is highly conserved across all mycobacterial species, in regulating spatial localization of peptidoglycan synthesis.
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Affiliation(s)
- Christopher S Ealand
- DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, P.O. Box 1038, Johannesburg, 2000, South Africa
| | - Rukaya Asmal
- DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, P.O. Box 1038, Johannesburg, 2000, South Africa
| | - Lethabo Mashigo
- DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, P.O. Box 1038, Johannesburg, 2000, South Africa
| | - Lisa Campbell
- DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, P.O. Box 1038, Johannesburg, 2000, South Africa
| | - Bavesh D Kana
- DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, P.O. Box 1038, Johannesburg, 2000, South Africa.
- MRC-CAPRISA HIV-TB Pathogenesis and Treatment Research Unit, Centre for the AIDS Programme of Research in South Africa, CAPRISA, Durban, South Africa.
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18
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Abstract
Actinobacteria is a group of diverse bacteria. Most species in this class of bacteria are filamentous aerobes found in soil, including the genus Streptomyces perhaps best known for their fascinating capabilities of producing antibiotics. These bacteria typically have a Gram-positive cell envelope, comprised of a plasma membrane and a thick peptidoglycan layer. However, there is a notable exception of the Corynebacteriales order, which has evolved a unique type of outer membrane likely as a consequence of convergent evolution. In this chapter, we will focus on the unique cell envelope of this order. This cell envelope features the peptidoglycan layer that is covalently modified by an additional layer of arabinogalactan . Furthermore, the arabinogalactan layer provides the platform for the covalent attachment of mycolic acids , some of the longest natural fatty acids that can contain ~100 carbon atoms per molecule. Mycolic acids are thought to be the main component of the outer membrane, which is composed of many additional lipids including trehalose dimycolate, also known as the cord factor. Importantly, a subset of bacteria in the Corynebacteriales order are pathogens of human and domestic animals, including Mycobacterium tuberculosis. The surface coat of these pathogens are the first point of contact with the host immune system, and we now know a number of host receptors specific to molecular patterns exposed on the pathogen's surface, highlighting the importance of understanding how the cell envelope of Actinobacteria is structured and constructed. This chapter describes the main structural and biosynthetic features of major components found in the actinobacterial cell envelopes and highlights the key differences between them.
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Affiliation(s)
- Kathryn C Rahlwes
- Department of Microbiology, University of Massachusetts, 639 North Pleasant Street, Amherst, MA, 01003, USA
| | - Ian L Sparks
- Department of Microbiology, University of Massachusetts, 639 North Pleasant Street, Amherst, MA, 01003, USA
| | - Yasu S Morita
- Department of Microbiology, University of Massachusetts, 639 North Pleasant Street, Amherst, MA, 01003, USA.
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19
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Elitas M. On-Chip Isoniazid Exposure of Mycobacterium smegmatis Penicillin-Binding Protein (PBP) Mutant Using Time-Lapse Fluorescent Microscopy. MICROMACHINES 2018; 9:mi9110561. [PMID: 30715060 PMCID: PMC6266593 DOI: 10.3390/mi9110561] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 10/26/2018] [Accepted: 10/27/2018] [Indexed: 01/08/2023]
Abstract
Antibiotic resistance has been one of the biggest threats to global health. Despite the available prevention and control strategies and efforts in developing new antibiotics, the need remains for effective approaches against antibiotic resistance. Efficient strategies to cope with antimicrobial resistance require a quantitative and deeper understanding of microbial behavior, which can be obtained using different techniques to provide the missing pieces of the current antibiotic-resistance puzzle. Microfluidic-microscopy techniques are among the most promising methods that contribute modernization of traditional assays in microbiology. They provide monitoring and manipulation of cells at micro-scale volumes. Here, we combined population-level, culture-based assays with single-cell resolution, microfluidic-microscopy systems to investigate isoniazid response of Mycobacterium smegmatis penicillin-binding protein (PBP) mutant. This mutant exhibited normal growth in plain medium and sensitivity to stress responses when treated with thermal stress (45 °C), detergent stress (0.1% sodium dodecyl sulfate), acid stress (pH 4.5), and nutrient starvation (1XPBS). The impact of msm0031 transposon insertion on drug-mediated killing was determined for isoniazid (INH, 50 µg/mL), rifampicin (RIF, 200 µg/mL), ethionamide (ETH, 200 µg/mL), and ethambutol (EMB, 5 µg/mL). The PBP mutant demonstrated remarkable isoniazid-killing phenotype in batch culture. Therefore, we hypothesized that single-cell analysis will show increased lysis kinetics and fewer intact cells after drug treatment. However, the single-cell analysis data showed that upon isoniazid exposure, the percentage of the intact PBP mutant cells was 24%, while the percentage of the intact wild-type cells was 4.6%. The PBP mutant cells exhibited decreased cell-lysis profile. Therefore, the traditional culture-based assays were not sufficient to provide insights about the subpopulation of viable but non-culture cells. Consequently, we need more adequate tools to be able to comprehend and fight the antibiotic resistance of bacteria.
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Affiliation(s)
- Meltem Elitas
- Faculty of Engineering and Natural Sciences, Sabanci University, Tuzla, 34956 Istanbul, Turkey.
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20
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Baranowski C, Welsh MA, Sham LT, Eskandarian HA, Lim HC, Kieser KJ, Wagner JC, McKinney JD, Fantner GE, Ioerger TR, Walker S, Bernhardt TG, Rubin EJ, Rego EH. Maturing Mycobacterium smegmatis peptidoglycan requires non-canonical crosslinks to maintain shape. eLife 2018; 7:37516. [PMID: 30324906 PMCID: PMC6231781 DOI: 10.7554/elife.37516] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 10/11/2018] [Indexed: 01/06/2023] Open
Abstract
In most well-studied rod-shaped bacteria, peptidoglycan is primarily crosslinked by penicillin-binding proteins (PBPs). However, in mycobacteria, crosslinks formed by L,D-transpeptidases (LDTs) are highly abundant. To elucidate the role of these unusual crosslinks, we characterized Mycobacterium smegmatis cells lacking all LDTs. We find that crosslinks generate by LDTs are required for rod shape maintenance specifically at sites of aging cell wall, a byproduct of polar elongation. Asymmetric polar growth leads to a non-uniform distribution of these two types of crosslinks in a single cell. Consequently, in the absence of LDT-mediated crosslinks, PBP-catalyzed crosslinks become more important. Because of this, Mycobacterium tuberculosis (Mtb) is more rapidly killed using a combination of drugs capable of PBP- and LDT- inhibition. Thus, knowledge about the spatial and genetic relationship between drug targets can be exploited to more effectively treat this pathogen. Most bacteria have a cell wall that protects them and maintains their shape. Many of these organisms make their cell walls from fibers of proteins and sugars, called peptidoglycan. As bacteria grow, peptidoglycan is constantly broken down and reassembled, and in many species, new units of peptidoglycan are added into the sidewall. However, in a group of bacteria called mycobacteria, which cause tuberculosis and other diseases, the units are added at the tips. The peptidoglycan layer is often a successful target for antibiotic treatments. But, drugs that treat tuberculosis do not attack this layer, partly because we know very little about the cell walls of mycobacteria. Here, Baranowski et al. used genetic manipulation and microscopy to study how mycobacteria build their cell wall. The results showed that these bacteria link peptidoglycan units together in an unusual way. In most bacteria, peptidoglycan units are connected by chemical links known as 4-3 crosslinks. This is initially the same in mycobacteria, but as the cell grows and the cell wall expands, these bonds break and so-called 3-3 crosslinks form. In genetically modified bacteria that could not form these 3-3 bonds, the cell wall became brittle and weak, and the bacteria eventually died. These findings could be important for developing new drugs that treat infections caused by mycobacteria. Baranowski et al. demonstrate that a combination of drugs blocking both 4-3 and 3-3 crosslinks is particularly effective at killing the bacterium that causes tuberculosis.
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Affiliation(s)
- Catherine Baranowski
- Department of Immunology and Infectious Disease, Harvard TH Chan School of Public Health, Boston, United States
| | - Michael A Welsh
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States
| | - Lok-To Sham
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States.,Department of Microbiology and Immunology, National University of Singapore, Singapore, Singapore
| | - Haig A Eskandarian
- School of Life Sciences, Swiss Federal Institute of Technology in Lausanne, Lausanne, Switzerland.,School of Engineering, Swiss Federal Institute of Technology in Lausanne, Lausanne, Switzerland
| | - Hoong Chuin Lim
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States
| | - Karen J Kieser
- Department of Immunology and Infectious Disease, Harvard TH Chan School of Public Health, Boston, United States
| | - Jeffrey C Wagner
- Department of Immunology and Infectious Disease, Harvard TH Chan School of Public Health, Boston, United States
| | - John D McKinney
- School of Life Sciences, Swiss Federal Institute of Technology in Lausanne, Lausanne, Switzerland
| | - Georg E Fantner
- School of Engineering, Swiss Federal Institute of Technology in Lausanne, Lausanne, Switzerland
| | - Thomas R Ioerger
- Department of Computer Science and Engineering, Texas A&M University, Texas, United States
| | - Suzanne Walker
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States
| | - Thomas G Bernhardt
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States
| | - Eric J Rubin
- Department of Immunology and Infectious Disease, Harvard TH Chan School of Public Health, Boston, United States.,Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States
| | - E Hesper Rego
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, United States
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21
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Two dd-Carboxypeptidases from Mycobacterium smegmatis Affect Cell Surface Properties through Regulation of Peptidoglycan Cross-Linking and Glycopeptidolipids. J Bacteriol 2018; 200:JB.00760-17. [PMID: 29735762 DOI: 10.1128/jb.00760-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 04/25/2018] [Indexed: 11/20/2022] Open
Abstract
During the peptidoglycan (PG) maturation of mycobacteria, the glycan strands are interlinked by both 3-3 (between two meso-diaminopimelic acids [meso-DAPs]) and 4-3 cross-links (between d-Ala and meso-DAP), though there is a predominance (60 to 80%) of 3-3 cross-links. The dd-carboxypeptidases (dd-CPases) act on pentapeptides to generate tetrapeptides that are used by ld-transpeptidases as substrates to form 3-3 cross-links. Therefore, dd-CPases play a crucial role in mycobacterial PG cross-link formation. However, the physiology of dd-CPases in mycobacteria is relatively unexplored. In this study, we deleted two dd-CPase genes, msmeg_2433 and msmeg_2432, both individually and in combination, from Mycobacterium smegmatis mc2155. Though the single dd-CPase gene deletions had no significant impact on the mycobacterial physiology, many interesting functional alterations were observed in the double-deletion mutant, viz, a predominance in PG cross-link formation was shifted from 3-3 cross-links to 4-3, cell surface glycopeptidolipid (GPL) expression was reduced, and susceptibility to β-lactams and antitubercular agents was enhanced. Moreover, the survival rate of the double mutant within murine macrophages was higher than that of the parent. Interestingly, the complementation with any one of the dd-CPase genes could restore the wild-type phenotype. In a nutshell, we infer that the altered ratio of 4-3 to 3-3 PG cross-links might have influenced the expression of surface GPLs, colony morphology, biofilm formation, drug susceptibility, and subsistence of the cells within macrophages.IMPORTANCE The glycan strands in mycobacterial peptidoglycan (PG) are interlinked by both 3-3 and 4-3 cross-links. The dd-CPases generate tetrapeptides by acting on the pentapeptides, and ld-transpeptidases use tetrapeptides as substrates to form 3-3 cross-links. In this study, we showed that simultaneous deletions of two dd-CPases alter the nature of PG cross-linking from 3-3 cross-links to 4-3 cross-links. The deletions subsequently decrease the expression of glycopeptidolipids (significant surface lipid present in many nontuberculous mycobacteria, including Mycobacterium smegmatis) and affect other physiological parameters, like cell morphology, growth rate, biofilm formation, antibiotic susceptibility, and survival within murine macrophages. Thus, unraveling the physiology of dd-CPases might help us design antimycobacterial therapeutics in the future.
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22
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Kar D, Pandey SD, Mallick S, Dutta M, Ghosh AS. Substitution of Alanine at Position 184 with Glutamic Acid in Escherichia coli PBP5 Ω-Like Loop Introduces a Moderate Cephalosporinase Activity. Protein J 2018; 37:122-131. [DOI: 10.1007/s10930-018-9765-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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Kumar G, Biswal S, Nathan S, Ghosh AS. Glutamate residues at positions 162 and 164 influence the beta-lactamase activity of SHV-14 obtained from Klebsiella pneumoniae. FEMS Microbiol Lett 2018; 365:4705895. [PMID: 29228168 DOI: 10.1093/femsle/fnx259] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 11/29/2017] [Indexed: 11/13/2022] Open
Abstract
Extensive production of SHV-14 beta-lactamase makes Klebsiella pneumoniae resistant to beta-lactams. The presence of omega-loop has been reported to influence the beta-lactamase activity, which is also present in SHV-14. Its omega-loop has three glutamates in nearly alternating positions 162, 164 and 167 but their concise role on the behaviour of SHV-14 is unknown. To uncover the influence of each glutamate on SHV-14, we replaced glutamates with alanine and estimated the effect of each mutation by assessing the change in beta-lactam sensitivities in the surrogate Escherichia coli cells and catalytic efficiencies for hydrolysis with the purified proteins. On expression, the clone of wild-type SHV-14 aggravated the resistance of host by 60-500 folds against penicillin and cephalosporin groups of antibiotics. However, the expression of mutated enzymes (especially E164A) substantially reduced the resistance level as compared to the wild type, and the results were in synchrony with the estimated enzymatic efficiencies of wild-type and mutated proteins. Therefore, with further support from the in silico analysis, we hypothesise that mutation at the glutamate residues in the omega-loop of SHV-14 can considerably modulate the beta-lactam sensitivity and hydrolysis, thus revealing the importance of such glutamates as the target for inhibitor design in future.
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Affiliation(s)
- Gaurav Kumar
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal - 721302, India
| | - Sarmistha Biswal
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal - 721302, India
| | - Soshina Nathan
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal - 721302, India
| | - Anindya S Ghosh
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal - 721302, India
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24
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Bansal A, Kar D, Pandey SD, Matcha A, Kumar NG, Nathan S, Ghosh AS. A Tyrosine Residue Along with a Glutamic Acid of the Omega-Like Loop Governs the Beta-Lactamase Activity of MSMEG_4455 in Mycobacterium smegmatis. Protein J 2017; 36:220-227. [PMID: 28421415 DOI: 10.1007/s10930-017-9713-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mycobacterial beta-lactamases are involved in exerting beta-lactam resistance, though many of these proteins remain uncharacterized. Here, we have characterized MSMEG_4455 of Mycobacterium smegmatis as a beta-lactamase using molecular, biochemical and mutational techniques. To elucidate its nature in vivo and in vitro, and to predict its structure-function relationship in silico analysis is done. The MSMEG_4455 is cloned and expressed ectopically in a beta-lactamase deficient Escherichia coli mutant to establish the in vivo beta-lactamase like nature via minimum inhibitory concentration (MIC) determination. Likewise the in vivo results, purified soluble form of MSMEG_4455 showed beta-lactam hydrolysis pattern similar to group 2a penicillinase. In silico analyses of MSMEG_4455 reveal glutamic acid (E)193 and tyrosine (Y)194 of omega-like loop might have importance in strengthening hydrogen bond network around the active-site, though involvement of tyrosine is rare for beta-lactamase activity. Accordingly, these residues are mutated to alanine (A) and phenylalanine (F), respectively. The mutated proteins have partially lost their ability to exert beta-lactamase activity both in vivo and in vitro. The Y194F mutation had more prominent effect on the enzymatic activity. Therefore, we infer that Y194 is the key for beta-lactamase activity of MSMEG_4455.
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Affiliation(s)
- Ankita Bansal
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal, 721302, India
| | - Debasish Kar
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal, 721302, India
| | - Satya Deo Pandey
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal, 721302, India
| | - Ashok Matcha
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal, 721302, India
| | - N Ganesh Kumar
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal, 721302, India
| | - Soshina Nathan
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal, 721302, India
| | - Anindya S Ghosh
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal, 721302, India.
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25
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Singha M, Roy S, Pandey SD, Bag SS, Bhattacharya P, Das M, Ghosh AS, Ray D, Basak A. Use of azidonaphthalimide carboxylic acids as fluorescent templates with a built-in photoreactive group and a flexible linker simplifies protein labeling studies: applications in selective tagging of HCAII and penicillin binding proteins. Chem Commun (Camb) 2017; 53:13015-13018. [DOI: 10.1039/c7cc08209f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A simple design of versatile template-based protein labeling agents has been successfully demonstrated with HCA and PBPs.
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Affiliation(s)
- Monisha Singha
- Department of Chemistry
- Indian Institute of Technology Kharagpur
- India
| | - Sayantani Roy
- School of Bioscience
- Indian Institute of Technology Kharagpur
- India
| | - Satya Deo Pandey
- Department of Biotechnology
- Indian Institute of Technology Kharagpur
- India
| | | | | | - Mainak Das
- Department of Chemistry
- Indian Institute of Technology Kharagpur
- India
| | - Anindya S. Ghosh
- Department of Biotechnology
- Indian Institute of Technology Kharagpur
- India
| | - Debashis Ray
- Department of Chemistry
- Indian Institute of Technology Kharagpur
- India
| | - Amit Basak
- Department of Chemistry
- Indian Institute of Technology Kharagpur
- India
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26
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Bansal A, Mallik D, Kar D, Ghosh AS. Identification of a multidrug efflux pump in Mycobacterium smegmatis. FEMS Microbiol Lett 2016; 363:fnw128. [PMID: 27190152 DOI: 10.1093/femsle/fnw128] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2016] [Indexed: 12/21/2022] Open
Abstract
Cell wall impermeability and active efflux of drugs are among the primary reasons for drug resistance in mycobacteria. Efflux pumps are tripartite membrane localized transport proteins that expel drug molecules outside the cells. Several of such efflux pumps are annotated in mycobacteria, but few have been characterized, like MSMEG_2991, a putative efflux pump permease of Mycobacterium smegmatis To substantiate this, we overexpressed MSMEG_2991 protein in Escherichia coli 2443. Expression of MSMEG_2991 elevated the resistance towards structurally unrelated groups of antibiotics. An active antibiotic efflux pump nature of MSMEG_2991 was revealed by assessing the acquisition of ciprofloxacin in the absence and presence of the efflux pump inhibitor, carbonyl cyanide m-chlorophenyl hydrazone, indicating the involvement of proton-motive force (pmf) during the efflux activity. MSMEG_2991 expression elevated biofilm formation in E. coli by 4-fold, keeping parity to some of the earlier reported efflux pumps. In silico analysis suggested the presence of 12 transmembrane helices in MSMEG_2991 resembling EmrD efflux pump of E. coli Based on in vivo and in silico analyses, MSMEG_2991 may be designated as a pmf-mediated multidrug efflux pump protein that expels diverse groups of antibiotics and might as well be involved in the biofilm enhancement.
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Affiliation(s)
- Ankita Bansal
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal 721302, India
| | - Dhriti Mallik
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal 721302, India
| | - Debasish Kar
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal 721302, India
| | - Anindya S Ghosh
- Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal 721302, India
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Fisher JF, Mobashery S. β-Lactam Resistance Mechanisms: Gram-Positive Bacteria and Mycobacterium tuberculosis. Cold Spring Harb Perspect Med 2016; 6:cshperspect.a025221. [PMID: 27091943 DOI: 10.1101/cshperspect.a025221] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The value of the β-lactam antibiotics for the control of bacterial infection has eroded with time. Three Gram-positive human pathogens that were once routinely susceptible to β-lactam chemotherapy-Streptococcus pneumoniae, Enterococcus faecium, and Staphylococcus aureus-now are not. Although a fourth bacterium, the acid-fast (but not Gram-positive-staining) Mycobacterium tuberculosis, has intrinsic resistance to earlier β-lactams, the emergence of strains of this bacterium resistant to virtually all other antibiotics has compelled the evaluation of newer β-lactam combinations as possible contributors to the multidrug chemotherapy required to control tubercular infection. The emerging molecular-level understanding of these resistance mechanisms used by these four bacteria provides the conceptual framework for bringing forward new β-lactams, and new β-lactam strategies, for the future control of their infections.
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Affiliation(s)
- Jed F Fisher
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670
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Shapiro AB. Investigation of β-lactam antibacterial drugs, β-lactamases, and penicillin-binding proteins with fluorescence polarization and anisotropy: a review. Methods Appl Fluoresc 2016; 4:024002. [DOI: 10.1088/2050-6120/4/2/024002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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