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Scott C, Dias AP, De Buck J. Adherence and metal-ion acquisition gene expression increases during infection with Treponema phagedenis strains from bovine digital dermatitis. Infect Immun 2024:e0011724. [PMID: 38940601 DOI: 10.1128/iai.00117-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Accepted: 05/16/2024] [Indexed: 06/29/2024] Open
Abstract
Digital dermatitis (DD) is an ulcerative foot lesion on the heel bulbs of dairy cattle. DD is a polymicrobial disease with no precise etiology, although Treponema spirochetes are found disproportionally abundant in diseased tissue. Within Treponema, several different species are found in DD; however, the species Treponema phagedenis is uniformly found in copious quantities and deep within the skin layers of the active, ulcerative stages of disease. The pathogenic mechanisms these bacteria use to persist in the skin and the precise role they play in the pathology of DD are widely unknown. To explore the pathogenesis and virulence of Treponema phagedenis, newly isolated strains of this species were investigated in a subcutaneous murine abscess model. In the first trial, a dosage study was conducted to compare the pathogenicity of different strains across three different treponemes per inoculum (TPI) doses based on abscess volumes. In the second trial, the expression levels of 11 putative virulence genes were obtained to gain insight into their involvement in pathogenesis. During the RT-qPCR analysis, it was determined that genes encoding for two metal-ion import lipoproteins and two adherence genes were found highly upregulated during infection. Conversely, two genes involved in motility and chemotaxis were found to not be significantly upregulated or utilized during infection. These results were supported by gene expression data from natural M2 lesions of dairy cattle. This gene expression analysis could highlight the preference in strategy for T. phagedenis to persist and adhere in the host rather than engage in motility and disseminate.
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Affiliation(s)
- Colton Scott
- Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Angelica P Dias
- Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jeroen De Buck
- Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
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Liu Y, Li Y, Peng Y, Feng L, Wang W, Li C, Zhang Y, Wang R, Li C, Ma C, Yang C. Identification and Characterization of Bacterial Alliinase: Resource and Substrate Stereospecificity. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:13228-13239. [PMID: 38810088 DOI: 10.1021/acs.jafc.4c02404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
Limited alliinase resources cause difficulties in the biosynthesis of thiosulfinates (e.g., allicin), restricting their applications in the agricultural and food industries. To effectively biosynthesize thiosulfinates, this study aimed to excavate bacterial alliinase resources and elucidate their catalytic properties. Two bacterial cystathionine β-lyases (MetCs) possessing high alliinase activity (>60 U mg -1) toward L-(-)-alliin were identified from Allium sativum rhizosphere isolates. Metagenomic exploration revealed that cystathionine β-lyase from Bacillus cereus (BcPatB) possessed high activity toward both L-(±)-alliin and L-(+)-alliin (208.6 and 225.1 U mg -1), respectively. Although these enzymes all preferred l-cysteine S-conjugate sulfoxides as substrates, BcPatB had a closer phylogenetic relationship with Allium alliinases and shared several similar features with A. sativum alliinase. Interestingly, the Trp30Ile31Ala32Asp33 Met34 motif in a cuspate loop of BcPatB, especially sites 31 and 32 at the top of the motif, was modeled to locate near the sulfoxide of L-(+)-alliin and is important for substrate stereospecificity. Moreover, the stereoselectivity and activity of mutants I31V and A32G were higher toward L-(+)-alliin than those of mutant I31L/D33E toward L-(-)-alliin. Using bacterial alliinases and chemically synthesized substrates, we obtained thiosulfinates with high antimicrobial and antinematode activities that could provide insights into the protection of crops and food.
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Affiliation(s)
- Yuanxiang Liu
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, P. R. China
| | - Yaru Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, P. R. China
| | - Yishu Peng
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, P. R. China
| | - Luhua Feng
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, P. R. China
| | - Wei Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, P. R. China
| | - Chongzhou Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, P. R. China
| | - Ye Zhang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, P. R. China
| | - Ruimin Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, P. R. China
| | - Chunfang Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, P. R. China
| | - Cuiqing Ma
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, P. R. China
| | - Chunyu Yang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao 266237, P. R. China
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Andreolli M, Lampis S, Tosi L, Marano V, Zapparoli G. Fungicide sensitivity of grapevine bacteria with plant growth-promoting traits and antagonistic activity as non-target microorganisms. World J Microbiol Biotechnol 2023; 39:121. [PMID: 36929028 PMCID: PMC10020324 DOI: 10.1007/s11274-023-03569-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 03/07/2023] [Indexed: 03/18/2023]
Abstract
This study evaluates the capacity of commercial formulations of synthetic fungicides to inhibit grapevine bacterial growth when sprayed on vineyards to control diseases, such as downy mildew, powdery mildew and secondary rots. Fungicide sensitivity plate assays were carried out on bacteria isolated from vineyards that were also identified and characterized for their plant growth-promoting (PGP) traits and antifungal activity. The high taxonomic variability of bacteria screened with different chemical classes of fungicides is one new finding of this study. Seven out of 11 fungicides were able to inhibit the growth of bacteria at a concentration corresponding to the maximum dose allowed by law in spray treatments of vineyards. Bacterial sensitivity to each fungicide varied greatly. Many sensitive isolates displayed PGP traits and/or antagonistic activity. This study shows the potential impact of fungicidal treatments on grapevine bacterial microbiota. The involvement of bacteria beneficial to the growth and health of plants underlines the importance of this investigation. Our data reveal that the control of a certain disease may be possible using fungicides that have no or low impact on natural non-target microbiota. Understanding the action mechanisms of the active ingredients in these products is a priority for the development of new eco-friendly pesticides.
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Affiliation(s)
- Marco Andreolli
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, Verona, 37134, Italy
| | - Silvia Lampis
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, Verona, 37134, Italy
| | - Lorenzo Tosi
- AGREA Centro Studi, San Giovanni Lupatoto, Italy
| | - Viviana Marano
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, Verona, 37134, Italy
| | - Giacomo Zapparoli
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, Verona, 37134, Italy.
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Yu S, Kang J, Chung EH, Lee Y. Disruption of the metC Gene Affects Methionine Biosynthesis in Pectobacterium carotovorum subsp. carotovorum Pcc21 and Reduces Soft-Rot Disease. THE PLANT PATHOLOGY JOURNAL 2023; 39:62-74. [PMID: 36760050 PMCID: PMC9929172 DOI: 10.5423/ppj.oa.09.2022.0135] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/28/2022] [Accepted: 11/28/2022] [Indexed: 06/18/2023]
Abstract
Plant pathogenic Pectobacterium species cause severe soft rot/blackleg diseases in many economically important crops worldwide. Pectobacterium utilizes plant cell wall degrading enzymes (PCWDEs) as the main virulence determinants for its pathogenicity. In this study, we screened a random mutant, M29 is a transposon insertion mutation in the metC gene encoding cystathionine β-lyase that catalyzes cystathionine to homocysteine at the penultimate step in methionine biosynthesis. M29 became a methionine auxotroph and resulted in growth defects in methionine-limited conditions. Impaired growth was restored with exogenous methionine or homocysteine rather than cystathionine. The mutant exhibited reduced soft rot symptoms in Chinese cabbages and potato tubers, maintaining activities of PCWDEs and swimming motility. The mutant was unable to proliferate in both Chinese cabbages and potato tubers. The reduced virulence was partially restored by a complemented strain or 100 µM of methionine, whereas it was fully restored by the extremely high concentration (1 mM). Our transcriptomic analysis showed that genes involved in methionine biosynthesis or transporter were downregulated in the mutant. Our results demonstrate that MetC is important for methionine biosynthesis and transporter and influences its virulence through Pcc21 multiplication in plant hosts.
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Affiliation(s)
- Seonmi Yu
- Department of Food Science and Biotechnology, CHA University, Pocheon 11160,
Korea
| | - Jihee Kang
- Department of Food Science and Biotechnology, CHA University, Pocheon 11160,
Korea
| | - Eui-Hwan Chung
- Department of Plant Biotechnology, Korea University, Seoul 02841,
Korea
| | - Yunho Lee
- Department of Food Science and Biotechnology, CHA University, Pocheon 11160,
Korea
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Chen YY, Huang CT, Li SW, Pan YJ, Lin TL, Huang YY, Li TH, Yang YC, Gong YN, Hsieh YC. Bacterial factors required for Streptococcus pneumoniae coinfection with influenza A virus. J Biomed Sci 2021; 28:60. [PMID: 34452635 PMCID: PMC8395381 DOI: 10.1186/s12929-021-00756-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 08/17/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Streptococcus pneumoniae is a common cause of post-influenza secondary bacterial infection, which results in excessive morbidity and mortality. Although 13-valent pneumococcal conjugate vaccine (PCV13) vaccination programs have decreased the incidence of pneumococcal pneumonia, PCV13 failed to prevent serotype 3 pneumococcal disease as effectively as other vaccine serotypes. We aimed to investigate the mechanisms underlying the co-pathogenesis of influenza virus and serotype 3 pneumococci. METHODS We carried out a genome-wide screening of a serotype 3 S. pneumoniae transposon insertion mutant library in a mouse model of coinfection with influenza A virus (IAV) to identify the bacterial factors required for this synergism. RESULTS Direct, high-throughput sequencing of transposon insertion sites identified 24 genes required for both coinfection and bacterial infection alone. Targeted deletion of the putative aminotransferase (PA) gene decreased bacterial growth, which was restored by supplementation with methionine. The bacterial burden in a coinfection with the PA gene deletion mutant and IAV in the lung was lower than that in a coinfection with wild-type pneumococcus and IAV, but was significantly higher than that in an infection with the PA gene deletion mutant alone. These data suggest that IAV infection alters host metabolism to benefit pneumococcal fitness and confer higher susceptibility to pneumococcal infection. We further demonstrated that bacterial growth was increased by supplementation with methionine or IAV-infected mouse lung homogenates. CONCLUSIONS The data indicates that modulation of host metabolism during IAV infection may serve as a potential therapeutic intervention against secondary bacterial infections caused by serotype 3 pneumococci during IAV outbreaks in the future.
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Affiliation(s)
- Yi-Yin Chen
- Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Ching-Tai Huang
- Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital, Taipei, Taoyuan, Taiwan
| | - Shiao-Wen Li
- Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan
| | - Yi-Jiun Pan
- Department of Microbiology and Immunology, School of Medicine, College of Medicine, China Medical University, Taichung, Taiwan
| | - Tzu-Lung Lin
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Ya-Yu Huang
- Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Ting-Hsuan Li
- Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Yu-Ching Yang
- Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Yu-Nong Gong
- Research Center for Emerging Viral Infections, Chang Gung University, Taoyuan, Taiwan
- Department of Laboratory Medicine, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Yu-Chia Hsieh
- Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
- Department of Pediatrics, Linkou Chang Gung Memorial Hospital, No. 5, Fuxing Street, Guishan District, Taoyuan City, 333, Taiwan.
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Ohtsuka H, Shimasaki T, Aiba H. Response to sulfur in Schizosaccharomyces pombe. FEMS Yeast Res 2021; 21:6324000. [PMID: 34279603 PMCID: PMC8310684 DOI: 10.1093/femsyr/foab041] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 07/13/2021] [Indexed: 12/13/2022] Open
Abstract
Sulfur is an essential component of various biologically important molecules, including methionine, cysteine and glutathione, and it is also involved in coping with oxidative and heavy metal stress. Studies using model organisms, including budding yeast (Saccharomyces cerevisiae) and fission yeast (Schizosaccharomyces pombe), have contributed not only to understanding various cellular processes but also to understanding the utilization and response mechanisms of each nutrient, including sulfur. Although fission yeast can use sulfate as a sulfur source, its sulfur metabolism pathway is slightly different from that of budding yeast because it does not have a trans-sulfuration pathway. In recent years, it has been found that sulfur starvation causes various cellular responses in S. pombe, including sporulation, cell cycle arrest at G2, chronological lifespan extension, autophagy induction and reduced translation. This MiniReview identifies two sulfate transporters in S. pombe, Sul1 (encoded by SPBC3H7.02) and Sul2 (encoded by SPAC869.05c), and summarizes the metabolic pathways of sulfur assimilation and cellular response to sulfur starvation. Understanding these responses, including metabolism and adaptation, will contribute to a better understanding of the various stress and nutrient starvation responses and chronological lifespan regulation caused by sulfur starvation.
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Affiliation(s)
- Hokuto Ohtsuka
- Laboratory of Molecular Microbiology, Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan
| | - Takafumi Shimasaki
- Laboratory of Molecular Microbiology, Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan
| | - Hirofumi Aiba
- Laboratory of Molecular Microbiology, Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan
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Characterisation of Listeria monocytogenes food-associated isolates to assess environmental fitness and virulence potential. Int J Food Microbiol 2021; 350:109247. [PMID: 34023680 DOI: 10.1016/j.ijfoodmicro.2021.109247] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 05/03/2021] [Accepted: 05/13/2021] [Indexed: 11/22/2022]
Abstract
The ability of Listeria monocytogenes isolates to survive within the food production environment (FPE), as well as virulence, varies greatly between strains. There are specific genetic determinants that have been identified which can strongly influence a strains ability to survive in the FPE and/or within human hosts. In this study, we assessed the FPE fitness and virulence potential, including efficacy of selected hygiene or treatment intervention, against 52 L. monocytogenes strains isolated from various food and food environment sources. Phenotypic tests were performed to determine the minimum inhibitory concentration of cadmium chloride and benzalkonium chloride and the sensitivities to five clinically relevant antibiotics. A genomic analysis was also performed to identify resistance genes correlating to the observed phenotypic resistance profiles, along with genetic determinants of interest which may elude to the FPE fitness and virulence potential. A transposon element containing a novel cadmium resistance gene, cadA7, a Tn916 variant insert in the hypervariable Listeria genomic island 1 region and an LGI2 variant were identified. Resistance to cadmium and disinfectants was prevalent among isolates in this study, although no resistance to clinically important antimicrobials was observed. Potential hypervirulent strains containing full length inlA, LIPI-1 and LIPI-3 were also identified in this study. Cumulatively, the results of this study show a vast array of FPE survival and pathogenicity potential among food production-associated isolates, which may be of concern for food processing operators and clinicians regarding L. monocytogenes strains colonising and persisting within the FPE, and subsequently contaminating food products then causing disease in at risk population groups.
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Pei X, Liu J, Liu M, Zhou H, Wang X, Fan H. Quantitative proteomics revealed modulation of macrophages by MetQ gene of Streptococcus suis serotype 2. AMB Express 2020; 10:195. [PMID: 33125582 PMCID: PMC7599288 DOI: 10.1186/s13568-020-01131-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Accepted: 10/18/2020] [Indexed: 11/10/2022] Open
Abstract
Streptococcus suis serotype 2 (SS2) is a serious zoonotic pathogen; it can lead to symptoms of streptococcal toxic shock syndrome (STSS) in humans and sepsis in pigs, and poses a great threat to public health. The SS2 MetQ gene deletion strain has attenuated antiphagocytosis, although the mechanism of antiphagocytosis and pathogenesis of MetQ in SS2 has remained unclear. In this study, stable isotope labeling by amino acids in cell culture (SILAC) based liquid chromatography–mass spectrometry (LC–MS) and subsequent bioinformatics analysis was used to determine differentially expressed proteins of RAW264.7 cells infected with △MetQ and ZY05719. Proteomic results were verified by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting for selected proteins. Further research was focused mainly on immune system processes related to downregulated proteins, such as Src and Ccl9, and actin cytoskeleton and endocytosis related upregulated proteins, like Pstpip1 and Ppp1r9b. The proteomic results in this study shed light on the mechanism of antiphagocytosis and innate immunity of macrophages infected with △MetQ and ZY05719, which might provide novel targets to prevent or control the infection of SS2.
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MetA (Rv3341) from Mycobacterium tuberculosis H37Rv strain exhibits substrate dependent dual role of transferase and hydrolase activity. Biochimie 2020; 179:113-126. [PMID: 32976971 DOI: 10.1016/j.biochi.2020.09.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 08/10/2020] [Accepted: 09/13/2020] [Indexed: 02/08/2023]
Abstract
The metA (Rv3341) gene from Mycobacterium tuberculosis H37Rv strain encodes a homoserine-acetyltransferase (HAT) enzyme, also called MetA. This enzyme plays a key role in the biosynthetic pathway of methionine and is a potential target for the development of antimicrobial drugs. Purified MetA showed 40 kDa molecular mass on SDS-PAGE. Manual docking was performed with substrates acetyl-CoA, l-homoserine, and p-nitrophenylacetate using crystal structure coordinates of MetA (PDB ID 6PUX) from M. tuberculosis. Multiple sequence alignment indicated that catalytic triad residues Ser157, Asp320, His350 were conserved across species in acetyltransferases, esterases, and hydrolases. As a conserved pentapeptide, GXSMG belongs to α/β hydrolase superfamily and it shares similarity with esterases and hydrolases from different sources. Hydrolase activity of MetA was tested using (PNPA), N-acetylglycine, N-acetylmethionine and Phe-Gly as substrate. LC-MS confirmed that MetA possessed HAT activity, but no homoserine-succinyltransferase (HST) and serine-acetyltransferase (SAT) activities. Replacing acetyl-CoA with PNPA as acetyl group donor showed a drastic reduction in transferase activity, arising due to the interaction of R227 of the enzyme with PNPA. This could prevent the binding of the second substrate in the right orientation and results in the preferential transfer of the acetyl group to water, thus exhibiting hydrolase rather than transferase activity. In this paper, we report that MetA has both transferase and hydrolase activity depending on the correct orientation of the second substrate and the availability of the amino acids involved in enzyme-substrate interaction.
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Shahbaaz M, Potemkin V, Bisetty K, Hassan MI, Hussien MA. Classification and functional analyses of putative virulence factors of Mycobacterium tuberculosis: A combined sequence and structure based study. Comput Biol Chem 2020; 87:107270. [PMID: 32438116 DOI: 10.1016/j.compbiolchem.2020.107270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 04/16/2020] [Accepted: 04/26/2020] [Indexed: 11/17/2022]
Abstract
The emergence of the drug-resistant mechanisms in Mycobacterium tuberculosis poses the biggest challenges to the current therapeutic measures, which necessitates the identification of new drug targets. The Hypothetical Proteins (HPs), a class of functionally uncharacterized proteins, may provide a new class of undiscovered therapeutic targets. The genome of M. tuberculosis contains 1000 HPs with their sequences were analyzed using a variety of bioinformatics tools and the functional annotations were performed. The functions of 662 HPs were successfully predicted and further classified 483 HPs as enzymes, 141 HPs were predicted to be involved in the diverse cellular mechanisms and 38 HPs may function as transporters and carriers proteins. Furthermore, 28 HPs were predicted to be virulent in nature. Amongst them, the HP P95201, HP P9WM79, HP I6WZ30, HP I6 × 9T8, HP P9WKP3, and HP P9WK89 showed the highest virulence scores. Therefore, these proteins were subjected to extensive structure analyses and dynamics of their conformations were investigated using the principles of molecular dynamics simulations, each for a 150 ns time scale. This study provides a deeper understanding of the undiscovered drug targets and the generated outputs will facilitate the process of drug design and discovery against the infection of M. tuberculosis.
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Affiliation(s)
- Mohd Shahbaaz
- South African Medical Research Council Bioinformatics Unit, South African National Bioinformatics Institute (SANBI), University of the Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa; Laboratory of Computational Modeling of Drugs, South Ural State University, 76 Lenin prospekt, 454080 Chelyabinsk, Russia
| | - Vladimir Potemkin
- Laboratory of Computational Modeling of Drugs, South Ural State University, 76 Lenin prospekt, 454080 Chelyabinsk, Russia
| | - Krishna Bisetty
- Department of Chemistry, Durban University of Technology, Durban, 4000, South Africa
| | - Md Imtaiyaz Hassan
- Center for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Mostafa A Hussien
- Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203 Jeddah 21589, Saudi Arabia; Department of Chemistry, Faculty of Science, Port Said University, Port Said, 42521, Egypt
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Chen Y, Li B, Xu X, Zhang Z, Tian S. The pH-responsive PacC transcription factor plays pivotal roles in virulence and patulin biosynthesis in Penicillium expansum. Environ Microbiol 2019; 20:4063-4078. [PMID: 30370586 DOI: 10.1111/1462-2920.14453] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 10/16/2018] [Indexed: 01/24/2023]
Abstract
The PacC (loss or reduction in phosphatase activity at acid but not at alkaline pH [Pac]) transcription factor regulates environmental adaptation, secondary metabolism and virulence in many fungal pathogens. Here, we report the functions of PacC in Penicillium expansum, a postharvest pathogenic fungus in horticultural crops, and ascertain that the gene expression and proteolytic processing of PePacC are strictly pH-dependent. Loss of PePacC resulted in an obvious decrease in growth and conidiation of P. expansum cultured in both acidic and alkaline conditions. The ΔPePacC mutant lost the ability of patulin production at pH values above 6.0 because expressions of all the genes in patulin cluster were significantly down-regulated. Additionally, virulence of the ΔPePacC mutant was obviously reduced in pear and apple fruits. Proteome analysis revealed that PePacC could function as an activator or repressor for different target proteins, including calreticulin (PeCRT) and sulfate adenylyltransferase (PeSAT), which were further proved to be involved in virulence of P. expansum. Our results demonstrate important roles for PePacC in patulin biosynthesis via limiting expressions of the genes in the cluster, and in pathogenesis via mediating a known virulence factor glucose oxidase (PeGOD) and new virulence factors, such as PeCRT and PeSAT.
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Affiliation(s)
- Yong Chen
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Boqiang Li
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Xiaodi Xu
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhanquan Zhang
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Shiping Tian
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.,University of Chinese Academy of Sciences, Beijing, 100049, China.,Biotechnology and Bioresources Utilization, Ministry of Education, Dalian, 116600, China
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Methionine Limitation Impairs Pathogen Expansion and Biofilm Formation Capacity. Appl Environ Microbiol 2019; 85:AEM.00177-19. [PMID: 30824455 DOI: 10.1128/aem.00177-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 02/23/2019] [Indexed: 02/01/2023] Open
Abstract
Multidrug-resistant bacterial pathogens are becoming increasingly prevalent, and novel strategies to treat bacterial infections caused by these organisms are desperately needed. Bacterial central metabolism is crucial for catabolic processes and provides precursors for anabolic pathways, such as the biosynthesis of essential biomolecules like amino acids or vitamins. However, most essential pathways are not regarded as good targets for antibiotic therapy since their products might be acquired from the environment. This issue raises doubts about the essentiality of such targets during infection. A putative target in bacterial anabolism is the methionine biosynthesis pathway. In contrast to humans, almost all bacteria carry methionine biosynthesis pathways which have often been suggested as putative targets for novel anti-infectives. While the growth of methionine auxotrophic strains can be stimulated by exogenous methionine, the extracellular concentrations required by most bacterial species are unknown. Furthermore, several phenotypic characteristics of methionine auxotrophs are only partly reversed by exogenous methionine. We investigated methionine auxotrophic mutants of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli (all differing in methionine biosynthesis enzymes) and found that each needed concentrations of exogenous methionine far exceeding that reported for human serum (∼30 µM). Accordingly, these methionine auxotrophs showed a reduced ability to proliferate in human serum. Additionally, S. aureus and P. aeruginosa methionine auxotrophs were significantly impaired in their ability to form and maintain biofilms. Altogether, our data show intrinsic defects of methionine auxotrophs. This result suggests that the pathway should be considered for further studies validating the therapeutic potential of inhibitors.IMPORTANCE New antibiotics that attack novel targets are needed to circumvent widespread resistance to conventional drugs. Bacterial anabolic pathways, such as the enzymes for biosynthesis of the essential amino acid methionine, have been proposed as potential targets. However, the eligibility of enzymes in these pathways as drug targets is unclear because metabolites might be acquired from the environment to overcome inhibition. We investigated the nutritional needs of methionine auxotrophs of the pathogens Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli We found that each auxotrophic strain retained a growth disadvantage at methionine concentrations mimicking those available in vivo and showed that biofilm biomass was strongly influenced by endogenous methionine biosynthesis. Our experiments suggest that inhibition of the methionine biosynthesis pathway has deleterious effects even in the presence of external methionine. Therefore, additional efforts to validate the effects of methionine biosynthesis inhibitors in vivo are warranted.
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Motility, Biofilm Formation and Antimicrobial Efflux of Sessile and Planktonic Cells of Achromobacter xylosoxidans. Pathogens 2019; 8:pathogens8010014. [PMID: 30691200 PMCID: PMC6471707 DOI: 10.3390/pathogens8010014] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 01/18/2019] [Accepted: 01/24/2019] [Indexed: 11/17/2022] Open
Abstract
Achromobacter xylosoxidans is an innately multidrug-resistant bacterium capable of forming biofilms in the respiratory tract of cystic fibrosis (CF) patients. During the transition from the planktonic stage to biofilm growth, bacteria undergo a transcriptionally regulated differentiation. An isolate of A. xylosoxidans cultured from the sputum of a CF patient was separated into sessile and planktonic stages in vitro, and the transcriptomes were compared. The selected genes of interest were subsequently inactivated, and flagellar motility was found to be decisive for biofilm formation in vitro. The spectrum of a new resistance-nodulation-cell division (RND)-type multidrug efflux pump (AxyEF-OprN) was characterized by inactivation of the membrane fusion protein. AxyEF-OprN is capable of extruding some fluoroquinolones (levofloxacin and ciprofloxacin), tetracyclines (doxycycline and tigecycline) and carpabenems (ertapenem and imipenem), which are classes of antimicrobials that are widely used for treatment of CF pulmonary infections.
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14
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Gazi MA, Mahmud S, Fahim SM, Kibria MG, Palit P, Islam MR, Rashid H, Das S, Mahfuz M, Ahmeed T. Functional Prediction of Hypothetical Proteins from Shigella flexneri and Validation of the Predicted Models by Using ROC Curve Analysis. Genomics Inform 2018; 16:e26. [PMID: 30602087 PMCID: PMC6440662 DOI: 10.5808/gi.2018.16.4.e26] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 09/16/2018] [Indexed: 01/04/2023] Open
Abstract
Shigella spp. constitutes some of the key pathogens responsible for the global burden of diarrhoeal disease. With over 164 million reported cases per annum, shigellosis accounts for 1.1 million deaths each year. Majority of these cases occur among the children of the developing nations and the emergence of multi-drug resistance Shigella strains in clinical isolates demands the development of better/new drugs against this pathogen. The genome of Shigella flexneri was extensively analyzed and found 4,362 proteins among which the functions of 674 proteins, termed as hypothetical proteins (HPs) had not been previously elucidated. Amino acid sequences of all these 674 HPs were studied and the functions of a total of 39 HPs have been assigned with high level of confidence. Here we have utilized a combination of the latest versions of databases to assign the precise function of HPs for which no experimental information is available. These HPs were found to belong to various classes of proteins such as enzymes, binding proteins, signal transducers, lipoprotein, transporters, virulence and other proteins. Evaluation of the performance of the various computational tools conducted using receiver operating characteristic curve analysis and a resoundingly high average accuracy of 93.6% were obtained. Our comprehensive analysis will help to gain greater understanding for the development of many novel potential therapeutic interventions to defeat Shigella infection.
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Affiliation(s)
- Md Amran Gazi
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Sultan Mahmud
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Shah Mohammad Fahim
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Mohammad Golam Kibria
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Parag Palit
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Md Rezaul Islam
- International Max Planck Research School, Grisebachstraße 5, 37077 Göttingen, Germany
| | - Humaira Rashid
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Subhasish Das
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Mustafa Mahfuz
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
| | - Tahmeed Ahmeed
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka 1212, Bangladesh
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15
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Husna AU, Wang N, Cobbold SA, Newton HJ, Hocking DM, Wilksch JJ, Scott TA, Davies MR, Hinton JC, Tree JJ, Lithgow T, McConville MJ, Strugnell RA. Methionine biosynthesis and transport are functionally redundant for the growth and virulence of Salmonella Typhimurium. J Biol Chem 2018; 293:9506-9519. [PMID: 29720401 PMCID: PMC6005444 DOI: 10.1074/jbc.ra118.002592] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/28/2018] [Indexed: 11/06/2022] Open
Abstract
Methionine (Met) is an amino acid essential for many important cellular and biosynthetic functions, including the initiation of protein synthesis and S-adenosylmethionine–mediated methylation of proteins, RNA, and DNA. The de novo biosynthetic pathway of Met is well conserved across prokaryotes but absent from vertebrates, making it a plausible antimicrobial target. Using a systematic approach, we examined the essentiality of de novo methionine biosynthesis in Salmonella enterica serovar Typhimurium, a bacterial pathogen causing significant gastrointestinal and systemic diseases in humans and agricultural animals. Our data demonstrate that Met biosynthesis is essential for S. Typhimurium to grow in synthetic medium and within cultured epithelial cells where Met is depleted in the environment. During systemic infection of mice, the virulence of S. Typhimurium was not affected when either de novo Met biosynthesis or high-affinity Met transport was disrupted alone, but combined disruption in both led to severe in vivo growth attenuation, demonstrating a functional redundancy between de novo biosynthesis and acquisition as a mechanism of sourcing Met to support growth and virulence for S. Typhimurium during infection. In addition, our LC-MS analysis revealed global changes in the metabolome of S. Typhimurium mutants lacking Met biosynthesis and also uncovered unexpected interactions between Met and peptidoglycan biosynthesis. Together, this study highlights the complexity of the interactions between a single amino acid, Met, and other bacterial processes leading to virulence in the host and indicates that disrupting the de novo biosynthetic pathway alone is likely to be ineffective as an antimicrobial therapy against S. Typhimurium.
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Affiliation(s)
- Asma Ul Husna
- From the Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, Victoria 3000, Australia
| | - Nancy Wang
- From the Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, Victoria 3000, Australia,
| | - Simon A Cobbold
- the Department of Biochemistry and Molecular Biology, University of Melbourne at the Bio21 Institute, Parkville, Victoria 3052, Australia
| | - Hayley J Newton
- From the Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, Victoria 3000, Australia
| | - Dianna M Hocking
- From the Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, Victoria 3000, Australia
| | - Jonathan J Wilksch
- From the Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, Victoria 3000, Australia
| | - Timothy A Scott
- From the Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, Victoria 3000, Australia
| | - Mark R Davies
- From the Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, Victoria 3000, Australia
| | - Jay C Hinton
- the Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Jai J Tree
- From the Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, Victoria 3000, Australia.,the School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia, and
| | - Trevor Lithgow
- the Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Malcolm J McConville
- the Department of Biochemistry and Molecular Biology, University of Melbourne at the Bio21 Institute, Parkville, Victoria 3052, Australia
| | - Richard A Strugnell
- From the Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, Victoria 3000, Australia,
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16
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Muller C, Massier S, Le Breton Y, Rincé A. The role of the CroR response regulator in resistance of Enterococcus faecalis to D-cycloserine is defined using an inducible receiver domain. Mol Microbiol 2017; 107:416-427. [PMID: 29205552 DOI: 10.1111/mmi.13891] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/28/2017] [Accepted: 12/01/2017] [Indexed: 11/28/2022]
Abstract
Enterococcus faecalis is an opportunistic multidrug-resistant human pathogen causing severe nosocomial infections. Previous investigations revealed that the CroRS two-component regulatory pathway likely displays a pleiotropic role in E. faecalis, involved in virulence, macrophage survival, oxidative stress response as well as antibiotic resistance. Therefore, CroRS represents an attractive potential new target for antibiotherapy. In this report, we further explored CroRS cellular functions by characterizing the CroR regulon: the 'domain swapping' method was applied and a CroR chimera protein was generated by fusing the receiver domain from NisR to the output domain from CroR. After demonstrating that the chimera CroR complements a croR gene deletion in E. faecalis (stress response, virulence), we conducted a global gene expression analysis using RNA-Seq and identified 50 potential CroR targets involved in multiple cellular functions such as cell envelope homeostasis, substrate transport, cell metabolism, gene expression regulation, stress response, virulence and antibiotic resistance. For validation, CroR direct binding to several candidate targets was demonstrated by EMSA. Further, this work identified alr, the gene encoding the alanine racemase enzyme involved in E. faecalis resistance to D-cycloserine, a promising antimicrobial drug to treat enterococcal infections, as a member of the CroR regulon.
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Affiliation(s)
- Cécile Muller
- Normandie Univ, UNICAEN, U2RM - Unité de Recherche Risques Microbiens, Caen, France
| | - Sébastien Massier
- Normandie Univ, UNICAEN, U2RM - Unité de Recherche Risques Microbiens, Caen, France
| | - Yoann Le Breton
- Normandie Univ, UNICAEN, U2RM - Unité de Recherche Risques Microbiens, Caen, France
| | - Alain Rincé
- Normandie Univ, UNICAEN, U2RM - Unité de Recherche Risques Microbiens, Caen, France
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17
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Descamps T, De Smet L, De Vos P, de Graaf D. Unbiased random mutagenesis contributes to a better understanding of the virulent behaviour ofPaenibacillus larvae. J Appl Microbiol 2017; 124:28-41. [DOI: 10.1111/jam.13611] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 08/09/2017] [Accepted: 09/28/2017] [Indexed: 01/12/2023]
Affiliation(s)
- T. Descamps
- Laboratory of Molecular Entomology and Bee Pathology; Faculty of Sciences; Ghent University; Ghent Belgium
| | - L. De Smet
- Laboratory of Molecular Entomology and Bee Pathology; Faculty of Sciences; Ghent University; Ghent Belgium
| | - P. De Vos
- Laboratory of Microbiology; Faculty of Sciences; Ghent University; Ghent Belgium
| | - D.C. de Graaf
- Laboratory of Molecular Entomology and Bee Pathology; Faculty of Sciences; Ghent University; Ghent Belgium
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18
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iTRAQ-based quantitative proteomic analysis reveals potential virulence factors of Erysipelothrix rhusiopathiae. J Proteomics 2017; 160:28-37. [DOI: 10.1016/j.jprot.2017.03.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 03/01/2017] [Accepted: 03/04/2017] [Indexed: 12/28/2022]
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19
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MetQ of Neisseria gonorrhoeae Is a Surface-Expressed Antigen That Elicits Bactericidal and Functional Blocking Antibodies. Infect Immun 2017; 85:IAI.00898-16. [PMID: 27895130 PMCID: PMC5278169 DOI: 10.1128/iai.00898-16] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 11/19/2016] [Indexed: 01/30/2023] Open
Abstract
Neisseria gonorrhoeae, the causative agent of the sexually transmitted infection (STI) gonorrhea, is a growing public health threat for which a vaccine is urgently needed. We characterized the functional role of the gonococcal MetQ protein, which is the methionine binding component of an ABC transporter system, and assessed its potential as a candidate antigen for inclusion in a gonococcal vaccine. MetQ has been found to be highly conserved in all strains investigated to date, it is localized on the bacterial surface, and it binds l-methionine with a high affinity. MetQ is also involved in gonococcal adherence to cervical epithelial cells. Mutants lacking MetQ have impaired survival in human monocytes, macrophages, and serum. Furthermore, antibodies raised against MetQ are bactericidal and are able to block gonococcal adherence to epithelial cells. These data suggest that MetQ elicits both bactericidal and functional blocking antibodies and is a valid candidate antigen for additional investigation and possible inclusion in a vaccine for prevention of gonorrhea.
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20
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Afzal M, Manzoor I, Kuipers OP, Shafeeq S. Cysteine-Mediated Gene Expression and Characterization of the CmbR Regulon in Streptococcus pneumoniae. Front Microbiol 2016; 7:1929. [PMID: 27990139 PMCID: PMC5131005 DOI: 10.3389/fmicb.2016.01929] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 11/16/2016] [Indexed: 11/13/2022] Open
Abstract
In this study, we investigated the transcriptomic response of Streptococcus pneumoniae D39 to cysteine. Transcriptome comparison of the D39 wild-type grown at a restricted concentration of cysteine (0.03 mM) to one grown at a high concentration of cysteine (50 mM) in chemically-defined medium (CDM) revealed elevated expression of various genes/operons, i.e., spd-0150, metQ, spd-0431, metEF, gshT, spd-0618, fhs, tcyB, metB-csd, metA, spd-1898, yvdE, and cysK, likely to be involved in the transport and utilization of cysteine and/or methionine. Microarray-based data were further confirmed by quantitative RT-PCR. Promoter lacZ-fusion studies and quantitative RT-PCR data showed that the transcriptional regulator CmbR acts as a transcriptional repressor of spd-0150, metEF, gshT, spd-0618, tcyB, metA, and yvdE, putatively involved in cysteine uptake and utilization. The operator site of CmbR in the promoter regions of CmbR-regulated genes is predicted and confirmed by mutating or deleting CmbR operator sites from the promoter regions of these genes.
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Affiliation(s)
- Muhammad Afzal
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of GroningenGroningen, Netherlands; Department of Bioinformatics and Biotechnology, Government College UniversityFaisalabad, Pakistan
| | - Irfan Manzoor
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of GroningenGroningen, Netherlands; Department of Bioinformatics and Biotechnology, Government College UniversityFaisalabad, Pakistan
| | - Oscar P Kuipers
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen Groningen, Netherlands
| | - Sulman Shafeeq
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet Stockholm, Sweden
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21
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Afzal M, Shafeeq S, Kuipers OP. Methionine-mediated gene expression and characterization of the CmhR regulon in Streptococcus pneumoniae. Microb Genom 2016; 2:e000091. [PMID: 28348831 PMCID: PMC5359408 DOI: 10.1099/mgen.0.000091] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 09/25/2016] [Indexed: 11/18/2022] Open
Abstract
This study investigated the transcriptomic response of Streptococcus pneumoniae D39 to methionine. Transcriptome comparison of the S. pneumoniae D39 wild-type grown in chemically defined medium with 0–10 mM methionine revealed the elevated expression of various genes/operons involved in methionine synthesis and transport (fhs, folD, gshT, metA, metB-csd, metEF, metQ, tcyB, spd-0150, spd-0431 and spd-0618). Furthermore, β-galactosidase assays and quantitative RT-PCR studies demonstrated that the transcriptional regulator, CmhR (SPD-0588), acts as a transcriptional activator of the fhs, folD, metB-csd, metEF, metQ and spd-0431 genes. A putative regulatory site of CmhR was identified in the promoter region of CmhR-regulated genes and this CmhR site was further confirmed by promoter mutational experiments.
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Affiliation(s)
- Muhammad Afzal
- 1Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands.,2Department of Bioinformatics and Biotechnology, G C University, Faisalabad, Pakistan
| | - Sulman Shafeeq
- 3Department of Microbiology, Tumor and Cell Biology, , Karolinska Institutet, Nobels väg 16, Stockholm, SE-171 77, Sweden
| | - Oscar P Kuipers
- 1Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
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22
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The In Vitro Redundant Enzymes PurN and PurT Are Both Essential for Systemic Infection of Mice in Salmonella enterica Serovar Typhimurium. Infect Immun 2016; 84:2076-2085. [PMID: 27113361 DOI: 10.1128/iai.00182-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 04/21/2016] [Indexed: 11/20/2022] Open
Abstract
Metabolic enzymes show a high degree of redundancy, and for that reason they are generally ignored in searches for novel targets for anti-infective substances. The enzymes PurN and PurT are redundant in vitro in Salmonella enterica serovar Typhimurium, in which they perform the third step of purine synthesis. Surprisingly, the results of the current study demonstrated that single-gene deletions of each of the genes encoding these enzymes caused attenuation (competitive infection indexes [CI] of <0.03) in mouse infections. While the ΔpurT mutant multiplied as fast as the wild-type strain in cultured J774A.1 macrophages, net multiplication of the ΔpurN mutant was reduced approximately 50% in 20 h. The attenuation of the ΔpurT mutant was abolished by simultaneous removal of the enzyme PurU, responsible for the formation of formate, indicating that the attenuation was related to formate accumulation or wasteful consumption of formyl tetrahydrofolate by PurU. In the process of further characterization, we disclosed that the glycine cleavage system (GCV) was the most important for formation of C1 units in vivo (CI = 0.03 ± 0.03). In contrast, GlyA was the only important enzyme for the formation of C1 units in vitro The results with the ΔgcvT mutant further revealed that formation of serine by SerA and further conversion of serine into C1 units and glycine by GlyA were not sufficient to ensure C1 formation in S Typhimurium in vivo The results of the present study call for reinvestigations of the concept of metabolic redundancy in S Typhimurium in vivo.
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23
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Khan S, Shahbaaz M, Bisetty K, Ahmad F, Hassan MI. Classification and Functional Analyses of Putative Conserved Proteins from Chlamydophila pneumoniae CWL029. Interdiscip Sci 2015; 9:96-106. [PMID: 26649559 DOI: 10.1007/s12539-015-0134-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 11/19/2015] [Accepted: 11/24/2015] [Indexed: 12/01/2022]
Abstract
Chlamydophila pneumoniae, a Gram-negative bacterium belongs to the family Chlamydiaceae, is known to cause community-acquired pneumonia and bronchitis. There is a need for genomic analyses of C. pneumoniae as its chronic infections result in reactive airway disease, lung cancer and asthma. Recent advancement in the sequencing techniques led to the generation of large genomic data. In order to utilize these data, sequence-based function predictions were used for annotating the uncharacterized genes. The genome of C. pneumoniae encodes 1052 proteins, which include a group of 366 functionally uncharacterized proteins, known as "hypothetical proteins" (HPs). Functions of these HPs were predicted by utilizing an integrated approach that combines varieties of bioinformatics tools. The functions of 142 proteins were successfully predicted and categorized into different classes of enzymes, transport proteins, binding proteins and virulence factors. Among these functionally annotated HPs, we were able to identify 12 virulent HPs. Furthermore, the HP with the highest virulence score was subjected to molecular dynamics (MD) simulations to better understand their dynamical behavior in explicit water conditions. These analyses could be utilized for an in-depth understanding of virulence mechanism. The functional knowledge of these proteins could be useful in drug design and discovery process of infections caused by C. pneumoniae.
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Affiliation(s)
- Shama Khan
- Center for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Mohd Shahbaaz
- Department of Chemistry, Durban University of Technology, Durban, 4000, South Africa
| | - Krishna Bisetty
- Department of Chemistry, Durban University of Technology, Durban, 4000, South Africa
| | - Faizan Ahmad
- Center for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Md Imtaiyaz Hassan
- Center for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India.
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24
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Abstract
This review focuses on the steps unique to methionine biosynthesis, namely the conversion of homoserine to methionine. The past decade has provided a wealth of information concerning the details of methionine metabolism and the review focuses on providing a comprehensive overview of the field, emphasizing more recent findings. Details of methionine biosynthesis are addressed along with key cellular aspects, including regulation, uptake, utilization, AdoMet, the methyl cycle, and growing evidence that inhibition of methionine biosynthesis occurs under stressful cellular conditions. The first unique step in methionine biosynthesis is catalyzed by the metA gene product, homoserine transsuccinylase (HTS, or homoserine O-succinyltransferase). Recent experiments suggest that transcription of these genes is indeed regulated by MetJ, although the repressor-binding sites have not yet been verified. Methionine also serves as the precursor of S-adenosylmethionine, which is an essential molecule employed in numerous biological processes. S-adenosylhomocysteine is produced as a consequence of the numerous AdoMet-dependent methyl transfer reactions that occur within the cell. In E. coli and Salmonella, this molecule is recycled in two discrete steps to complete the methyl cycle. Cultures challenged by oxidative stress appear to experience a growth limitation that depends on methionine levels. E. coli that are deficient for the manganese and iron superoxide dismutases (the sodA and sodB gene products, respectively) require the addition of methionine or cysteine for aerobic growth. Modulation of methionine levels in response to stressful conditions further increases the complexity of its regulation.
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25
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Tavares AH, Fernandes L, Bocca AL, Silva-Pereira I, Felipe MS. Transcriptomic reprogramming of genus Paracoccidioides in dimorphism and host niches. Fungal Genet Biol 2015; 81:98-109. [DOI: 10.1016/j.fgb.2014.01.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 01/27/2014] [Accepted: 01/31/2014] [Indexed: 01/04/2023]
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26
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Shahbaaz M, Ahmad F, Imtaiyaz Hassan M. Structure-based functional annotation of putative conserved proteins having lyase activity from Haemophilus influenzae. 3 Biotech 2015; 5:317-336. [PMID: 28324295 PMCID: PMC4434415 DOI: 10.1007/s13205-014-0231-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Accepted: 05/28/2014] [Indexed: 12/20/2022] Open
Abstract
Haemophilus influenzae is a small pleomorphic Gram-negative bacteria which causes several chronic diseases, including bacteremia, meningitis, cellulitis, epiglottitis, septic arthritis, pneumonia, and empyema. Here we extensively analyzed the sequenced genome of H. influenzae strain Rd KW20 using protein family databases, protein structure prediction, pathways and genome context methods to assign a precise function to proteins whose functions are unknown. These proteins are termed as hypothetical proteins (HPs), for which no experimental information is available. Function prediction of these proteins would surely be supportive to precisely understand the biochemical pathways and mechanism of pathogenesis of Haemophilus influenzae. During the extensive analysis of H. influenzae genome, we found the presence of eight HPs showing lyase activity. Subsequently, we modeled and analyzed three-dimensional structure of all these HPs to determine their functions more precisely. We found these HPs possess cystathionine-β-synthase, cyclase, carboxymuconolactone decarboxylase, pseudouridine synthase A and C, D-tagatose-1,6-bisphosphate aldolase and aminodeoxychorismate lyase-like features, indicating their corresponding functions in the H. influenzae. Lyases are actively involved in the regulation of biosynthesis of various hormones, metabolic pathways, signal transduction, and DNA repair. Lyases are also considered as a key player for various biological processes. These enzymes are critically essential for the survival and pathogenesis of H. influenzae and, therefore, these enzymes may be considered as a potential target for structure-based rational drug design. Our structure–function relationship analysis will be useful to search and design potential lead molecules based on the structure of these lyases, for drug design and discovery.
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Affiliation(s)
- Mohd Shahbaaz
- Department of Computer Science, Jamia Millia Islamia, New Delhi, 110025, India
| | - Faizan Ahmad
- Center for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Md Imtaiyaz Hassan
- Center for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India.
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27
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Mou KT, Muppirala UK, Severin AJ, Clark TA, Boitano M, Plummer PJ. A comparative analysis of methylome profiles of Campylobacter jejuni sheep abortion isolate and gastroenteric strains using PacBio data. Front Microbiol 2015; 5:782. [PMID: 25642218 PMCID: PMC4294202 DOI: 10.3389/fmicb.2014.00782] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 12/20/2014] [Indexed: 12/13/2022] Open
Abstract
Campylobacter jejuni is a leading cause of human gastrointestinal disease and small ruminant abortions in the United States. The recent emergence of a highly virulent, tetracycline-resistant C. jejuni subsp. jejuni sheep abortion clone (clone SA) in the United States, and that strain's association with human disease, has resulted in a heightened awareness of the zoonotic potential of this organism. Pacific Biosciences' Single Molecule, Real-Time sequencing technology was used to explore the variation in the genome-wide methylation patterns of the abortifacient clone SA (IA3902) and phenotypically distinct gastrointestinal-specific C. jejuni strains (NCTC 11168 and 81-176). Several notable differences were discovered that distinguished the methylome of IA3902 from that of 11168 and 81-176: identification of motifs novel to IA3902, genome-specific hypo- and hypermethylated regions, strain level variability in genes methylated, and differences in the types of methylation motifs present in each strain. These observations suggest a possible role of methylation in the contrasting disease presentations of these three C. jejuni strains. In addition, the methylation profiles between IA3902 and a luxS mutant were explored to determine if variations in methylation patterns could be identified that might explain the role of LuxS-dependent methyl recycling in IA3902 abortifacient potential.
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Affiliation(s)
- Kathy T Mou
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University Ames, IA, USA
| | - Usha K Muppirala
- Genome Informatics Facility, Office of Biotechnology, Iowa State University Ames, IA, USA
| | - Andrew J Severin
- Genome Informatics Facility, Office of Biotechnology, Iowa State University Ames, IA, USA
| | | | | | - Paul J Plummer
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University Ames, IA, USA
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Inhibitors of amino acids biosynthesis as antifungal agents. Amino Acids 2014; 47:227-49. [PMID: 25408465 PMCID: PMC4302243 DOI: 10.1007/s00726-014-1873-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 11/05/2014] [Indexed: 12/22/2022]
Abstract
Fungal microorganisms, including the human pathogenic yeast and filamentous fungi, are able to synthesize all proteinogenic amino acids, including nine that are essential for humans. A number of enzymes catalyzing particular steps of human-essential amino acid biosynthesis are fungi specific. Numerous studies have shown that auxotrophic mutants of human pathogenic fungi impaired in biosynthesis of particular amino acids exhibit growth defect or at least reduced virulence under in vivo conditions. Several chemical compounds inhibiting activity of one of these enzymes exhibit good antifungal in vitro activity in minimal growth media, which is not always confirmed under in vivo conditions. This article provides a comprehensive overview of the present knowledge on pathways of amino acids biosynthesis in fungi, with a special emphasis put on enzymes catalyzing particular steps of these pathways as potential targets for antifungal chemotherapy.
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Nguyen DQ, Ngo HPT, Ahn YJ, Lee SH, Kang LW. Expression, crystallization and preliminary X-ray crystallographic analysis of cystathionine β-lyase from Acinetobacter baumannii OXA-23. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2014; 70:1368-71. [PMID: 25286941 DOI: 10.1107/s2053230x14017981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 08/05/2014] [Indexed: 11/11/2022]
Abstract
Multidrug-resistant Acinetobacter baumannii (Ab) has emerged as a leading nosocomial pathogen because of its resistance to most currently available antibiotics. Cystathionine β-lyase (CBL), a pyridoxal 5'-phosphate (PLP)-dependent enzyme, catalyzes the second step in the transsulfuration pathway, which is essential for the metabolic interconversion of the sulfur-containing amino acids homocysteine and methionine. The enzymes of the transsulfuration pathway are considered to be attractive drug targets owing to their specificity to microbes and plants. As a potential target for the development of novel antibacterial drugs, the AbCBL protein was expressed, purified and crystallized. An AbCBL crystal diffracted to 1.57 Å resolution and belonged to the trigonal space group P3112, with unit-cell parameters a = b = 102.9, c = 136.5 Å. The asymmetric unit contained two monomers, with a corresponding VM of 2.3 Å(3) Da(-1) and a solvent content of 46.9%.
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Affiliation(s)
- Diem Quynh Nguyen
- Department of Biological Sciences, Konkuk University, 1 Hwayang dong, Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Ho Phuong Thuy Ngo
- Department of Biological Sciences, Konkuk University, 1 Hwayang dong, Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Yeh Jin Ahn
- Department of Life Science, College of Natural Sciences, Sangmyung University, 7 Hongji-dong, Jongno-gu, Seoul 110-743, Republic of Korea
| | - Sang Hee Lee
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University, 116 Myongji-ro, Yongin, Gyeonggido 449-728, Republic of Korea
| | - Lin Woo Kang
- Department of Biological Sciences, Konkuk University, 1 Hwayang dong, Gwangjin-gu, Seoul 143-701, Republic of Korea
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He X, Slupsky CM. Metabolic fingerprint of dimethyl sulfone (DMSO2) in microbial-mammalian co-metabolism. J Proteome Res 2014; 13:5281-92. [PMID: 25245235 DOI: 10.1021/pr500629t] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
There is growing awareness that intestinal microbiota alters the energy harvesting capacity of the host and regulates metabolism. It has been postulated that intestinal microbiota are able to degrade unabsorbed dietary components and transform xenobiotic compounds. The resulting microbial metabolites derived from the gastrointestinal tract can potentially enter the circulation system, which, in turn, affects host metabolism. Yet, the metabolic capacity of intestinal microbiota and its interaction with mammalian metabolism remains largely unexplored. Here, we review a metabolic pathway that integrates the microbial catabolism of methionine with mammalian metabolism of methanethiol (MT), dimethyl sulfide (DMS), and dimethyl sulfoxide (DMSO), which together provide evidence that supports the microbial origin of dimethyl sulfone (DMSO2) in the human metabolome. Understanding the pathway of DMSO2 co-metabolism expends our knowledge of microbial-derived metabolites and motivates future metabolomics-based studies on ascertaining the metabolic consequences of intestinal microbiota on human health, including detoxification processes and sulfur xenobiotic metabolism.
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Affiliation(s)
- Xuan He
- Department of Nutrition, Department of Food Science and Technology, One Shields Avenue , University of California, Davis, Davis, California 95616, United States
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31
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Shahbaaz M, Hassan MI, Ahmad F. Functional annotation of conserved hypothetical proteins from Haemophilus influenzae Rd KW20. PLoS One 2013; 8:e84263. [PMID: 24391926 PMCID: PMC3877243 DOI: 10.1371/journal.pone.0084263] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 11/21/2013] [Indexed: 11/18/2022] Open
Abstract
Haemophilus influenzae is a Gram negative bacterium that belongs to the family Pasteurellaceae, causes bacteremia, pneumonia and acute bacterial meningitis in infants. The emergence of multi-drug resistance H. influenzae strain in clinical isolates demands the development of better/new drugs against this pathogen. Our study combines a number of bioinformatics tools for function predictions of previously not assigned proteins in the genome of H. influenzae. This genome was extensively analyzed and found 1,657 functional proteins in which function of 429 proteins are unknown, termed as hypothetical proteins (HPs). Amino acid sequences of all 429 HPs were extensively annotated and we successfully assigned the function to 296 HPs with high confidence. We also characterized the function of 124 HPs precisely, but with less confidence. We believed that sequence of a protein can be used as a framework to explain known functional properties. Here we have combined the latest versions of protein family databases, protein motifs, intrinsic features from the amino acid sequence, pathway and genome context methods to assign a precise function to hypothetical proteins for which no experimental information is available. We found these HPs belong to various classes of proteins such as enzymes, transporters, carriers, receptors, signal transducers, binding proteins, virulence and other proteins. The outcome of this work will be helpful for a better understanding of the mechanism of pathogenesis and in finding novel therapeutic targets for H. influenzae.
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Affiliation(s)
- Mohd Shahbaaz
- Department of Computer Science, Jamia Millia Islamia, Jamia Nagar, New Delhi, India
| | - Md Imtaiyaz Hassan
- Center for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, India
| | - Faizan Ahmad
- Center for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, India
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Characterization of C-S Lyase from C. diphtheriae: a possible target for new antimicrobial drugs. BIOMED RESEARCH INTERNATIONAL 2013; 2013:701536. [PMID: 24106714 PMCID: PMC3784150 DOI: 10.1155/2013/701536] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 07/16/2013] [Indexed: 12/28/2022]
Abstract
The emergence of antibiotic resistance in microbial pathogens requires the identification of new antibacterial drugs. The biosynthesis of methionine is an attractive target because of its central importance in cellular metabolism. Moreover, most of the steps in methionine biosynthesis pathway are absent in mammals, lowering the probability of unwanted side effects. Herein, detailed biochemical characterization of one enzyme required for methionine biosynthesis, a pyridoxal-5′-phosphate (PLP-) dependent C-S lyase from Corynebacterium diphtheriae, a pathogenic bacterium that causes diphtheria, has been performed. We overexpressed the protein in E. coli and analyzed substrate specificity, pH dependence of steady state kinetic parameters, and ligand-induced spectral transitions of the protein. Structural comparison of the enzyme with cystalysin from Treponema denticola indicates a similarity in overall folding. We used site-directed mutagenesis to highlight the importance of active site residues Tyr55, Tyr114, and Arg351, analyzing the effects of amino acid replacement on catalytic properties of enzyme. Better understanding of the active site of C. diphtheriae C-S lyase and the determinants of substrate and reaction specificity from this work will facilitate the design of novel inhibitors as antibacterial therapeutics.
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Regulation of sulphur assimilation is essential for virulence and affects iron homeostasis of the human-pathogenic mould Aspergillus fumigatus. PLoS Pathog 2013; 9:e1003573. [PMID: 24009505 PMCID: PMC3757043 DOI: 10.1371/journal.ppat.1003573] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 07/08/2013] [Indexed: 11/19/2022] Open
Abstract
Sulphur is an essential element that all pathogens have to absorb from their surroundings in order to grow inside their infected host. Despite its importance, the relevance of sulphur assimilation in fungal virulence is largely unexplored. Here we report a role of the bZIP transcription factor MetR in sulphur assimilation and virulence of the human pathogen Aspergillus fumigatus. The MetR regulator is essential for growth on a variety of sulphur sources; remarkably, it is fundamental for assimilation of inorganic S-sources but dispensable for utilization of methionine. Accordingly, it strongly supports expression of genes directly related to inorganic sulphur assimilation but not of genes connected to methionine metabolism. On a broader scale, MetR orchestrates the comprehensive transcriptional adaptation to sulphur-starving conditions as demonstrated by digital gene expression analysis. Surprisingly, A. fumigatus is able to utilize volatile sulphur compounds produced by its methionine catabolism, a process that has not been described before and that is MetR-dependent. The A. fumigatus MetR transcriptional activator is important for virulence in both leukopenic mice and an alternative mini-host model of aspergillosis, as it was essential for the development of pulmonary aspergillosis and supported the systemic dissemination of the fungus. MetR action under sulphur-starving conditions is further required for proper iron regulation, which links regulation of sulphur metabolism to iron homeostasis and demonstrates an unprecedented regulatory crosstalk. Taken together, this study provides evidence that regulation of sulphur assimilation is not only crucial for A. fumigatus virulence but also affects the balance of iron in this prime opportunistic pathogen.
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Cystathionine β-Lyase-Like Protein with Pyridoxal Binding Domain Characterized in Leishmania major by Comparative Sequence Analysis and Homology Modelling. ACTA ACUST UNITED AC 2013. [DOI: 10.1155/2013/520435] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cystathionine β-lyase-like protein (CBLP), one of the key enzymes involved in methionine biosynthesis utilising pyridoxal phosphate (PLP) as a cofactor, has recently been reported in Leishmania major. Its presence in the parasite and absence in humans warrant its full characterisation and fruition as a potent, selective, and inevitable druggable target. Due to the unavailability of X-ray 3D structure of CBLP, a homology model for this protein was developed for the first time. The model was evaluated for PLP binding site and various conserve domain residues of the protein recommended by comparative sequence analyses by different protein analysis tools. The model was validated and discovered to be robust and statistically significant. The final model was superimposed on template of Arabidopsis thaliana (PDB ID: 1IBJ) and RMSD was found to be 0.486. The PLP binding site residues of both the proteins were ensued to be highly conserved indicated by Gly71, Met72, Tyr95, Asp169, and Ser193 as well as formation of aldimine bond with Lys194. This was further verified through molecular simulation of PLP into the cofactor binding site of the modelled protein. The present study may therefore play a directing role in the designing of novel, potential, and selective antileishmanial agents.
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Comparative genomic analysis of the genus Nocardiopsis provides new insights into its genetic mechanisms of environmental adaptability. PLoS One 2013; 8:e61528. [PMID: 23626695 PMCID: PMC3634020 DOI: 10.1371/journal.pone.0061528] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 03/12/2013] [Indexed: 12/04/2022] Open
Abstract
The genus Nocardiopsis, a widespread group in phylum Actinobacteria, has received much attention owing to its ecological versatility, pathogenicity, and ability to produce a rich array of bioactive metabolites. Its high environmental adaptability might be attributable to its genome dynamics, which can be estimated through comparative genomic analysis targeting microorganisms with close phylogenetic relationships but different phenotypes. To shed light on speciation, gene content evolution, and environmental adaptation in these unique actinobacteria, we sequenced draft genomes for 16 representative species of the genus and compared them with that of the type species N. dassonvillei subsp. dassonvillei DSM 43111T. The core genome of 1,993 orthologous and paralogous gene clusters was identified, and the pan-genomic reservoir was found not only to accommodate more than 22,000 genes, but also to be open. The top ten paralogous genes in terms of copy number could be referred to three functional categories: transcription regulators, transporters, and synthases related to bioactive metabolites. Based on phylogenomic reconstruction, we inferred past evolutionary events, such as gene gains and losses, and identified a list of clade-specific genes implicated in environmental adaptation. These results provided insights into the genetic causes of environmental adaptability in this cosmopolitan actinobacterial group and the contributions made by its inherent features, including genome dynamics and the constituents of core and accessory proteins.
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36
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Glyphosate’s Suppression of Cytochrome P450 Enzymes and Amino Acid Biosynthesis by the Gut Microbiome: Pathways to Modern Diseases. ENTROPY 2013. [DOI: 10.3390/e15041416] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Basavanna S, Chimalapati S, Maqbool A, Rubbo B, Yuste J, Wilson RJ, Hosie A, Ogunniyi AD, Paton JC, Thomas G, Brown JS. The effects of methionine acquisition and synthesis on Streptococcus pneumoniae growth and virulence. PLoS One 2013; 8:e49638. [PMID: 23349662 PMCID: PMC3551916 DOI: 10.1371/journal.pone.0049638] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 10/16/2012] [Indexed: 11/19/2022] Open
Abstract
Bacterial pathogens need to acquire nutrients from the host, but for many nutrients their importance during infection remain poorly understood. We have investigated the importance of methionine acquisition and synthesis for Streptococcus pneumoniae growth and virulence using strains with gene deletions affecting a putative methionine ABC transporter lipoprotein (Sp_0149, metQ) and/or methionine biosynthesis enzymes (Sp_0585 - Sp_0586, metE and metF). Immunoblot analysis confirmed MetQ was a lipoprotein and present in all S. pneumoniae strains investigated. However, vaccination with MetQ did not prevent fatal S. pneumoniae infection in mice despite stimulating a strong specific IgG response. Tryptophan fluorescence spectroscopy and isothermal titration calorimetry demonstrated that MetQ has both a high affinity and specificity for L-methionine with a KD of ∼25 nM, and a ΔmetQ strain had reduced uptake of C14-methionine. Growth of the ΔmetQ/ΔmetEF strain was greatly impaired in chemically defined medium containing low concentrations of methionine and in blood but was partially restored by addition of high concentrations of exogenous methionine. Mixed infection models showed no attenuation of the ΔmetQ, ΔmetEF and ΔmetQ/ΔmetEF strains in their ability to colonise the mouse nasopharnyx. In a mouse model of systemic infection although significant infection was established in all mice, there were reduced spleen bacterial CFU after infection with the ΔmetQ/ΔmetEF strain compared to the wild-type strain. These data demonstrate that Sp_0149 encodes a high affinity methionine ABC transporter lipoprotein and that Sp_0585 – Sp_0586 are likely to be required for methionine synthesis. Although Sp_0149 and Sp_0585-Sp_0586 make a contribution towards full virulence, neither was essential for S. pneumoniae survival during infection.
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Affiliation(s)
- Shilpa Basavanna
- Department of Microbiology and Molecular Genetics, University of Texas-Houston Medical School, Houston, Texas, United States of America
| | - Suneeta Chimalapati
- Department of Medicine, Centre for Inflammation and Tissue Repair, University College Medical School, Rayne Institute, London, United Kingdom
| | - Abbas Maqbool
- Department of Biology (Area 10), University of York, York, United Kingdom
| | - Bruna Rubbo
- Department of Medicine, Centre for Inflammation and Tissue Repair, University College Medical School, Rayne Institute, London, United Kingdom
| | - Jose Yuste
- Centro de Investigaciones Biologicas, CSIC and CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Robert J. Wilson
- Department of Medicine, Centre for Inflammation and Tissue Repair, University College Medical School, Rayne Institute, London, United Kingdom
| | - Arthur Hosie
- Division of Science, University of Bedfordshire, Park Square, Luton, Bedfordshire, United Kingdom
| | - Abiodun D. Ogunniyi
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, South Australia, Australia
| | - James C. Paton
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, South Australia, Australia
| | - Gavin Thomas
- Department of Biology (Area 10), University of York, York, United Kingdom
| | - Jeremy S. Brown
- Department of Medicine, Centre for Inflammation and Tissue Repair, University College Medical School, Rayne Institute, London, United Kingdom
- * E-mail:
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Ihnatko R, Shaw E, Toman R. Proteome of Coxiella burnetii. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 984:105-30. [DOI: 10.1007/978-94-007-4315-1_6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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39
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Holt S, Cordente AG, Williams SJ, Capone DL, Jitjaroen W, Menz IR, Curtin C, Anderson PA. Engineering Saccharomyces cerevisiae to release 3-Mercaptohexan-1-ol during fermentation through overexpression of an S. cerevisiae Gene, STR3, for improvement of wine aroma. Appl Environ Microbiol 2011; 77:3626-32. [PMID: 21478306 PMCID: PMC3127618 DOI: 10.1128/aem.03009-10] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 03/26/2011] [Indexed: 11/20/2022] Open
Abstract
Sulfur-containing aroma compounds are key contributors to the flavor of a diverse range of foods and beverages. The tropical fruit characters of Vitis vinifera L. cv. Sauvignon blanc wines are attributed to the presence of the aromatic thiols 3-mercaptohexan-1-ol (3MH), 3-mercaptohexan-1-ol-acetate, and 4-mercapto-4-methylpentan-2-one (4MMP). These volatile thiols are found in small amounts in grape juice and are formed from nonvolatile cysteinylated precursors during fermentation. In this study, we overexpressed a Saccharomyces cerevisiae gene, STR3, which led to an increase in 3MH release during fermentation of a V. vinifera L. cv. Sauvignon blanc juice. Characterization of the enzymatic properties of Str3p confirmed it to be a pyridoxal-5'-phosphate-dependent cystathionine β-lyase, and we demonstrated that this enzyme was able to cleave the cysteinylated precursors of 3MH and 4MMP to release the free thiols. These data provide direct evidence for a yeast enzyme able to release aromatic thiols in vitro that can be applied in the development of self-cloned yeast to enhance wine flavor.
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Affiliation(s)
- Sylvester Holt
- University of Copenhagen, Copenhagen, Denmark
- School of Biological Sciences, Flinders University, Adelaide, SA, Australia
| | | | - Simon J. Williams
- School of Biological Sciences, Flinders University, Adelaide, SA, Australia
| | | | | | - Ian R. Menz
- School of Biological Sciences, Flinders University, Adelaide, SA, Australia
| | - Chris Curtin
- The Australian Wine Research Institute, Adelaide, SA, Australia
| | - Peter A. Anderson
- School of Biological Sciences, Flinders University, Adelaide, SA, Australia
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40
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De Pascale G, Nazi I, Harrison PHM, Wright GD. β-Lactone natural products and derivatives inactivate homoserine transacetylase, a target for antimicrobial agents. J Antibiot (Tokyo) 2011; 64:483-7. [DOI: 10.1038/ja.2011.37] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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41
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Regulation of sulfur assimilation pathways in Burkholderia cenocepacia through control of genes by the SsuR transcription factor. J Bacteriol 2011; 193:1843-53. [PMID: 21317335 DOI: 10.1128/jb.00483-10] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genome of Burkholderia cenocepacia contains two genes encoding closely related LysR-type transcriptional regulators, CysB and SsuR, involved in control of sulfur assimilation processes. In this study we show that the function of SsuR is essential for the utilization of a number of organic sulfur sources of either environmental or human origin. Among the genes upregulated by SsuR identified here are the tauABC operon encoding a predicted taurine transporter, three tauD-type genes encoding putative taurine dioxygenases, and atsA encoding a putative arylsulfatase. The role of SsuR in expression of these genes/operons was characterized through (i) construction of transcriptional reporter fusions to candidate promoter regions and analysis of their expression in the presence/absence of SsuR and (ii) testing the ability of SsuR to bind SsuR-responsive promoter regions. We also demonstrate that expression of SsuR-activated genes is not repressed in the presence of inorganic sulfate. A more detailed analysis of four SsuR-responsive promoter regions indicated that ~44 bp of the DNA sequence preceding and/or overlapping the predicted -35 element of such promoters is sufficient for SsuR binding. The DNA sequence homology among SsuR "recognition motifs" at different responsive promoters appears to be limited.
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42
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In Vivo Studies of Clostridium perfringens in Mouse Gas Gangrene Model. Curr Microbiol 2010; 62:999-1008. [DOI: 10.1007/s00284-010-9821-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 11/05/2010] [Indexed: 10/18/2022]
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The pleiotropic CymR regulator of Staphylococcus aureus plays an important role in virulence and stress response. PLoS Pathog 2010; 6:e1000894. [PMID: 20485570 PMCID: PMC2869319 DOI: 10.1371/journal.ppat.1000894] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Accepted: 04/02/2010] [Indexed: 12/20/2022] Open
Abstract
We have characterized a novel pleiotropic role for CymR, the master regulator of cysteine metabolism. We show here that CymR plays an important role both in stress response and virulence of Staphylococcus aureus. Genes involved in detoxification processes, including oxidative stress response and metal ion homeostasis, were differentially expressed in a ΔcymR mutant. Deletion of cymR resulted in increased sensitivity to hydrogen peroxide-, disulfide-, tellurite- and copper-induced stresses. Estimation of metabolite pools suggests that this heightened sensitivity could be the result of profound metabolic changes in the ΔcymR mutant, with an increase in the intracellular cysteine pool and hydrogen sulfide formation. Since resistance to oxidative stress within the host organism is important for pathogen survival, we investigated the role of CymR during the infectious process. Our results indicate that the deletion of cymR promotes survival of S. aureus inside macrophages, whereas virulence of the ΔcymR mutant is highly impaired in mice. These data indicate that CymR plays a major role in virulence and adaptation of S. aureus for survival within the host. Staphylococcus aureus is a very harmful human pathogen that is a major cause of nosocomial infections. Humans have developed sophisticated defense strategies against invading bacteria, including the innate immune response, with the generation of an oxidative burst inside phagocytic cells. Staphylococcal infections are extremely difficult to eradicate due to the remarkable capacity of these bacteria to adapt to different environmental conditions both inside and outside the host organism. Sulfur metabolism is essential for all living organisms and is tightly controlled by regulatory proteins. In this paper, we revealed an important role for CymR, a major regulator of sulfur metabolism, in adaptation of S. aureus to the host environment. Inactivation of the gene encoding this regulator in S. aureus leads to a mutant bacterium with increased vulnerability to stress conditions including oxidative stress encountered inside the host. More importantly, the deletion of the cymR gene strongly affected the interaction of S. aureus with its host, leading to impaired virulence in mice. Our results place CymR among the potential targets for attenuation of S. aureus infections.
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Soutourina O, Poupel O, Coppée JY, Danchin A, Msadek T, Martin-Verstraete I. CymR, the master regulator of cysteine metabolism inStaphylococcus aureus, controls host sulphur source utilization and plays a role in biofilm formation. Mol Microbiol 2009; 73:194-211. [DOI: 10.1111/j.1365-2958.2009.06760.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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45
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Troccaz M, Benattia F, Borchard G, Clark AJ. Properties of recombinant Staphylococcus haemolyticus cystathionine beta-lyase (metC) and its potential role in the generation of volatile thiols in axillary malodor. Chem Biodivers 2009; 5:2372-85. [PMID: 19035565 DOI: 10.1002/cbdv.200890202] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Enzymes implicated in cysteine and methionine metabolism such as cystathionine beta-lyase (CBL; EC 4.4.1.8), a pyridoxal-5'-phosphate (PLP)-dependent carbon-sulfur lyase, have been shown to play a central role in the generation of sulfur compounds. This work describes the unprecedented cloning and characterization of the metC-cystathionine beta-lyase from the axillary-isolated strain Staphylococcus haemolyticus AX3, in order to determine its activity and its involvement in amino acid biosynthesis, and in the generation of sulfur compounds in human sweat. The gene contains a cysteine/methionine metabolism enzyme pattern, and also a sequence capable to effect beta-elimination. The recombinant enzyme was shown to cleave cystathionine into homocysteine and to convert methionine into methanethiol at low levels. No odor was generated after incubation of the recombinant enzyme with sterile human axillary secretions; sweat components were found to have an inhibitory effect. These results suggest that the generation of sulfur compounds by Staphylococci and the beta-lyase activity in human sweat are mediated by enzymes other than the metC gene or by the concerted activities of more than one enzyme.
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Affiliation(s)
- Myriam Troccaz
- Firmenich SA, Corporate R&D Division, P. O. Box 239, CH-1211 Geneva 8.
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46
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Starkenmann C, Troccaz M, Howell K. The role of cysteine and cysteine-S conjugates as odour precursors in the flavour and fragrance industry. FLAVOUR FRAG J 2008. [DOI: 10.1002/ffj.1907] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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47
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Sperandio B, Gautier C, McGovern S, Ehrlich DS, Renault P, Martin-Verstraete I, Guédon E. Control of methionine synthesis and uptake by MetR and homocysteine in Streptococcus mutans. J Bacteriol 2007; 189:7032-44. [PMID: 17675375 PMCID: PMC2045202 DOI: 10.1128/jb.00703-07] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
MetR (formerly Smu.1225), a regulator of the LysR family, controls key genes for methionine supply in Streptococcus mutans. An S. mutans metR mutant is unable to transport l-methionine and to grow in the absence of this amino acid. Accordingly, MetR activates transcription by binding to the promoter regions of two gene clusters and smu.1487, whose products are involved in methionine biosynthesis (MetEF and Smu.1487) and uptake (AtmBDE). Transcriptional activation by MetR requires the presence of a 17-bp palindromic sequence, the Met box. Base substitutions in the Met box hinder the formation of a MetR-DNA complex and abolish MetR-dependent activation, showing that Met boxes correspond to MetR recognition sites. Activation by MetR occurs in methionine-depleted medium and is rapidly triggered under nonactivating conditions by the addition of homocysteine. This intermediate of methionine biosynthesis increases the affinity of MetR for DNA in vitro and appears to be the MetR coeffector in vivo. Homocysteine plays a crucial role in methionine metabolic gene regulation by controlling MetR activity. A similar mechanism of homocysteine- and MetR-dependent control of methionine biosynthetic genes operates in S. thermophilus. These data suggest a common mechanism for the regulation of the methionine supply in streptococci. However, some streptococcal species are unable to synthesize the homocysteine coeffector. This intriguing feature is discussed in the light of comparative genomics and streptococcal ecology.
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Affiliation(s)
- Brice Sperandio
- Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, 78352 Jouy-en-Josas Cedex, France
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48
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Abstract
The identification of new antibacterial targets is urgently needed to address multidrug resistant and latent tuberculosis infection. Sulfur metabolic pathways are essential for survival and the expression of virulence in many pathogenic bacteria, including Mycobacterium tuberculosis. In addition, microbial sulfur metabolic pathways are largely absent in humans and therefore, represent unique targets for therapeutic intervention. In this review, we summarize our current understanding of the enzymes associated with the production of sulfated and reduced sulfur-containing metabolites in Mycobacteria. Small molecule inhibitors of these catalysts represent valuable chemical tools that can be used to investigate the role of sulfur metabolism throughout the Mycobacterial lifecycle and may also represent new leads for drug development. In this light, we also summarize recent progress in the development of inhibitors of sulfur metabolism enzymes.
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Affiliation(s)
- Devayani P. Bhave
- Chemical Biology Ph.D. Program, University of Michigan, Ann Arbor, Michigan, 48109-2216
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, 48109-2216
| | - Wilson B. Muse
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, 48109-2216
| | - Kate S. Carroll
- Chemical Biology Ph.D. Program, University of Michigan, Ann Arbor, Michigan, 48109-2216
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, 48109-2216
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, 48109-2216
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49
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Tavares AHFP, Silva SS, Dantas A, Campos EG, Andrade RV, Maranhão AQ, Brígido MM, Passos-Silva DG, Fachin AL, Teixeira SMR, Passos GAS, Soares CMA, Bocca AL, Carvalho MJA, Silva-Pereira I, Felipe MSS. Early transcriptional response of Paracoccidioides brasiliensis upon internalization by murine macrophages. Microbes Infect 2007; 9:583-90. [PMID: 17387029 DOI: 10.1016/j.micinf.2007.01.024] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2006] [Revised: 01/17/2007] [Accepted: 01/30/2007] [Indexed: 11/15/2022]
Abstract
Paracoccidioides brasiliensis, a thermal dimorphic fungus, is the etiologic agent of the most common systemic mycosis in Latin America, paracoccidioidomycosis. The yeast form of P. brasiliensis acts as a facultative intracellular pathogen being able to survive and replicate within the phagosome of nonactivated murine and human macrophages. This ability has been proposed to be crucial to the development of disease. Thus, P. brasiliensis may have evolved mechanisms that counteract the constraints imposed by phagocytic cells. By using cDNA microarray technology we evaluated the early transcriptional response of this fungus to the environment of peritoneal murine macrophages in order to shed light on the mechanisms used by P. brasiliensis to survive within phagocytic cells. Of the 1152 genes analyzed, we identified 152 genes that were differentially transcribed. Intracellularly expressed genes were primarily associated with glucose and amino acid limitation, cell wall construction, and oxidative stress. For the first time, a comprehensive gene expression tool is used for the expression analysis of P. brasiliensis genes when interacting with macrophages. Overall, our data show a transcriptional plasticity of P. brasiliensis in response to the harsh environment of macrophages which may lead to adaptation and consequent survival of this pathogen.
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Affiliation(s)
- Aldo Henrique F P Tavares
- Departamento de Biologia Celular, Laboratório de Biologia Molecular, Universidade de Brasília-Unb Brasília, Campus Darcy Ribeiro-Asa Norte 70910-900, Brasília, DF, Brazil
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50
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Nazi I, Scott A, Sham A, Rossi L, Williamson PR, Kronstad JW, Wright GD. Role of homoserine transacetylase as a new target for antifungal agents. Antimicrob Agents Chemother 2007; 51:1731-6. [PMID: 17353245 PMCID: PMC1855549 DOI: 10.1128/aac.01400-06] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microbial amino acid biosynthesis is a proven yet underexploited target of antibiotics. The biosynthesis of methionine in particular has been shown to be susceptible to small-molecule inhibition in fungi. The first committed step in Met biosynthesis is the acylation of homoserine (Hse) by the enzyme homoserine transacetylase (HTA). We have identified the MET2 gene of Cryptococcus neoformans H99 that encodes HTA (CnHTA) by complementation of an Escherichia coli metA mutant that lacks the gene encoding homoserine transsuccinylase (HTS). We cloned, expressed, and purified CnHTA and determined its steady-state kinetic parameters for the acetylation of L-Hse by acetyl coenzyme A. We next constructed a MET2 mutant in C. neoformans H99 and tested its growth behavior in Met-deficient media, confirming the expected Met auxotrophy. Furthermore, we used this mutant in a mouse inhalation model of infection and determined that MET2 is required for virulence. This makes fungal HTA a viable target for new antibiotic discovery. We screened a 1,000-compound library of small molecules for HTA inhibitors and report the identification of the first inhibitor of fungal HTA. This work validates HTA as an attractive drug-susceptible target for new antifungal agent design.
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Affiliation(s)
- Ishac Nazi
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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