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Choline Binding Proteins from Streptococcus pneumoniae: A Dual Role as Enzybiotics and Targets for the Design of New Antimicrobials. Antibiotics (Basel) 2016; 5:antibiotics5020021. [PMID: 27314398 PMCID: PMC4929436 DOI: 10.3390/antibiotics5020021] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 05/04/2016] [Accepted: 05/16/2016] [Indexed: 12/20/2022] Open
Abstract
Streptococcus pneumoniae (pneumococcus) is an important pathogen responsible for acute invasive and non-invasive infections such as meningitis, sepsis and otitis media, being the major cause of community-acquired pneumonia. The fight against pneumococcus is currently hampered both by insufficient vaccine coverage and by rising antimicrobial resistances to traditional antibiotics, making necessary the research on novel targets. Choline binding proteins (CBPs) are a family of polypeptides found in pneumococcus and related species, as well as in some of their associated bacteriophages. They are characterized by a structural organization in two modules: a functional module (FM), and a choline-binding module (CBM) that anchors the protein to the choline residues present in the cell wall through non-covalent interactions. Pneumococcal CBPs include cell wall hydrolases, adhesins and other virulence factors, all playing relevant physiological roles for bacterial viability and virulence. Moreover, many pneumococcal phages also make use of hydrolytic CBPs to fulfill their infectivity cycle. Consequently, CBPs may play a dual role for the development of novel antipneumococcal drugs, both as targets for inhibitors of their binding to the cell wall and as active cell lytic agents (enzybiotics). In this article, we review the current state of knowledge about host- and phage-encoded pneumococcal CBPs, with a special focus on structural issues, together with their perspectives for effective anti-infectious treatments.
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152
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Genomic Signatures of Experimental Adaptation to Antimicrobial Peptides in Staphylococcus aureus. G3-GENES GENOMES GENETICS 2016; 6:1535-9. [PMID: 27172179 PMCID: PMC4889650 DOI: 10.1534/g3.115.023622] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The evolution of resistance against antimicrobial peptides has long been considered unlikely due to their mechanism of action, yet experimental selection with antimicrobial peptides (AMPs) results in rapid evolution of resistance in several species of bacteria. Although numerous studies have utilized mutant screens to identify loci that determine AMP susceptibility, there is a dearth of data concerning the genomic changes that accompany experimental evolution of AMP resistance. Using genome resequencing, we analyzed the mutations that arose during experimental evolution of resistance to the cationic AMPs iseganan, melittin, and pexiganan, as well as to a combination of melittin and pexiganan, or to the aminoglycoside antibiotic streptomycin. Analysis of 17 independently replicated Staphylococcus aureus selection lines, including unselected controls, showed that each AMP selected for mutations at distinct loci. We identify mutations in genes involved in the synthesis and maintenance of the cell envelope. These include genes previously identified from mutant screens for AMP resistance, and genes involved in the response to AMPs and cell-wall-active antibiotics. Furthermore, transposon insertion mutants were used to verify that a number of the identified genes are directly involved in determining AMP susceptibility. Strains selected for AMP resistance under controlled experimental evolution displayed consistent AMP-specific mutations in genes that determine AMP susceptibility. This suggests that different routes to evolve resistance are favored within a controlled genetic background.
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153
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Liu Y, Rodrigues JPGLM, Bonvin AMJJ, Zaal EA, Berkers CR, Heger M, Gawarecka K, Swiezewska E, Breukink E, Egmond MR. New Insight into the Catalytic Mechanism of Bacterial MraY from Enzyme Kinetics and Docking Studies. J Biol Chem 2016; 291:15057-68. [PMID: 27226570 DOI: 10.1074/jbc.m116.717884] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Indexed: 01/01/2023] Open
Abstract
Phospho-MurNAc-pentapeptide translocase (MraY) catalyzes the synthesis of Lipid I, a bacterial peptidoglycan precursor. As such, MraY is essential for bacterial survival and therefore is an ideal target for developing novel antibiotics. However, the understanding of its catalytic mechanism, despite the recently determined crystal structure, remains limited. In the present study, the kinetic properties of Bacillus subtilis MraY (BsMraY) were investigated by fluorescence enhancement using dansylated UDP-MurNAc-pentapeptide and heptaprenyl phosphate (C35-P, short-chain homolog of undecaprenyl phosphate, the endogenous substrate of MraY) as second substrate. Varying the concentrations of both of these substrates and fitting the kinetics data to two-substrate models showed that the concomitant binding of both UDP-MurNAc-pentapeptide-DNS and C35-P to the enzyme is required before the release of the two products, Lipid I and UMP. We built a model of BsMraY and performed docking studies with the substrate C35-P to further deepen our understanding of how MraY accommodates this lipid substrate. Based on these modeling studies, a novel catalytic role was put forward for a fully conserved histidine residue in MraY (His-289 in BsMraY), which has been experimentally confirmed to be essential for MraY activity. Using the current model of BsMraY, we propose that a small conformational change is necessary to relocate the His-289 residue, such that the translocase reaction can proceed via a nucleophilic attack of the phosphate moiety of C35-P on bound UDP-MurNAc-pentapeptide.
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Affiliation(s)
- Yao Liu
- From Institute of Biomembranes, Department of Membrane Biochemistry and Biophysics, Utrecht University, 3584 CH, Utrecht, the Netherlands
| | | | | | - Esther A Zaal
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht University, 3584 CH, Utrecht, the Netherlands
| | - Celia R Berkers
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht University, 3584 CH, Utrecht, the Netherlands
| | - Michal Heger
- the Department of Experimental Surgery, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands, and
| | - Katarzyna Gawarecka
- the Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Ewa Swiezewska
- the Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Eefjan Breukink
- From Institute of Biomembranes, Department of Membrane Biochemistry and Biophysics, Utrecht University, 3584 CH, Utrecht, the Netherlands,
| | - Maarten R Egmond
- From Institute of Biomembranes, Department of Membrane Biochemistry and Biophysics, Utrecht University, 3584 CH, Utrecht, the Netherlands
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154
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Kumar A, Thotakura PL, Tiwary BK, Krishna R. Target identification in Fusobacterium nucleatum by subtractive genomics approach and enrichment analysis of host-pathogen protein-protein interactions. BMC Microbiol 2016; 16:84. [PMID: 27176600 PMCID: PMC4866016 DOI: 10.1186/s12866-016-0700-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 05/06/2016] [Indexed: 02/07/2023] Open
Abstract
Background Fusobacterium nucleatum, a well studied bacterium in periodontal diseases, appendicitis, gingivitis, osteomyelitis and pregnancy complications has recently gained attention due to its association with colorectal cancer (CRC) progression. Treatment with berberine was shown to reverse F. nucleatum-induced CRC progression in mice by balancing the growth of opportunistic pathogens in tumor microenvironment. Intestinal microbiota imbalance and the infections caused by F. nucleatum might be regulated by therapeutic intervention. Hence, we aimed to predict drug target proteins in F. nucleatum, through subtractive genomics approach and host-pathogen protein-protein interactions (HP-PPIs). We also carried out enrichment analysis of host interacting partners to hypothesize the possible mechanisms involved in CRC progression due to F. nucleatum. Results In subtractive genomics approach, the essential, virulence and resistance related proteins were retrieved from RefSeq proteome of F. nucleatum by searching against Database of Essential Genes (DEG), Virulence Factor Database (VFDB) and Antibiotic Resistance Gene-ANNOTation (ARG-ANNOT) tool respectively. A subsequent hierarchical screening to identify non-human homologous, metabolic pathway-independent/pathway-specific and druggable proteins resulted in eight pathway-independent and 27 pathway-specific druggable targets. Co-aggregation of F. nucleatum with host induces proinflammatory gene expression thereby potentiates tumorigenesis. Hence, proteins from IBDsite, a database for inflammatory bowel disease (IBD) research and those involved in colorectal adenocarcinoma as interpreted from The Cancer Genome Atlas (TCGA) were retrieved to predict drug targets based on HP-PPIs with F. nucleatum proteome. Prediction of HP-PPIs exhibited 186 interactions contributed by 103 host and 76 bacterial proteins. Bacterial interacting partners were accounted as putative targets. And enrichment analysis of host interacting partners showed statistically enriched terms that were in positive correlation with CRC, atherosclerosis, cardiovascular, osteoporosis, Alzheimer’s and other diseases. Conclusion Subtractive genomics analysis provided a set of target proteins suggested to be indispensable for survival and pathogenicity of F. nucleatum. These target proteins might be considered for designing potent inhibitors to abrogate F. nucleatum infections. From enrichment analysis, it was hypothesized that F. nucleatum infection might enhance CRC progression by simultaneously regulating multiple signaling cascades which could lead to up-regulation of proinflammatory responses, oncogenes, modulation of host immune defense mechanism and suppression of DNA repair system. Electronic supplementary material The online version of this article (doi:10.1186/s12866-016-0700-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Amit Kumar
- Centre for Bioinformatics, Pondicherry University, Puducherry, 605014, India
| | | | - Basant Kumar Tiwary
- Centre Head, Centre for Bioinformatics, Pondicherry University, Puducherry, 605014, India
| | - Ramadas Krishna
- Centre for Bioinformatics, Pondicherry University, Puducherry, 605014, India.
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155
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Laddomada F, Miyachiro MM, Dessen A. Structural Insights into Protein-Protein Interactions Involved in Bacterial Cell Wall Biogenesis. Antibiotics (Basel) 2016; 5:antibiotics5020014. [PMID: 27136593 PMCID: PMC4929429 DOI: 10.3390/antibiotics5020014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 03/15/2016] [Accepted: 04/09/2016] [Indexed: 12/30/2022] Open
Abstract
The bacterial cell wall is essential for survival, and proteins that participate in its biosynthesis have been the targets of antibiotic development efforts for decades. The biosynthesis of its main component, the peptidoglycan, involves the coordinated action of proteins that are involved in multi-member complexes which are essential for cell division (the “divisome”) and/or cell wall elongation (the “elongasome”), in the case of rod-shaped cells. Our knowledge regarding these interactions has greatly benefitted from the visualization of different aspects of the bacterial cell wall and its cytoskeleton by cryoelectron microscopy and tomography, as well as genetic and biochemical screens that have complemented information from high resolution crystal structures of protein complexes involved in divisome or elongasome formation. This review summarizes structural and functional aspects of protein complexes involved in the cytoplasmic and membrane-related steps of peptidoglycan biosynthesis, with a particular focus on protein-protein interactions whereby disruption could lead to the development of novel antibacterial strategies.
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Affiliation(s)
- Federica Laddomada
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, Grenoble F-38044, France.
- Centre National de la Recherche Scientifique (CNRS), IBS, Grenoble F-38044, France.
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), IBS, Grenoble F-38044, France.
| | - Mayara M Miyachiro
- Brazilian National Laboratory for Biosciences (LNBio), CNPEM, Campinas, São Paulo 13083-100, Brazil.
| | - Andréa Dessen
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, Grenoble F-38044, France.
- Centre National de la Recherche Scientifique (CNRS), IBS, Grenoble F-38044, France.
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), IBS, Grenoble F-38044, France.
- Brazilian National Laboratory for Biosciences (LNBio), CNPEM, Campinas, São Paulo 13083-100, Brazil.
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156
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Tsui HCT, Zheng JJ, Magallon AN, Ryan JD, Yunck R, Rued BE, Bernhardt TG, Winkler ME. Suppression of a deletion mutation in the gene encoding essential PBP2b reveals a new lytic transglycosylase involved in peripheral peptidoglycan synthesis in Streptococcus pneumoniae D39. Mol Microbiol 2016; 100:1039-65. [PMID: 26933838 DOI: 10.1111/mmi.13366] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In ellipsoid-shaped ovococcus bacteria, such as the pathogen Streptococcus pneumoniae (pneumococcus), side-wall (peripheral) peptidoglycan (PG) synthesis emanates from midcells and is catalyzed by the essential class B penicillin-binding protein PBP2b transpeptidase (TP). We report that mutations that inactivate the pneumococcal YceG-domain protein, Spd_1346 (renamed MltG), remove the requirement for PBP2b. ΔmltG mutants in unencapsulated strains accumulate inactivation mutations of class A PBP1a, which possesses TP and transglycosylase (TG) activities. The 'synthetic viable' genetic relationship between Δpbp1a and ΔmltG mutations extends to essential ΔmreCD and ΔrodZ mutations that misregulate peripheral PG synthesis. Remarkably, the single MltG(Y488D) change suppresses the requirement for PBP2b, MreCD, RodZ and RodA. Structural modeling and comparisons, catalytic-site changes and an interspecies chimera indicate that pneumococcal MltG is the functional homologue of the recently reported MltG endo-lytic transglycosylase of Escherichia coli. Depletion of pneumococcal MltG or mltG(Y488D) increases sphericity of cells, and MltG localizes with peripheral PG synthesis proteins during division. Finally, growth of Δpbp1a ΔmltG or mltG(Y488D) mutants depends on induction of expression of the WalRK TCS regulon of PG hydrolases. These results fit a model in which MltG releases anchored PG glycan strands synthesized by PBP1a for crosslinking by a PBP2b:RodA complex in peripheral PG synthesis.
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Affiliation(s)
| | - Jiaqi J Zheng
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - Ariel N Magallon
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - John D Ryan
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - Rachel Yunck
- Department of Microbiology and Immunology, Harvard Medical School, Boston, MA, 02115, USA
| | - Britta E Rued
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - Thomas G Bernhardt
- Department of Microbiology and Immunology, Harvard Medical School, Boston, MA, 02115, USA
| | - Malcolm E Winkler
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
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157
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Fura JM, Pidgeon SE, Birabaharan M, Pires MM. Dipeptide-Based Metabolic Labeling of Bacterial Cells for Endogenous Antibody Recruitment. ACS Infect Dis 2016; 2:302-309. [PMID: 27294199 PMCID: PMC4898660 DOI: 10.1021/acsinfecdis.6b00007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Indexed: 02/06/2023]
Abstract
![]()
The number of antibiotic-resistant
bacterial infections has increased
dramatically over the past decade. To combat these pathogens, novel
antimicrobial strategies must be explored and developed. We previously
reported a strategy based on hapten-modified cell wall analogues to
induce recruitment of endogenous antibodies to bacterial cell surfaces.
Cell surface remodeling using unnatural single d-amino acid
cell wall analogues led to modification at the C-terminus of the peptidoglycan
stem peptide. During peptidoglycan processing, installed hapten-displaying
amino acids can be subsequently removed by cell wall enzymes. Herein,
we disclose a two-step dipeptide peptidoglycan remodeling strategy
aimed at introducing haptens at an alternative site within the stem
peptide to improve retention and diminish removal by cell wall enzymes.
Through this redesigned strategy, we determined size constraints of
peptidoglycan remodeling and applied these constraints to attain hapten–linker
conjugates that produced high levels of antibody recruitment to bacterial
cell surfaces.
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Affiliation(s)
- Jonathan M. Fura
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Sean E. Pidgeon
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Morgan Birabaharan
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Marcos M. Pires
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
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158
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Mutation of the murC and murB Genes Impairs Heterocyst Differentiation in Anabaena sp. Strain PCC 7120. J Bacteriol 2016; 198:1196-206. [PMID: 26811320 DOI: 10.1128/jb.01027-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 01/20/2016] [Indexed: 01/04/2023] Open
Abstract
UNLABELLED To stabilize cellular integrity in the face of environmental perturbations, most bacteria, including cyanobacteria, synthesize and maintain a strong, flexible, three-dimensional peptidoglycan lattice. Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium capable of differentiating morphologically distinct nitrogen-fixing heterocyst cells in a periodic pattern. While heterocyst development has been shown to require proper peptidoglycan remodeling, the role of peptidoglycan synthesis has remained unclear. Here we report the identification of two peptidoglycan synthesis genes, murC (alr5065) and murB (alr5066), as required for heterocyst development. The murC and murB genes are predicted to encode a UDP-N-acetylmuramate:L-alanine ligase and a UDP-N-acetylenolpyruvoylglucosamine reductase, respectively, and we confirm enzymatic function through complementation of Escherichia coli strains deficient for these enzymes. Cells depleted of either murC or murB expression failed to differentiate heterocysts under normally inducing conditions and displayed decreased filament integrity. To identify the stage(s) of development affected by murC or murB depletion, the spatial distribution of expression of the patterning marker gene, patS, was examined. Whereas murB depletion did not affect the pattern of patS expression, murC depletion led to aberrant expression of patS in all cells of the filament. Finally, expression of gfp controlled by the region of DNA immediately upstream of murC was enriched in differentiating cells and was repressed by the transcription factor NtcA. Collectively, the data in this work provide evidence for a direct link between peptidoglycan synthesis and the maintenance of a biological pattern in a multicellular organism. IMPORTANCE Multicellular organisms that differentiate specialized cells must regulate morphological changes such that both cellular integrity and the dissemination of developmental signals are preserved. Here we show that the multicellular bacterium Anabaena, which differentiates a periodic pattern of specialized heterocyst cells, requires peptidoglycan synthesis by the murine ligase genes murC (alr5065) and murB (alr5066) for maintenance of patterned gene expression, filament integrity, and overall development. This work highlights the significant influence that intracellular structure and intercellular connections can have on the execution of a developmental program.
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159
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Mahamad Maifiah MH, Cheah SE, Johnson MD, Han ML, Boyce JD, Thamlikitkul V, Forrest A, Kaye KS, Hertzog P, Purcell AW, Song J, Velkov T, Creek DJ, Li J. Global metabolic analyses identify key differences in metabolite levels between polymyxin-susceptible and polymyxin-resistant Acinetobacter baumannii. Sci Rep 2016; 6:22287. [PMID: 26924392 PMCID: PMC4770286 DOI: 10.1038/srep22287] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 02/11/2016] [Indexed: 02/07/2023] Open
Abstract
Multidrug-resistant Acinetobacter baumannii presents a global medical crisis and polymyxins are used as the last-line therapy. This study aimed to identify metabolic differences between polymyxin-susceptible and polymyxin-resistant A. baumannii using untargeted metabolomics. The metabolome of each A. baumannii strain was measured using liquid chromatography-mass spectrometry. Multivariate and univariate statistics and pathway analyses were employed to elucidate metabolic differences between the polymyxin-susceptible and -resistant A. baumannii strains. Significant differences were identified between the metabolic profiles of the polymyxin-susceptible and -resistant A. baumannii strains. The lipopolysaccharide (LPS) deficient, polymyxin-resistant 19606R showed perturbation in specific amino acid and carbohydrate metabolites, particularly pentose phosphate pathway (PPP) and tricarboxylic acid (TCA) cycle intermediates. Levels of nucleotides were lower in the LPS-deficient 19606R. Furthermore, 19606R exhibited a shift in its glycerophospholipid profile towards increased abundance of short-chain lipids compared to the parent polymyxin-susceptible ATCC 19606. In contrast, in a pair of clinical isolates 03-149.1 (polymyxin-susceptible) and 03-149.2 (polymyxin-resistant, due to modification of lipid A), minor metabolic differences were identified. Notably, peptidoglycan biosynthesis metabolites were significantly depleted in both of the aforementioned polymyxin-resistant strains. This is the first comparative untargeted metabolomics study to show substantial differences in the metabolic profiles of the polymyxin-susceptible and -resistant A. baumannii.
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Affiliation(s)
- Mohd Hafidz Mahamad Maifiah
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Soon-Ee Cheah
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Matthew D. Johnson
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Mei-Ling Han
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - John D. Boyce
- Department of Microbiology, Faculty of Medicine, Nursing & Health Sciences, Monash University, Clayton, VIC, 3800, Australia
| | - Visanu Thamlikitkul
- Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Alan Forrest
- UNC Eshelman School of Pharmacy, The University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7569, USA
| | - Keith S. Kaye
- Detroit Medical Centre and Wayne State University, University Health Centre, Detroit, MI, 48201, USA
| | - Paul Hertzog
- Hudson Institute of Medical Research, Clayton, VIC, 3168, Australia
- Faculty of Medicine, Nursing & Health Sciences, Monash University, Clayton, VIC, 3800, Australia
| | - Anthony W. Purcell
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Nursing & Health Sciences, Monash University, Clayton, VIC, 3800, Australia
| | - Jiangning Song
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Nursing & Health Sciences, Monash University, Clayton, VIC, 3800, Australia
| | - Tony Velkov
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Darren J. Creek
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Jian Li
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
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160
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Sandoz KM, Popham DL, Beare PA, Sturdevant DE, Hansen B, Nair V, Heinzen RA. Transcriptional Profiling of Coxiella burnetii Reveals Extensive Cell Wall Remodeling in the Small Cell Variant Developmental Form. PLoS One 2016; 11:e0149957. [PMID: 26909555 PMCID: PMC4766238 DOI: 10.1371/journal.pone.0149957] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 02/05/2016] [Indexed: 11/19/2022] Open
Abstract
A hallmark of Coxiella burnetii, the bacterial cause of human Q fever, is a biphasic developmental cycle that generates biologically, ultrastructurally, and compositionally distinct large cell variant (LCV) and small cell variant (SCV) forms. LCVs are replicating, exponential phase forms while SCVs are non-replicating, stationary phase forms. The SCV has several properties, such as a condensed nucleoid and an unusual cell envelope, suspected of conferring enhanced environmental stability. To identify genetic determinants of the LCV to SCV transition, we profiled the C. burnetii transcriptome at 3 (early LCV), 5 (late LCV), 7 (intermediate forms), 14 (early SCV), and 21 days (late SCV) post-infection of Vero epithelial cells. Relative to early LCV, genes downregulated in the SCV were primarily involved in intermediary metabolism. Upregulated SCV genes included those involved in oxidative stress responses, arginine acquisition, and cell wall remodeling. A striking transcriptional signature of the SCV was induction (>7-fold) of five genes encoding predicted L,D transpeptidases that catalyze nonclassical 3-3 peptide cross-links in peptidoglycan (PG), a modification that can influence several biological traits in bacteria. Accordingly, of cross-links identified, muropeptide analysis showed PG of SCV with 46% 3-3 cross-links as opposed to 16% 3-3 cross-links for LCV. Moreover, electron microscopy revealed SCV with an unusually dense cell wall/outer membrane complex as compared to LCV with its clearly distinguishable periplasm and inner and outer membranes. Collectively, these results indicate the SCV produces a unique transcriptome with a major component directed towards remodeling a PG layer that likely contributes to Coxiella's environmental resistance.
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Affiliation(s)
- Kelsi M. Sandoz
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - David L. Popham
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Paul A. Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Daniel E. Sturdevant
- Genomics Unit, Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Bryan Hansen
- Electron Microscopy Unit, Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Vinod Nair
- Electron Microscopy Unit, Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Robert A. Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
- * E-mail:
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161
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Pidgeon SE, Pires MM. Metabolic remodeling of bacterial surfaces via tetrazine ligations. Chem Commun (Camb) 2016; 51:10330-3. [PMID: 26027845 DOI: 10.1039/c5cc01693b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Bioorthogonal click ligations are extensively used for the introduction of functional groups in biological systems. Tetrazine ligations are attractive in that they are catalyst-free and display favorable kinetics. We describe the efficient remodeling of bacterial cell surfaces using unnatural d-amino acids derivatized with tetrazine ligation handles. The metabolic incorporation of these unnatural d-amino acids onto bacterial cell surfaces resulted in a site-selective installation of fluorophores.
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Affiliation(s)
- S E Pidgeon
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
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162
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Staying in Shape: the Impact of Cell Shape on Bacterial Survival in Diverse Environments. Microbiol Mol Biol Rev 2016; 80:187-203. [PMID: 26864431 DOI: 10.1128/mmbr.00031-15] [Citation(s) in RCA: 161] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Bacteria display an abundance of cellular forms and can change shape during their life cycle. Many plausible models regarding the functional significance of cell morphology have emerged. A greater understanding of the genetic programs underpinning morphological variation in diverse bacterial groups, combined with assays of bacteria under conditions that mimic their varied natural environments, from flowing freshwater streams to diverse human body sites, provides new opportunities to probe the functional significance of cell shape. Here we explore shape diversity among bacteria, at the levels of cell geometry, size, and surface appendages (both placement and number), as it relates to survival in diverse environments. Cell shape in most bacteria is determined by the cell wall. A major challenge in this field has been deconvoluting the effects of differences in the chemical properties of the cell wall and the resulting cell shape perturbations on observed fitness changes. Still, such studies have begun to reveal the selective pressures that drive the diverse forms (or cell wall compositions) observed in mammalian pathogens and bacteria more generally, including efficient adherence to biotic and abiotic surfaces, survival under low-nutrient or stressful conditions, evasion of mammalian complement deposition, efficient dispersal through mucous barriers and tissues, and efficient nutrient acquisition.
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163
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Chan YGY, Frankel MB, Missiakas D, Schneewind O. SagB Glucosaminidase Is a Determinant of Staphylococcus aureus Glycan Chain Length, Antibiotic Susceptibility, and Protein Secretion. J Bacteriol 2016; 198:1123-36. [PMID: 26811319 PMCID: PMC4800868 DOI: 10.1128/jb.00983-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 01/20/2016] [Indexed: 01/18/2023] Open
Abstract
UNLABELLED The envelope of Staphylococcus aureus is comprised of peptidoglycan and its attached secondary polymers, teichoic acid, capsular polysaccharide, and protein. Peptidoglycan synthesis involves polymerization of lipid II precursors into glycan strands that are cross-linked at wall peptides. It is not clear whether peptidoglycan structure is principally determined during polymerization or whether processive enzymes affect cell wall structure and function, for example, by generating conduits for protein secretion. We show here that S. aureus lacking SagB, a membrane-associated N-acetylglucosaminidase, displays growth and cell-morphological defects caused by the exaggerated length of peptidoglycan strands. SagB cleaves polymerized glycan strands to their physiological length and modulates antibiotic resistance in methicillin-resistant S. aureus (MRSA). Deletion of sagB perturbs protein trafficking into and across the envelope, conferring defects in cell wall anchoring and secretion, as well as aberrant excretion of cytoplasmic proteins. IMPORTANCE Staphylococcus aureus is thought to secrete proteins across the plasma membrane via the Sec pathway; however, protein transport across the cell wall envelope has heretofore not been studied. We report that S. aureus sagB mutants generate elongated peptidoglycan strands and display defects in protein secretion as well as aberrant excretion of cytoplasmic proteins. These results suggest that the thick peptidoglycan layer of staphylococci presents a barrier for protein secretion and that SagB appears to extend the Sec pathway across the cell wall envelope.
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Affiliation(s)
- Yvonne G Y Chan
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | - Matthew B Frankel
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | - Dominique Missiakas
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Argonne, Illinois, USA
| | - Olaf Schneewind
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Argonne, Illinois, USA
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Abstract
Nearly all bacteria contain a peptidoglycan cell wall. The peptidoglycan precursor molecule is LipidII, containing the basic peptidoglycan building block attached to a lipid. Although the suitability of LipidII as an antibacterial target has long been recognized, progress on elucidating the role(s) of LipidII in bacterial cell biology has been slow. The focus of this review is on exciting new developments, both with respect to antibacterials targeting LipidII as well as the emerging role of LipidII in organizing the membrane and cell wall synthesis. It appears that on both sides of the membrane, LipidII plays crucial roles in organizing cytoskeletal proteins and peptidoglycan synthesis machineries. Finally, the recent discovery of no less than three different categories of LipidII flippases will be discussed.
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Affiliation(s)
- Dirk-Jan Scheffers
- Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
- * E-mail:
| | - Menno B. Tol
- Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
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165
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Evaluation of an Immunochromatographic Assay for Rapid Detection of Penicillin-Binding Protein 2a in Human and Animal Staphylococcus intermedius Group, Staphylococcus lugdunensis, and Staphylococcus schleiferi Clinical Isolates. J Clin Microbiol 2015; 54:745-8. [PMID: 26677248 DOI: 10.1128/jcm.02869-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 12/04/2015] [Indexed: 12/31/2022] Open
Abstract
The performance of a rapid penicillin-binding protein 2a (PBP2a) detection assay, the Alere PBP2a culture colony test, was evaluated for identification of PBP2a-mediated beta-lactam resistance in human and animal clinical isolates of Staphylococcus intermedius group, Staphylococcus lugdunensis, and Staphylococcus schleiferi. The assay was sensitive and specific, with all PBP2a-negative and PBP2a-positive strains testing negative and positive, respectively.
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166
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Patin D, Turk S, Barreteau H, Mainardi JL, Arthur M, Gobec S, Mengin-Lecreulx D, Blanot D. Unusual substrate specificity of the peptidoglycan MurE ligase from Erysipelothrix rhusiopathiae. Biochimie 2015; 121:209-18. [PMID: 26700151 DOI: 10.1016/j.biochi.2015.12.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 12/06/2015] [Indexed: 01/23/2023]
Abstract
Erysipelothrix rhusiopathiae is a Gram-positive bacterium pathogenic to many species of birds and mammals, including humans. The main feature of its peptidoglycan is the presence of l-alanine at position 3 of the peptide stem. In the present work, we cloned the murE gene from E. rhusiopathiae and purified the corresponding protein as His6-tagged form. Enzymatic assays showed that E. rhusiopathiae MurE was indeed an l-alanine-adding enzyme. Surprisingly, it was also able, although to a lesser extent, to add meso-diaminopimelic acid, the amino acid found at position 3 in many Gram-negative bacteria, Bacilli and Mycobacteria. Sequence alignment of MurE enzymes from E. rhusiopathiae and Escherichia coli revealed that the DNPR motif that is characteristic of meso-diaminopimelate-adding enzymes was replaced by HDNR. The role of the latter motif in the interaction with l-alanine and meso-diaminopimelic acid was demonstrated by site-directed mutagenesis experiments and the construction of a homology model. The overexpression of the E. rhusiopathiae murE gene in E. coli resulted in the incorporation of l-alanine at position 3 of the peptide part of peptidoglycan.
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Affiliation(s)
- Delphine Patin
- Institut de Biologie Intégrative de la Cellule (I2BC), UMR 9198 CEA/CNRS/Université Paris-Sud, 91405 Orsay, France.
| | - Samo Turk
- Fakulteta za Farmacijo, Univerza v Ljubljani, Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Hélène Barreteau
- Institut de Biologie Intégrative de la Cellule (I2BC), UMR 9198 CEA/CNRS/Université Paris-Sud, 91405 Orsay, France
| | - Jean-Luc Mainardi
- Laboratoire de Recherche Moléculaire sur les Antibiotiques, Centre de Recherche des Cordeliers, Equipe 12, INSERM U1138, 75006 Paris, France; Université Pierre et Marie Curie - Paris 6, UMR S1138, 15 Rue de l'Ecole de Médecine, 75006 Paris, France; Université Paris-Descartes, Sorbonne Paris Cité, UMR S1138, 75006 Paris, France
| | - Michel Arthur
- Laboratoire de Recherche Moléculaire sur les Antibiotiques, Centre de Recherche des Cordeliers, Equipe 12, INSERM U1138, 75006 Paris, France; Université Pierre et Marie Curie - Paris 6, UMR S1138, 15 Rue de l'Ecole de Médecine, 75006 Paris, France; Université Paris-Descartes, Sorbonne Paris Cité, UMR S1138, 75006 Paris, France
| | - Stanislav Gobec
- Fakulteta za Farmacijo, Univerza v Ljubljani, Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Dominique Mengin-Lecreulx
- Institut de Biologie Intégrative de la Cellule (I2BC), UMR 9198 CEA/CNRS/Université Paris-Sud, 91405 Orsay, France
| | - Didier Blanot
- Institut de Biologie Intégrative de la Cellule (I2BC), UMR 9198 CEA/CNRS/Université Paris-Sud, 91405 Orsay, France
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167
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Sosič I, Anderluh M, Sova M, Gobec M, Mlinarič Raščan I, Derouaux A, Amoroso A, Terrak M, Breukink E, Gobec S. Structure-Activity Relationships of Novel Tryptamine-Based Inhibitors of Bacterial Transglycosylase. J Med Chem 2015; 58:9712-21. [PMID: 26588190 DOI: 10.1021/acs.jmedchem.5b01482] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Penicillin-binding proteins represent well-established, validated, and still very promising targets for the design and development of new antibacterial agents. The transglycosylase domain of penicillin-binding proteins is especially important, as it catalyzes polymerization of glycan chains, using the peptidoglycan precursor lipid II as a substrate. On the basis of the previous discovery of a noncovalent small-molecule inhibitor of transglycosylase activity, we systematically explored the structure-activity relationships of these tryptamine-based inhibitors. The main aim was to reduce the nonspecific cytotoxic properties of the initial hit compound and concurrently to retain the mode of its inhibition. A focused library of tryptamine-based compounds was synthesized, characterized, and evaluated biochemically. The results presented here show the successful reduction of the nonspecific cytotoxicity, and the retention of the inhibition of transglycosylase enzymatic activity, as well as the ability of these compounds to bind to lipid II and to have antibacterial actions.
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Affiliation(s)
- Izidor Sosič
- Faculty of Pharmacy, University of Ljubljana , Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Marko Anderluh
- Faculty of Pharmacy, University of Ljubljana , Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Matej Sova
- Faculty of Pharmacy, University of Ljubljana , Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Martina Gobec
- Faculty of Pharmacy, University of Ljubljana , Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Irena Mlinarič Raščan
- Faculty of Pharmacy, University of Ljubljana , Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Adeline Derouaux
- Centre d'Ingénierie des Protéines, Université de Liège , Allée de la Chimie, B6a, B-4000, Sart Tilman, Liège, Belgium
| | - Ana Amoroso
- Centre d'Ingénierie des Protéines, Université de Liège , Allée de la Chimie, B6a, B-4000, Sart Tilman, Liège, Belgium
| | - Mohammed Terrak
- Centre d'Ingénierie des Protéines, Université de Liège , Allée de la Chimie, B6a, B-4000, Sart Tilman, Liège, Belgium
| | - Eefjan Breukink
- Department Biochemistry of Membranes, Bijvoet Centre, Institute of Biomembranes, Utrecht University , Utrecht 3584 CH, The Netherlands
| | - Stanislav Gobec
- Faculty of Pharmacy, University of Ljubljana , Aškerčeva 7, 1000 Ljubljana, Slovenia
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168
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Teo ACK, Roper DI. Core Steps of Membrane-Bound Peptidoglycan Biosynthesis: Recent Advances, Insight and Opportunities. Antibiotics (Basel) 2015; 4:495-520. [PMID: 27025638 PMCID: PMC4790310 DOI: 10.3390/antibiotics4040495] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 10/03/2015] [Accepted: 10/26/2015] [Indexed: 11/16/2022] Open
Abstract
We are entering an era where the efficacy of current antibiotics is declining, due to the development and widespread dispersion of antibiotic resistance mechanisms. These factors highlight the need for novel antimicrobial discovery. A large number of antimicrobial natural products elicit their effect by directly targeting discrete areas of peptidoglycan metabolism. Many such natural products bind directly to the essential cell wall precursor Lipid II and its metabolites, i.e., preventing the utlisation of vital substrates by direct binding rather than inhibiting the metabolising enzymes themselves. Concurrently, there has been an increase in the knowledge surrounding the proteins essential to the metabolism of Lipid II at and across the cytoplasmic membrane. In this review, we draw these elements together and look to future antimicrobial opportunities in this area.
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Affiliation(s)
- Alvin C K Teo
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
| | - David I Roper
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
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169
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Rice DM, Romaniuk JAH, Cegelski L. Frequency-selective REDOR and spin-diffusion relays in uniformly labeled whole cells. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 72:132-9. [PMID: 26493462 PMCID: PMC4674448 DOI: 10.1016/j.ssnmr.2015.10.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/07/2015] [Accepted: 10/08/2015] [Indexed: 06/05/2023]
Abstract
Solid-state NMR is a powerful and non-perturbative method to measure and define chemical composition and architecture in bacterial cell walls, even in the context of whole cells. Most NMR studies on whole cells have used selectively labeled samples. Here, we introduce an NMR sequence relay using frequency-selective REDOR (fsREDOR) and spin diffusion elements to probe a unique amine contribution in uniformly (13)C- and (15)N-labeled Staphylococcus aureus whole cells that we attribute to the d-alanine of teichoic acid. In addition to the primary peptidoglycan structural scaffold, cell walls can contain significant amounts of teichoic acid that contribute to cell-wall function. When incorporated into teichoic acid, d-alanine is present as an ester, connected via its carbonyl to a ribitol carbon, and thus has a free amine. Teichoic acid d-Ala is removed during cell-wall isolations and can only be detected in the context of whole cells. The sequence presented here begins with fsREDOR and a chemical shift evolution period for 2D data acquisition, followed by DARR spin diffusion and then an additional fsREDOR period. fsREDOR elements were used for (13)C observation to avoid complications from (13)C-(13)C couplings due to uniform labeling and for (15)N dephasing to achieve selectivity in the nitrogens serving as dephasers. The results show that the selected amine nitrogen of interest is near to teichoic acid ribitol carbons and also the methyl group carbon associated with alanine. In addition, its carbonyl is not significantly dephased by amide nitrogens, consistent with the expected microenvironment around teichoic acid.
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Affiliation(s)
- David M Rice
- Stanford University, Department of Chemistry, 380 Roth Way, Stanford, CA 94305, USA
| | - Joseph A H Romaniuk
- Stanford University, Department of Chemistry, 380 Roth Way, Stanford, CA 94305, USA
| | - Lynette Cegelski
- Stanford University, Department of Chemistry, 380 Roth Way, Stanford, CA 94305, USA.
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170
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Dwivedi UN, Tiwari S, Singh P, Singh S, Awasthi M, Pandey VP. Treponema pallidum putative novel drug target identification and validation: rethinking syphilis therapeutics with plant-derived terpenoids. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2015; 19:104-14. [PMID: 25683888 DOI: 10.1089/omi.2014.0154] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Syphilis, a slow progressive and the third most common sexually transmitted disease found worldwide, is caused by a spirochete gram negative bacteria Treponema pallidum. Emergence of antibiotic resistant T. pallidum has led to a search for novel drugs and their targets. Subtractive genomics analyses of pathogen T. pallidum and host Homo sapiens resulted in identification of 126 proteins essential for survival and viability of the pathogen. Metabolic pathway analyses of these essential proteins led to discovery of nineteen proteins distributed among six metabolic pathways unique to T. pallidum. One hundred plant-derived terpenoids, as potential therapeutic molecules against T. pallidum, were screened for their drug likeness and ADMET (absorption, distribution, metabolism, and toxicity) properties. Subsequently the resulting nine terpenoids were docked with five unique T. pallidum targets through molecular modeling approaches. Out of five targets analyzed, D-alanine:D-alanine ligase was found to be the most promising target, while terpenoid salvicine was the most potent inhibitor. A comparison of the inhibitory potential of the best docked readily available natural compound, namely pomiferin (flavonoid) with that of the best docked terpenoid salvicine, revealed that salvicine was a more potent inhibitor than that of pomiferin. To the best of our knowledge, this is the first report of a terpenoid as a potential therapeutic molecule against T. pallidum with D-alanine:D-alanine ligase as a novel target. Further studies are warranted to evaluate and explore the potential clinical ramifications of these findings in relation to syphilis that has public health importance worldwide.
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Affiliation(s)
- Upendra N Dwivedi
- Department of Biochemistry, Centre of Excellence in Bioinformatics, Bioinformatics Infrastructure Facility, University of Lucknow , Lucknow, U.P., India
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171
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Soni V, Upadhayay S, Suryadevara P, Samla G, Singh A, Yogeeswari P, Sriram D, Nandicoori VK. Depletion of M. tuberculosis GlmU from Infected Murine Lungs Effects the Clearance of the Pathogen. PLoS Pathog 2015; 11:e1005235. [PMID: 26489015 PMCID: PMC4619583 DOI: 10.1371/journal.ppat.1005235] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 09/27/2015] [Indexed: 01/06/2023] Open
Abstract
M. tuberculosis N-acetyl-glucosamine-1-phosphate uridyltransferase (GlmUMtb) is a bi-functional enzyme engaged in the synthesis of two metabolic intermediates N-acetylglucosamine-1-phosphate (GlcNAc-1-P) and UDP-GlcNAc, catalyzed by the C- and N-terminal domains respectively. UDP-GlcNAc is a key metabolite essential for the synthesis of peptidoglycan, disaccharide linker, arabinogalactan and mycothiols. While glmUMtb was predicted to be an essential gene, till date the role of GlmUMtb in modulating the in vitro growth of Mtb or its role in survival of pathogen ex vivo / in vivo have not been deciphered. Here we present the results of a comprehensive study dissecting the role of GlmUMtb in arbitrating the survival of the pathogen both in vitro and in vivo. We find that absence of GlmUMtb leads to extensive perturbation of bacterial morphology and substantial reduction in cell wall thickness under normoxic as well as hypoxic conditions. Complementation studies show that the acetyl- and uridyl- transferase activities of GlmUMtb are independently essential for bacterial survival in vitro, and GlmUMtb is also found to be essential for mycobacterial survival in THP-1 cells as well as in guinea pigs. Depletion of GlmUMtb from infected murine lungs, four weeks post infection, led to significant reduction in the bacillary load. The administration of Oxa33, a novel oxazolidine derivative that specifically inhibits GlmUMtb, to infected mice resulted in significant decrease in the bacillary load. Thus our study establishes GlmUMtb as a strong candidate for intervention measures against established tuberculosis infections. The synthesis of the Mtb cell wall involves a cascade of reactions catalyzed by cytosolic and cell membrane-bound enzymes. The reaction catalyzed by GlmUMtb (an enzyme with acetyltransferase and uridyltransferase activities) generates UDP-GlcNAc, a central nucleotide-sugar building block of the cell wall. Apart from cell wall synthesis UDP-GlcNAc is an essential metabolite participating in other cellular processes including disaccharide linker and mycothiol biosynthesis. GlmUMtb shares very little sequence similarity with eukaryotic acetyltransferase and uridyltransferase enzymes. Many pathogens have alternative pathway(s) for foraging GlcNAc from the host. The present study was undertaken to see the effects of depleting GlmUMtb on pathogen survival in the host animal. We have generated a conditional gene replacement mutant of glmUMtb and find that depletion of GlmUMtb at any stage of bacterial growth or in mice infected with Mtb including a well-established infection, results in irreversible bacterial death due to perturbation of cell wall synthesis. We have developed a novel anti-GlmUMtb inhibitor (Oxa33), identified its binding site on GlmUMtb, and shown its specificity for GlmUMtb. The study demonstrates that GlmUMtb is a promising target for therapeutic intervention and Oxa33 can be pursued as a lead molecule.
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Affiliation(s)
- Vijay Soni
- National Institute of Immunology, New Delhi, India
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
| | | | - Priyanka Suryadevara
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
| | - Ganesh Samla
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
| | - Archana Singh
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Perumal Yogeeswari
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
| | - Dharmarajan Sriram
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
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172
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Mesleh MF, Rajaratnam P, Conrad M, Chandrasekaran V, Liu CM, Pandya BA, Hwang YS, Rye PT, Muldoon C, Becker B, Zuegg J, Meutermans W, Moy TI. Targeting Bacterial Cell Wall Peptidoglycan Synthesis by Inhibition of Glycosyltransferase Activity. Chem Biol Drug Des 2015; 87:190-9. [PMID: 26358369 DOI: 10.1111/cbdd.12662] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Revised: 08/20/2015] [Accepted: 08/27/2015] [Indexed: 11/25/2022]
Abstract
Synthesis of bacterial cell wall peptidoglycan requires glycosyltransferase enzymes that transfer the disaccharide-peptide from lipid II onto the growing glycan chain. The polymerization of the glycan chain precedes cross-linking by penicillin-binding proteins and is essential for growth for key bacterial pathogens. As such, bacterial cell wall glycosyltransferases are an attractive target for antibiotic drug discovery. However, significant challenges to the development of inhibitors for these targets include the development of suitable assays and chemical matter that is suited to the nature of the binding site. We developed glycosyltransferase enzymatic activity and binding assays using the natural products moenomycin and vancomycin as model inhibitors. In addition, we designed a library of disaccharide compounds based on the minimum moenomycin fragment with peptidoglycan glycosyltransferase inhibitory activity and based on a more drug-like and synthetically versatile disaccharide building block. A subset of these disaccharide compounds bound and inhibited the glycosyltransferase enzymes, and these compounds could serve as chemical entry points for antibiotic development.
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Affiliation(s)
- Michael F Mesleh
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
| | - Premraj Rajaratnam
- Alchemia Limited, 3 Hi-Tech Court, Eight Mile Plains, Brisbane Technology Park, Qld, 4113, Australia
| | - Mary Conrad
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
| | - Vasu Chandrasekaran
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
| | - Christopher M Liu
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
| | - Bhaumik A Pandya
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
| | - You Seok Hwang
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
| | - Peter T Rye
- Agilent Technologies, Inc., 11 Audubon Road, Wakefield, MA, 01880, USA
| | - Craig Muldoon
- Alchemia Limited, 3 Hi-Tech Court, Eight Mile Plains, Brisbane Technology Park, Qld, 4113, Australia
| | - Bernd Becker
- Alchemia Limited, 3 Hi-Tech Court, Eight Mile Plains, Brisbane Technology Park, Qld, 4113, Australia
| | - Johannes Zuegg
- Alchemia Limited, 3 Hi-Tech Court, Eight Mile Plains, Brisbane Technology Park, Qld, 4113, Australia
| | - Wim Meutermans
- Alchemia Limited, 3 Hi-Tech Court, Eight Mile Plains, Brisbane Technology Park, Qld, 4113, Australia
| | - Terence I Moy
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
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173
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Hou CW, Mohanan V, Zachara NE, Grimes CL. Identification and biological consequences of the O-GlcNAc modification of the human innate immune receptor, Nod2. Glycobiology 2015; 26:13-8. [PMID: 26369908 DOI: 10.1093/glycob/cwv076] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 09/04/2015] [Indexed: 12/18/2022] Open
Abstract
Nucleotide-binding oligomerization domain 2 (Nod2) is an intracellular receptor that can sense the bacterial peptidoglycan component, muramyl dipeptide. Upon activation, Nod2 induces the production of various inflammatory molecules such as cytokines and chemokines. Genetic linkage analysis identified and revealed three major mutations in Nod2 that are associated with the development of Crohn's disease. The objective of this study is to further characterize this protein by determining whether Nod2 is posttranslationally modified by O-N-acetylglucosamine (O-GlcNAc). O-GlcNAcylation is one type of posttranslational modification in which the O-GlcNAc transferase transfers GlcNAc from UDP-GlcNAc to selected serine and threonine residues of intracellular proteins. We found that wild-type Nod2 and a Nod2 Crohn's-associated variant are O-GlcNAcylated and this modification affects Nod2's ability to signal via the nuclear factor kappa B pathway.
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Affiliation(s)
| | - Vishnu Mohanan
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
| | - Natasha E Zachara
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Catherine Leimkuhler Grimes
- Department of Chemistry and Biochemistry Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
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174
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Minimal Peptidoglycan (PG) Turnover in Wild-Type and PG Hydrolase and Cell Division Mutants of Streptococcus pneumoniae D39 Growing Planktonically and in Host-Relevant Biofilms. J Bacteriol 2015; 197:3472-85. [PMID: 26303829 DOI: 10.1128/jb.00541-15] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 08/15/2015] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED We determined whether there is turnover of the peptidoglycan (PG) cell wall of the ovococcus bacterial pathogen Streptococcus pneumoniae (pneumococcus). Pulse-chase experiments on serotype 2 strain D39 radiolabeled with N-acetylglucosamine revealed little turnover and release of PG breakdown products during growth compared to published reports of PG turnover in Bacillus subtilis. PG dynamics were visualized directly by long-pulse-chase-new-labeling experiments using two colors of fluorescent d-amino acid (FDAA) probes to microscopically detect regions of new PG synthesis. Consistent with minimal PG turnover, hemispherical regions of stable "old" PG persisted in D39 and TIGR4 (serotype 4) cells grown in rich brain heart infusion broth, in D39 cells grown in chemically defined medium containing glucose or galactose as the carbon source, and in D39 cells grown as biofilms on a layer of fixed human epithelial cells. In contrast, B. subtilis exhibited rapid sidewall PG turnover in similar FDAA-labeling experiments. High-performance liquid chromatography (HPLC) analysis of biochemically released peptides from S. pneumoniae PG validated that FDAAs incorporated at low levels into pentamer PG peptides and did not change the overall composition of PG peptides. PG dynamics were also visualized in mutants lacking PG hydrolases that mediate PG remodeling, cell separation, or autolysis and in cells lacking the MapZ and DivIVA division regulators. In all cases, hemispheres of stable old PG were maintained. In PG hydrolase mutants exhibiting aberrant division plane placement, FDAA labeling revealed patches of inert PG at turns and bulge points. We conclude that growing S. pneumoniae cells exhibit minimal PG turnover compared to the PG turnover in rod-shaped cells. IMPORTANCE PG cell walls are unique to eubacteria, and many bacterial species turn over and recycle their PG during growth, stress, colonization, and virulence. Consequently, PG breakdown products serve as signals for bacteria to induce antibiotic resistance and as activators of innate immune responses. S. pneumoniae is a commensal bacterium that colonizes the human nasopharynx and opportunistically causes serious respiratory and invasive diseases. The results presented here demonstrate a distinct demarcation between regions of old PG and regions of new PG synthesis and minimal turnover of PG in S. pneumoniae cells growing in culture or in host-relevant biofilms. These findings suggest that S. pneumoniae minimizes the release of PG breakdown products by turnover, which may contribute to evasion of the innate immune system.
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175
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Fura JM, Pires MM. d-amino carboxamide-based recruitment of dinitrophenol antibodies to bacterial surfaces via peptidoglycan remodeling. Biopolymers 2015; 104:351-9. [DOI: 10.1002/bip.22618] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 01/12/2015] [Accepted: 01/14/2015] [Indexed: 12/13/2022]
Affiliation(s)
| | - Marcos M. Pires
- Department of Chemistry; Lehigh University; Bethlehem PA 18015
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176
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Šink R, Barreteau H, Patin D, Mengin-Lecreulx D, Gobec S, Blanot D. MurD enzymes: some recent developments. Biomol Concepts 2015; 4:539-56. [PMID: 25436755 DOI: 10.1515/bmc-2013-0024] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 09/10/2013] [Indexed: 12/21/2022] Open
Abstract
The synthesis of the peptide stem of bacterial peptidoglycan involves four enzymes, the Mur ligases (MurC, D, E and F). Among them, MurD is responsible for the ATP-dependent addition of d-glutamic acid to UDP-MurNAc-l-Ala, a reaction which involves acyl-phosphate and tetrahedral intermediates. Like most enzymes of peptidoglycan biosynthesis, MurD constitutes an attractive target for the design and synthesis of new antibacterial agents. Escherichia coli MurD has been the first Mur ligase for which the tridimensional (3D) structure was solved. Thereafter, several co-crystal structures with different ligands or inhibitors were released. In the present review, we will deal with work performed on substrate specificity, reaction mechanism and 3D structure of E. coli MurD. Then, a part of the review will be devoted to recent work on MurD orthologs from species other than E. coli and to cellular organization of Mur ligases and in vivo regulation of the MurD activity. Finally, we will review the different classes of MurD inhibitors that have been designed and assayed to date with the hope of obtaining new antibacterial compounds.
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177
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Abstract
Staphylococcus aureus is a major human and veterinary pathogen worldwide. Methicillin-resistant S. aureus (MRSA) poses a significant and enduring problem to the treatment of infection by such strains. Resistance is usually conferred by the acquisition of a nonnative gene encoding a penicillin-binding protein (PBP2a), with significantly lower affinity for β-lactams. This resistance allows cell-wall biosynthesis, the target of β-lactams, to continue even in the presence of typically inhibitory concentrations of antibiotic. PBP2a is encoded by the mecA gene, which is carried on a distinct mobile genetic element (SCCmec), the expression of which is controlled through a proteolytic signal transduction pathway comprising a sensor protein (MecR1) and a repressor (MecI). Many of the molecular and biochemical mechanisms underlying methicillin resistance in S. aureus have been elucidated, including regulatory events and the structure of key proteins. Here we review recent advances in this area.
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Affiliation(s)
- Sharon J. Peacock
- Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, United Kingdom
| | - Gavin K. Paterson
- School of Biological, Biomedical, and Environmental Sciences, University of Hull, Hull HU6 7RX, United Kingdom
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178
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Oh SY, Richter SG, Missiakas DM, Schneewind O. Glutamate Racemase Mutants of Bacillus anthracis. J Bacteriol 2015; 197:1854-61. [PMID: 25777674 PMCID: PMC4420906 DOI: 10.1128/jb.00070-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/06/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED D-Glutamate is an essential component of bacterial peptidoglycan and a building block of the poly-γ-D-glutamic acid (PDGA) capsule of Bacillus anthracis, the causative agent of anthrax. Earlier work suggested that two glutamate racemases, encoded by racE1 and racE2, are each essential for growth of B. anthracis, supplying D-glutamic acid for the synthesis of peptidoglycan and PDGA capsule. Earlier work could not explain, however, why two enzymes that catalyze the same reaction may be needed for bacterial growth. Here, we report that deletion of racE1 or racE2 did not prevent growth of B. anthracis Sterne (pXO1(+) pXO2(-)), the noncapsulating vaccine strain, or of B. anthracis Ames (pXO1(+) pXO2(+)), a fully virulent, capsulating isolate. While mutants with deletions in racE1 and racE2 were not viable, racE2 deletion delayed vegetative growth of B. anthracis following spore germination and caused aberrant cell shapes, phenotypes that were partially restored by exogenous D-glutamate. Deletion of racE1 or racE2 from B. anthracis Ames did not affect the production or stereochemical composition of the PDGA capsule. A model is presented whereby B. anthracis, similar to Bacillus subtilis, utilizes two functionally redundant racemase enzymes to synthesize D-glutamic acid for peptidoglycan synthesis. IMPORTANCE Glutamate racemases, enzymes that convert L-glutamate to D-glutamate, are targeted for antibiotic development. Glutamate racemase inhibitors may be useful for the treatment of bacterial infections such as anthrax, where the causative agent, B. anthracis, requires d-glutamate for the synthesis of peptidoglycan and poly-γ-D-glutamic acid (PDGA) capsule. Here we show that B. anthracis possesses two glutamate racemase genes that can be deleted without abolishing either bacterial growth or PDGA synthesis. These data indicate that drug candidates must inhibit both glutamate racemases, RacE1 and RacE2, in order to block B. anthracis growth and achieve therapeutic efficacy.
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Affiliation(s)
- So-Young Oh
- Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Lemont, Illinois, USA Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | - Stefan G Richter
- Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Lemont, Illinois, USA Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | - Dominique M Missiakas
- Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Lemont, Illinois, USA Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | - Olaf Schneewind
- Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Lemont, Illinois, USA Department of Microbiology, University of Chicago, Chicago, Illinois, USA
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179
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Jeske O, Schüler M, Schumann P, Schneider A, Boedeker C, Jogler M, Bollschweiler D, Rohde M, Mayer C, Engelhardt H, Spring S, Jogler C. Planctomycetes do possess a peptidoglycan cell wall. Nat Commun 2015; 6:7116. [PMID: 25964217 PMCID: PMC4432640 DOI: 10.1038/ncomms8116] [Citation(s) in RCA: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 04/07/2015] [Indexed: 11/28/2022] Open
Abstract
Most bacteria contain a peptidoglycan (PG) cell wall, which is critical for
maintenance of shape and important for cell division. In contrast, Planctomycetes
have been proposed to produce a proteinaceous cell wall devoid of PG. The apparent
absence of PG has been used as an argument for the putative planctomycetal ancestry
of all bacterial lineages. Here we show, employing multiple bioinformatic methods,
that planctomycetal genomes encode proteins required for PG synthesis. Furthermore,
we biochemically demonstrate the presence of the sugar and the peptide components of
PG in Planctomycetes. In addition, light and electron microscopic experiments reveal
planctomycetal PG sacculi that are susceptible to lysozyme treatment. Finally,
cryo-electron tomography demonstrates that Planctomycetes possess a typical PG cell
wall and that their cellular architecture is thus more similar to that of other
Gram-negative bacteria. Our findings shed new light on the cellular architecture and
cell division of the maverick Planctomycetes. Planctomycetes appear to differ from all other bacteria in their
cellular organization and their apparent lack of a peptidoglycan (PG) cell wall. Here
Jeske et al. show that Planctomycetes do possess a typical PG cell wall and that
their cellular architecture resembles that of Gram-negative bacteria.
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Affiliation(s)
- Olga Jeske
- Independent Junior Research Group Microbial Cell Biology and Genetics, Leibniz Institute-DSMZ, Inhoffenstraße 7b, Braunschweig 38124, Germany
| | - Margarete Schüler
- Department of Molecular Structural Biology, Max-Planck-Institute for Biochemistry, Am Klopferspitz 18, Martinsried 82152, Germany
| | - Peter Schumann
- Department of Microbiology, Leibniz Institute-DSMZ, Inhoffenstraße 7b, Braunschweig 38124, Germany
| | - Alexander Schneider
- Department of Microbiology and Biotechnology, University of Tübingen, Auf der Morgenstelle 28, Tübingen 72076, Germany
| | - Christian Boedeker
- Independent Junior Research Group Microbial Cell Biology and Genetics, Leibniz Institute-DSMZ, Inhoffenstraße 7b, Braunschweig 38124, Germany
| | - Mareike Jogler
- Independent Junior Research Group Microbial Cell Biology and Genetics, Leibniz Institute-DSMZ, Inhoffenstraße 7b, Braunschweig 38124, Germany
| | - Daniel Bollschweiler
- Department of Molecular Structural Biology, Max-Planck-Institute for Biochemistry, Am Klopferspitz 18, Martinsried 82152, Germany
| | - Manfred Rohde
- Research Group Molecular Mechanisms of Streptococci, Helmholtz Center for Infection Research GmbH, Inhoffenstraße 7, Braunschweig 38124, Germany
| | - Christoph Mayer
- Department of Microbiology and Biotechnology, University of Tübingen, Auf der Morgenstelle 28, Tübingen 72076, Germany
| | - Harald Engelhardt
- Department of Molecular Structural Biology, Max-Planck-Institute for Biochemistry, Am Klopferspitz 18, Martinsried 82152, Germany
| | - Stefan Spring
- Department of Microbiology, Leibniz Institute-DSMZ, Inhoffenstraße 7b, Braunschweig 38124, Germany
| | - Christian Jogler
- Independent Junior Research Group Microbial Cell Biology and Genetics, Leibniz Institute-DSMZ, Inhoffenstraße 7b, Braunschweig 38124, Germany
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180
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Schrempf H, Merling P. Extracellular Streptomyces lividans vesicles: composition, biogenesis and antimicrobial activity. Microb Biotechnol 2015; 8:644-58. [PMID: 25851532 PMCID: PMC4476819 DOI: 10.1111/1751-7915.12274] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 02/09/2015] [Accepted: 02/09/2015] [Indexed: 11/27/2022] Open
Abstract
We selected Streptomyces lividans to elucidate firstly the biogenesis and antimicrobial activities of extracellular vesicles that a filamentous and highly differentiated Gram-positive bacterium produces. Vesicle types range in diameter from 110 to 230 nm and 20 to 60 nm, respectively; they assemble to clusters, and contain lipids and phospholipids allowing their in situ imaging by specific fluorescent dyes. The presence of the identified secondary metabolite undecylprodigiosin provokes red fluorescence of a portion of the heterogeneous vesicle populations facilitating in vivo monitoring. Protuberances containing vesicles generate at tips, and alongside of substrate hyphae, and enumerate during late vegetative growth to droplet-like exudates. Owing to in situ imaging in the presence and absence of a green fluorescent vancomycin derivative, we conclude that protuberances comprising vesicles arise at sites with enhanced levels of peptidoglycan subunits [pentapeptide of lipid II (C55)-linked disaccharides], and reduced levels of polymerized and cross-linked peptidoglycan within hyphae. These sites correlate with enhanced levels of anionic phospholipids and lipids. Vesicles provoke pronounced damages of Aspergillus proliferans, Verticillium dahliae and induced clumping and distortion of Escherichia coli. These harmful effects are likely attributable to the action of the identified vesicular compounds including different enzyme types, components of signal transduction cascades and undecylprodigiosin. Based on our pioneering findings, we highlight novel clues with environmental implications and application potential.
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Affiliation(s)
- Hildgund Schrempf
- FB Biology/Chemistry, Applied Genetics of Microorganisms, University Osnabrück, Barbarastr. 13, D-49069, Osnabrück, Germany
| | - Philipp Merling
- FB Biology/Chemistry, Applied Genetics of Microorganisms, University Osnabrück, Barbarastr. 13, D-49069, Osnabrück, Germany
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181
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Bacterial killing via a type IV secretion system. Nat Commun 2015; 6:6453. [PMID: 25743609 DOI: 10.1038/ncomms7453] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 01/29/2015] [Indexed: 12/24/2022] Open
Abstract
Type IV secretion systems (T4SSs) are multiprotein complexes that transport effector proteins and protein-DNA complexes through bacterial membranes to the extracellular milieu or directly into the cytoplasm of other cells. Many bacteria of the family Xanthomonadaceae, which occupy diverse environmental niches, carry a T4SS with unknown function but with several characteristics that distinguishes it from other T4SSs. Here we show that the Xanthomonas citri T4SS provides these cells the capacity to kill other Gram-negative bacterial species in a contact-dependent manner. The secretion of one type IV bacterial effector protein is shown to require a conserved C-terminal domain and its bacteriolytic activity is neutralized by a cognate immunity protein whose 3D structure is similar to peptidoglycan hydrolase inhibitors. This is the first demonstration of the involvement of a T4SS in bacterial killing and points to this special class of T4SS as a mediator of both antagonistic and cooperative interbacterial interactions.
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182
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Samal HB, Prava J, Suar M, Mahapatra RK. Comparative genomics study of Salmonella Typhimurium LT2 for the identification of putative therapeutic candidates. J Theor Biol 2015; 369:67-79. [DOI: 10.1016/j.jtbi.2015.01.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 01/12/2015] [Accepted: 01/18/2015] [Indexed: 12/13/2022]
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183
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Abstract
Work over the past decade has highlighted the pivotal role of the actin-like MreB family of proteins in the determination and maintenance of rod cell shape in bacteria. Early images of MreB localization revealed long helical filaments, which were suggestive of a direct role in governing cell wall architecture. However, several more recent, higher-resolution studies have questioned the existence or importance of the helical structures. In this Opinion article, I navigate a path through these conflicting reports, revive the helix model and summarize the key questions that remain to be answered.
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Affiliation(s)
- Jeff Errington
- Centre for Bacterial Cell Biology, Medical Faculty, Newcastle University, Richardson Road, Newcastle-upon-Tyne NE2 4AX, UK
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184
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Kim SJ, Chang J, Singh M. Peptidoglycan architecture of Gram-positive bacteria by solid-state NMR. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1848:350-62. [PMID: 24915020 PMCID: PMC4258515 DOI: 10.1016/j.bbamem.2014.05.031] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 05/30/2014] [Accepted: 05/31/2014] [Indexed: 10/25/2022]
Abstract
Peptidoglycan is an essential component of cell wall in Gram-positive bacteria with unknown architecture. In this review, we summarize solid-state NMR approaches to address some of the unknowns in the Gram-positive bacteria peptidoglycan architecture: 1) peptidoglycan backbone conformation, 2) PG-lattice structure, 3) variations in the peptidoglycan architecture and composition, 4) the effects of peptidoglycan bridge-length on the peptidoglycan architecture in Fem mutants, 5) the orientation of glycan strands with respect to the membrane, and 6) the relationship between the peptidoglycan structure and the glycopeptide antibiotic mode of action. Solid-state NMR analyses of Staphylococcus aureus cell wall show that peptidoglycan chains are surprisingly ordered and densely packed. The peptidoglycan disaccharide backbone adopts 4-fold screw helical symmetry with the disaccharide unit periodicity of 40Å. Peptidoglycan lattice in the S. aureus cell wall is formed by cross-linked PG stems that have parallel orientations. The structural characterization of Fem-mutants of S. aureus with varying lengths of bridge structures suggests that the PG-bridge length is an important determining factor for the PG architecture.
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Affiliation(s)
- Sung Joon Kim
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76706, USA.
| | - James Chang
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76706, USA
| | - Manmilan Singh
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
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185
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Biology and Assembly of the Bacterial Envelope. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 883:41-76. [PMID: 26621461 DOI: 10.1007/978-3-319-23603-2_3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
All free-living bacterial cells are delimited and protected by an envelope of high complexity. This physiological barrier is essential for bacterial survival and assures multiple functions. The molecular assembly of the different envelope components into a functional structure represents a tremendous biological challenge and is of high interest for fundamental sciences. The study of bacterial envelope assembly has also been fostered by the need for novel classes of antibacterial agents to fight the problematic of bacterial resistance to antibiotics. This chapter focuses on the two most intensively studied classes of bacterial envelopes that belong to the phyla Firmicutes and Proteobacteria. The envelope of Firmicutes typically has one membrane and is defined as being monoderm whereas the envelope of Proteobacteria contains two distinct membranes and is referred to as being diderm. In this chapter, we will first discuss the multiple roles of the bacterial envelope and clarify the nomenclature used to describe the different types of envelopes. We will then define the architecture and composition of the envelopes of Firmicutes and Proteobacteria while outlining their similarities and differences. We will further cover the extensive progress made in the field of bacterial envelope assembly over the last decades, using Bacillus subtilis and Escherichia coli as model systems for the study of the monoderm and diderm bacterial envelopes, respectively. We will detail our current understanding of how molecular machines assure the secretion, insertion and folding of the envelope proteins as well as the assembly of the glycosidic components of the envelope. Finally, we will highlight the topics that are still under investigation, and that will surely lead to important discoveries in the near future.
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186
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Subfamily-specific adaptations in the structures of two penicillin-binding proteins from Mycobacterium tuberculosis. PLoS One 2014; 9:e116249. [PMID: 25551456 PMCID: PMC4281109 DOI: 10.1371/journal.pone.0116249] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Accepted: 12/05/2014] [Indexed: 11/19/2022] Open
Abstract
Beta-lactam antibiotics target penicillin-binding proteins including several enzyme classes essential for bacterial cell-wall homeostasis. To better understand the functional and inhibitor-binding specificities of penicillin-binding proteins from the pathogen, Mycobacterium tuberculosis, we carried out structural and phylogenetic analysis of two predicted D,D-carboxypeptidases, Rv2911 and Rv3330. Optimization of Rv2911 for crystallization using directed evolution and the GFP folding reporter method yielded a soluble quadruple mutant. Structures of optimized Rv2911 bound to phenylmethylsulfonyl fluoride and Rv3330 bound to meropenem show that, in contrast to the nonspecific inhibitor, meropenem forms an extended interaction with the enzyme along a conserved surface. Phylogenetic analysis shows that Rv2911 and Rv3330 belong to different clades that emerged in Actinobacteria and are not represented in model organisms such as Escherichia coli and Bacillus subtilis. Clade-specific adaptations allow these enzymes to fulfill distinct physiological roles despite strict conservation of core catalytic residues. The characteristic differences include potential protein-protein interaction surfaces and specificity-determining residues surrounding the catalytic site. Overall, these structural insights lay the groundwork to develop improved beta-lactam therapeutics for tuberculosis.
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187
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Qiao Y, Lebar MD, Schirner K, Schaefer K, Tsukamoto H, Kahne D, Walker S. Detection of lipid-linked peptidoglycan precursors by exploiting an unexpected transpeptidase reaction. J Am Chem Soc 2014; 136:14678-81. [PMID: 25291014 PMCID: PMC4210121 DOI: 10.1021/ja508147s] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
![]()
Penicillin-binding
proteins (PBPs) are involved in the synthesis
and remodeling of bacterial peptidoglycan (PG). Staphylococcus
aureus expresses four PBPs. Genetic studies in S.
aureus have implicated PBP4 in the formation of highly cross-linked
PG, but biochemical studies have not reached a consensus on its primary
enzymatic activity. Using synthetic Lipid II, we show here that PBP4
preferentially acts as a transpeptidase (TP) in vitro. Moreover, it is the PBP primarily responsible for incorporating
exogenous d-amino acids into cellular PG, implying that it
also has TP activity in vivo. Notably, PBP4 efficiently
exchanges d-amino acids not only into PG polymers but also
into the PG monomers Lipid I and Lipid II. This is the first demonstration
that any TP domain of a PBP can activate the PG monomer building blocks.
Exploiting the promiscuous TP activity of PBP4, we developed a simple,
highly sensitive assay to detect cellular pools of lipid-linked PG
precursors, which are of notoriously low abundance. This method, which
addresses a longstanding problem, is useful for assessing how genetic
and pharmacological perturbations affect precursor levels, and may
facilitate studies to elucidate antibiotic mechanism of action.
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Affiliation(s)
- Yuan Qiao
- Chemical Biology Program, Harvard University , Cambridge, Massachusetts 02138, United States
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188
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Discovery of chlamydial peptidoglycan reveals bacteria with murein sacculi but without FtsZ. Nat Commun 2014; 4:2856. [PMID: 24292151 PMCID: PMC3847603 DOI: 10.1038/ncomms3856] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 11/01/2013] [Indexed: 11/18/2022] Open
Abstract
Chlamydiae are important pathogens and symbionts, with unique cell biology features. They lack the cell-division protein FtsZ, which functions in maintaining cell shape and orchestrating cell division in almost all other bacteria. In addition, the existence of peptidoglycan (PG) in chlamydial cell envelopes has been highly controversial. Using electron cryotomography, mass spectrometry and fluorescent labeling dyes, here we show that some environmental chlamydiae have cell-wall sacculi consisting of an unusual PG type. Treatment with fosfomycin (a PG synthesis inhibitor) leads to lower infection rates and aberrant cell shapes, suggesting that PG synthesis is crucial for the chlamydial life cycle. Our findings demonstrate for the first time the presence of PG in a member of the Chlamydiae. They also present a unique example of a bacterium with a PG sacculus but without FtsZ, challenging the current hypothesis that it is the absence of a cell wall that renders FtsZ non-essential.
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189
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Tsui HCT, Boersma MJ, Vella SA, Kocaoglu O, Kuru E, Peceny JK, Carlson EE, VanNieuwenhze MS, Brun YV, Shaw SL, Winkler ME. Pbp2x localizes separately from Pbp2b and other peptidoglycan synthesis proteins during later stages of cell division of Streptococcus pneumoniae D39. Mol Microbiol 2014; 94:21-40. [PMID: 25099088 PMCID: PMC4209751 DOI: 10.1111/mmi.12745] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2014] [Indexed: 11/27/2022]
Abstract
The relative localization patterns of class B penicillin-binding proteins Pbp2x and Pbp2b were used as positional indicators of septal and peripheral (side-wall-like) peptidoglycan (PG) synthesis, respectively, in the mid-cell regions of Streptococcus pneumoniae cells at different stages of division. We confirm that Pbp2x and Pbp2b are essential in the strain D39 genetic background, which differs from that of laboratory strains. We show that Pbp2b, like Pbp2x and class A Pbp1a, follows a different localization pattern than FtsZ and remains at division septa after FtsZ reappears at the equators of daughter cells. Pulse-experiments with fluorescent D-amino acids (FDAAs) were performed in wild-type cells and in cells in which Pbp2x activity was preferentially inhibited by methicillin or Pbp2x amount was depleted. These experiments show that Pbp2x activity separates from that of other PBPs to the centres of constricting septa in mid-to-late divisional cells resolved by high-resolution 3D-SIM microscopy. Dual-protein and protein-fluorescent vancomycin 2D and 3D-SIM immunofluorescence microscopy (IFM) of cells at different division stages corroborate that Pbp2x separates to the centres of septa surrounded by an adjacent constricting ring containing Pbp2b, Pbp1a and regulators, StkP and MreC. The separate localization of Pbp2x suggests distinctive roles in completing septal PG synthesis and remodelling.
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Affiliation(s)
- Ho-Ching T. Tsui
- Department of Biology, Indiana University Bloomington,
Bloomington, IN 47405
| | - Michael J. Boersma
- Department of Biology, Indiana University Bloomington,
Bloomington, IN 47405
| | - Stephen A. Vella
- Department of Biology, Indiana University Bloomington,
Bloomington, IN 47405
| | - Ozden Kocaoglu
- Department of Molecular and Cellular Biochemistry, Indiana
University Bloomington, Bloomington, IN 47405
| | - Erkin Kuru
- Department of Molecular and Cellular Biochemistry, Indiana
University Bloomington, Bloomington, IN 47405
| | - Julia K. Peceny
- Department of Biology, Indiana University Bloomington,
Bloomington, IN 47405
| | - Erin E. Carlson
- Department of Molecular and Cellular Biochemistry, Indiana
University Bloomington, Bloomington, IN 47405
- Department of Chemistry, Indiana University Bloomington,
Bloomington, IN 47405
| | - Michael S. VanNieuwenhze
- Department of Molecular and Cellular Biochemistry, Indiana
University Bloomington, Bloomington, IN 47405
- Department of Chemistry, Indiana University Bloomington,
Bloomington, IN 47405
| | - Yves V. Brun
- Department of Biology, Indiana University Bloomington,
Bloomington, IN 47405
- Department of Molecular and Cellular Biochemistry, Indiana
University Bloomington, Bloomington, IN 47405
| | - Sidney L. Shaw
- Department of Biology, Indiana University Bloomington,
Bloomington, IN 47405
| | - Malcolm E. Winkler
- Department of Biology, Indiana University Bloomington,
Bloomington, IN 47405
- Department of Molecular and Cellular Biochemistry, Indiana
University Bloomington, Bloomington, IN 47405
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190
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Charge requirements of lipid II flippase activity in Escherichia coli. J Bacteriol 2014; 196:4111-9. [PMID: 25225268 DOI: 10.1128/jb.02172-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Peptidoglycan (PG) is an extracytoplasmic glycopeptide matrix essential for the integrity of the envelope of most bacteria. The PG building block is a disaccharide-pentapeptide that is synthesized as a lipid-linked precursor called lipid II. The translocation of the amphipathic lipid II across the cytoplasmic membrane is required for subsequent incorporation of the disaccharide-pentapeptide into PG. In Escherichia coli, the essential inner membrane protein MurJ is the lipid II flippase. Previous studies showed that 8 charged residues in the central cavity region of MurJ are crucial for function. Here, we completed the functional analysis of all 57 charged residues in MurJ and demonstrated that the respective positive or negative charge of the 8 aforementioned residues is required for proper MurJ function. Loss of the negative charge in one of these residues, D39, causes a severe defect in MurJ biogenesis; by engineering an intragenic suppressor mutation that restores MurJ biogenesis, we found that this charge is also essential for MurJ function. Because of the low level of homology between MurJ and putative orthologs from Gram-positive bacteria, we explored the conservation of these 8 charged residues in YtgP, a homolog from Streptococcus pyogenes. We found that only 3 positive charges are similarly positioned and essential in YtgP; YtgP possesses additional charged residues within its predicted cavity that are essential for function and conserved among Gram-positive bacteria. From these data, we hypothesize that some charged residues in the cavity region of MurJ homologs are required for interaction with lipid II and/or energy coupling during transport.
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191
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Jadhav A, Shanmugham B, Rajendiran A, Pan A. Unraveling novel broad-spectrum antibacterial targets in food and waterborne pathogens using comparative genomics and protein interaction network analysis. INFECTION GENETICS AND EVOLUTION 2014; 27:300-8. [PMID: 25128740 DOI: 10.1016/j.meegid.2014.08.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 07/31/2014] [Accepted: 08/07/2014] [Indexed: 02/04/2023]
Abstract
Food and waterborne diseases are a growing concern in terms of human morbidity and mortality worldwide, even in the 21st century, emphasizing the need for new therapeutic interventions for these diseases. The current study aims at prioritizing broad-spectrum antibacterial targets, present in multiple food and waterborne bacterial pathogens, through a comparative genomics strategy coupled with a protein interaction network analysis. The pathways unique and common to all the pathogens under study (viz., methane metabolism, d-alanine metabolism, peptidoglycan biosynthesis, bacterial secretion system, two-component system, C5-branched dibasic acid metabolism), identified by comparative metabolic pathway analysis, were considered for the analysis. The proteins/enzymes involved in these pathways were prioritized following host non-homology analysis, essentiality analysis, gut flora non-homology analysis and protein interaction network analysis. The analyses revealed a set of promising broad-spectrum antibacterial targets, present in multiple food and waterborne pathogens, which are essential for bacterial survival, non-homologous to host and gut flora, and functionally important in the metabolic network. The identified broad-spectrum candidates, namely, integral membrane protein/virulence factor (MviN), preprotein translocase subunits SecB and SecG, carbon storage regulator (CsrA), and nitrogen regulatory protein P-II 1 (GlnB), contributed by the peptidoglycan pathway, bacterial secretion systems and two-component systems, were also found to be present in a wide range of other disease-causing bacteria. Cytoplasmic proteins SecG, CsrA and GlnB were considered as drug targets, while membrane proteins MviN and SecB were classified as vaccine targets. The identified broad-spectrum targets can aid in the design and development of antibacterial agents not only against food and waterborne pathogens but also against other pathogens.
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Affiliation(s)
- Ankush Jadhav
- Centre for Bioinformatics, School of Life Sciences, Pondicherry University, Pondicherry 605014, India
| | - Buvaneswari Shanmugham
- Centre for Bioinformatics, School of Life Sciences, Pondicherry University, Pondicherry 605014, India
| | - Anjana Rajendiran
- Centre for Bioinformatics, School of Life Sciences, Pondicherry University, Pondicherry 605014, India
| | - Archana Pan
- Centre for Bioinformatics, School of Life Sciences, Pondicherry University, Pondicherry 605014, India.
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192
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Affiliation(s)
- Kevin D Young
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
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193
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Lebar MD, May JM, Meeske AJ, Leiman SA, Lupoli TJ, Tsukamoto H, Losick R, Rudner DZ, Walker S, Kahne D. Reconstitution of peptidoglycan cross-linking leads to improved fluorescent probes of cell wall synthesis. J Am Chem Soc 2014; 136:10874-7. [PMID: 25036369 PMCID: PMC4132960 DOI: 10.1021/ja505668f] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
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The
peptidoglycan precursor, Lipid II, produced in the model Gram-positive
bacterium Bacillus subtilis differs from Lipid II
found in Gram-negative bacteria such as Escherichia coli by a single amidation on the peptide side chain. How this difference
affects the cross-linking activity of penicillin-binding proteins
(PBPs) that assemble peptidoglycan in cells has not been investigated
because B. subtilis Lipid II was not previously available.
Here we report the synthesis of B. subtilis Lipid
II and its use by purified B. subtilis PBP1 and E. coli PBP1A. While enzymes from both organisms assembled B. subtilis Lipid II into glycan strands, only the B. subtilis enzyme cross-linked the strands. Furthermore, B. subtilis PBP1 catalyzed the exchange of both d-amino acids and d-amino carboxamides into nascent peptidoglycan,
but the E. coli enzyme only exchanged d-amino
acids. We exploited these observations to design a fluorescent d-amino carboxamide probe to label B. subtilis PG in vivo and found that this probe labels the cell wall dramatically
better than existing reagents.
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Affiliation(s)
- Matthew D Lebar
- Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
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194
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Hoyland CN, Aldridge C, Cleverley RM, Duchêne MC, Minasov G, Onopriyenko O, Sidiq K, Stogios PJ, Anderson WF, Daniel RA, Savchenko A, Vollmer W, Lewis RJ. Structure of the LdcB LD-carboxypeptidase reveals the molecular basis of peptidoglycan recognition. Structure 2014; 22:949-60. [PMID: 24909784 PMCID: PMC4087270 DOI: 10.1016/j.str.2014.04.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 04/24/2014] [Accepted: 04/29/2014] [Indexed: 01/30/2023]
Abstract
Peptidoglycan surrounds the bacterial cytoplasmic membrane to protect the cell against osmolysis. The biosynthesis of peptidoglycan, made of glycan strands crosslinked by short peptides, is the target of antibiotics like β-lactams and glycopeptides. Nascent peptidoglycan contains pentapeptides that are trimmed by carboxypeptidases to tetra- and tripeptides. The well-characterized DD-carboxypeptidases hydrolyze the terminal D-alanine from the stem pentapeptide to produce a tetrapeptide. However, few LD-carboxypeptidases that produce tripeptides have been identified, and nothing is known about substrate specificity in these enzymes. We report biochemical properties and crystal structures of the LD-carboxypeptidases LdcB from Streptococcus pneumoniae, Bacillus anthracis, and Bacillus subtilis. The enzymes are active against bacterial cell wall tetrapeptides and adopt a zinc-carboxypeptidase fold characteristic of the LAS superfamily. We have also solved the structure of S. pneumoniae LdcB with a product mimic, elucidating the residues essential for peptidoglycan recognition and the conformational changes that occur on ligand binding.
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Affiliation(s)
- Christopher N Hoyland
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Christine Aldridge
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4AX, UK
| | - Robert M Cleverley
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Marie-Clémence Duchêne
- Institut des Sciences de la Vie, Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium
| | - George Minasov
- Department of Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Center for Structural Genomics of Infectious Diseases (CSGID)
| | - Olena Onopriyenko
- Center for Structural Genomics of Infectious Diseases (CSGID); Department of Chemical Engineering and Applied Chemistry, 200 College Street, University of Toronto, Toronto, ON M5G 1L6, Canada
| | - Karzan Sidiq
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4AX, UK
| | - Peter J Stogios
- Center for Structural Genomics of Infectious Diseases (CSGID); Department of Chemical Engineering and Applied Chemistry, 200 College Street, University of Toronto, Toronto, ON M5G 1L6, Canada
| | - Wayne F Anderson
- Department of Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Center for Structural Genomics of Infectious Diseases (CSGID)
| | - Richard A Daniel
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4AX, UK
| | - Alexei Savchenko
- Center for Structural Genomics of Infectious Diseases (CSGID); Department of Chemical Engineering and Applied Chemistry, 200 College Street, University of Toronto, Toronto, ON M5G 1L6, Canada
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4AX, UK
| | - Richard J Lewis
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
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195
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Ollivaux C, Soyez D, Toullec JY. Biogenesis of d
-amino acid containing peptides/proteins: where, when and how? J Pept Sci 2014; 20:595-612. [DOI: 10.1002/psc.2637] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 03/13/2014] [Accepted: 03/18/2014] [Indexed: 12/12/2022]
Affiliation(s)
- Céline Ollivaux
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8227; Integrative Biology of Marine Models, Station Biologique de Roscoff; CS 90074, F-29688 Roscoff cedex France
- CNRS, UMR 8227; Integrative Biology of Marine Models, Station Biologique de Roscoff; CS 90074, F-29688 Roscoff cedex France
| | - Daniel Soyez
- Sorbonne Universités, UPMC Univ Paris 06, ER3; Biogenèse des signaux peptidiques; 7 Quai Saint Bernard F-75251 Paris cedex 05 France
- CNRS, ER3; Biogenèse des signaux peptidiques; 7 Quai Saint Bernard F-75251 Paris cedex 05 France
| | - Jean-Yves Toullec
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7144; Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff; CS 90074, F-29688 Roscoff cedex France
- CNRS, UMR 7144; Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff; CS 90074, F-29688 Roscoff cedex France
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196
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Braddick D, Sandhu S, Roper DI, Chappell MJ, Bugg TDH. Observation of the time-course for peptidoglycan lipid intermediate II polymerization by Staphylococcus aureus monofunctional transglycosylase. MICROBIOLOGY-SGM 2014; 160:1628-1636. [PMID: 24858082 DOI: 10.1099/mic.0.079442-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The polymerization of lipid intermediate II by the transglycosylase activity of penicillin-binding proteins (PBPs) represents an important target for antibacterial action, but limited methods are available for quantitative assay of this reaction, or screening potential inhibitors. A new labelling method for lipid II polymerization products using Sanger's reagent (fluoro-2,4-dinitrobenzene), followed by gel permeation HPLC analysis, has permitted the observation of intermediate polymerization products for Staphylococcus aureus monofunctional transglycosylase MGT. Peak formation is inhibited by 6 µM ramoplanin or enduracidin. Characterization by mass spectrometry indicates the formation of tetrasaccharide and octasaccharide intermediates, but not a hexasaccharide intermediate, suggesting a dimerization of a lipid-linked tetrasaccharide. Numerical modelling of the time-course data supports a kinetic model involving addition to lipid-linked tetrasaccharide of either lipid II or lipid-linked tetrasaccharide. Observation of free octasaccharide suggests that hydrolysis of the undecaprenyl diphosphate lipid carrier occurs at this stage in peptidoglycan transglycosylation.
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Affiliation(s)
- Darren Braddick
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - Sandeep Sandhu
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - David I Roper
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | | | - Timothy D H Bugg
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
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197
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Galley NF, O'Reilly AM, Roper DI. Prospects for novel inhibitors of peptidoglycan transglycosylases. Bioorg Chem 2014; 55:16-26. [PMID: 24924926 PMCID: PMC4126109 DOI: 10.1016/j.bioorg.2014.05.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 05/12/2014] [Accepted: 05/12/2014] [Indexed: 01/07/2023]
Abstract
We examine key aspects of transglycosylase inhibitor design. Low to high throughput assays suitable for transglycosylase drug discovery. Existing chemical start points for transglycosylase active site targeting.
The lack of novel antimicrobial drugs under development coupled with the increasing occurrence of resistance to existing antibiotics by community and hospital acquired infections is of grave concern. The targeting of biosynthesis of the peptidoglycan component of the bacterial cell wall has proven to be clinically valuable but relatively little therapeutic development has been directed towards the transglycosylase step of this process. Advances towards the isolation of new antimicrobials that target transglycosylase activity will rely on the development of the enzymological tools required to identify and characterise novel inhibitors of these enzymes. Therefore, in this article, we review the assay methods developed for transglycosylases and review recent novel chemical inhibitors discovered in relation to both the lipidic substrates and natural product inhibitors of the transglycosylase step.
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Affiliation(s)
- Nicola F Galley
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Amy M O'Reilly
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - David I Roper
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
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198
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Koßmehl S, Wöhlbrand L, Drüppel K, Feenders C, Blasius B, Rabus R. Subcellular protein localization (cell envelope) in Phaeobacter inhibens DSM 17395. Proteomics 2014; 13:2743-60. [PMID: 23907795 DOI: 10.1002/pmic.201300112] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 04/26/2013] [Accepted: 04/30/2013] [Indexed: 11/11/2022]
Abstract
Phaeobacter inhibens DSM 17395 is a metabolically versatile, secondary metabolite producing and surface colonizing member of the alphaproteobacterial Roseobacter clade. Proteins compartmentalized across the Gram-negative cell envelope are expected to be relevant for the habitat success of P. inhibens DSM 17395. Subcellular fractionation was followed by gel- or nano-LC-based separation of proteins and peptides, respectively. Subsequent MS-based identification of in total 1187 proteins allowed allocation to cytoplasm (303 proteins), cytoplasmic membrane (346), periplasm (325), outer membrane (76), and extracellular milieu (22). Multidimensional scaling was used to visualize the spreading of heuristically allocated proteins across the five different compartments. Experimentally inferred subcellular protein localization was compared with PSORTb prediction of protein secretion and membrane localization. Determined subcellular localizations of identified proteins were interpreted to reconstruct the functional traits of the different cell envelope compartments, in particular protein secretion and sorting, direct effector molecule transit, and cell envelope biogenesis. From a proteogenomic perspective, functional prediction of 74 genes (including 17 coding for proteins of hitherto unknown function) could be refined.
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Affiliation(s)
- Sebastian Koßmehl
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, Oldenburg, Germany
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199
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Peters K, Schweizer I, Beilharz K, Stahlmann C, Veening JW, Hakenbeck R, Denapaite D. Streptococcus pneumoniae PBP2x mid-cell localization requires the C-terminal PASTA domains and is essential for cell shape maintenance. Mol Microbiol 2014; 92:733-55. [DOI: 10.1111/mmi.12588] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Katharina Peters
- Department of Microbiology; University of Kaiserslautern; Paul-Ehrlich Straße 23 D-67663 Kaiserslautern Germany
| | - Inga Schweizer
- Department of Microbiology; University of Kaiserslautern; Paul-Ehrlich Straße 23 D-67663 Kaiserslautern Germany
| | - Katrin Beilharz
- Molecular Genetics Group; Groningen Biomolecular Sciences and Biotechnology Institute; Centre for Synthetic Biology; University of Groningen; Nijenborgh 7 9747 AG Groningen The Netherlands
| | - Christoph Stahlmann
- Department of Microbiology; University of Kaiserslautern; Paul-Ehrlich Straße 23 D-67663 Kaiserslautern Germany
| | - Jan-Willem Veening
- Molecular Genetics Group; Groningen Biomolecular Sciences and Biotechnology Institute; Centre for Synthetic Biology; University of Groningen; Nijenborgh 7 9747 AG Groningen The Netherlands
| | - Regine Hakenbeck
- Department of Microbiology; University of Kaiserslautern; Paul-Ehrlich Straße 23 D-67663 Kaiserslautern Germany
- Stiftung Alfried Krupp Kolleg Greifswald; D-17487 Greifswald Germany
| | - Dalia Denapaite
- Department of Microbiology; University of Kaiserslautern; Paul-Ehrlich Straße 23 D-67663 Kaiserslautern Germany
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200
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Abstract
Cell walls define a cell's shape in bacteria. The walls are rigid to resist large internal pressures, but remarkably plastic to adapt to a wide range of external forces and geometric constraints. Currently, it is unknown how bacteria maintain their shape. In this paper, we develop experimental and theoretical approaches and show that mechanical stresses regulate bacterial cell wall growth. By applying a precisely controllable hydrodynamic force to growing rod-shaped Escherichia coli and Bacillus subtilis cells, we demonstrate that the cells can exhibit two fundamentally different modes of deformation. The cells behave like elastic rods when subjected to transient forces, but deform plastically when significant cell wall synthesis occurs while the force is applied. The deformed cells always recover their shape. The experimental results are in quantitative agreement with the predictions of the theory of dislocation-mediated growth. In particular, we find that a single dimensionless parameter, which depends on a combination of independently measured physical properties of the cell, can describe the cell's responses under various experimental conditions. These findings provide insight into how living cells robustly maintain their shape under varying physical environments.
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