1
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Klupt S, Fam KT, Zhang X, Chodisetti PK, Mehmood A, Boyd T, Grotjahn D, Park D, Hang HC. Secreted antigen A peptidoglycan hydrolase is essential for Enterococcus faecium cell separation and priming of immune checkpoint inhibitor therapy. eLife 2024; 13:RP95297. [PMID: 38857064 PMCID: PMC11164530 DOI: 10.7554/elife.95297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2024] Open
Abstract
Enterococcus faecium is a microbiota species in humans that can modulate host immunity (Griffin and Hang, 2022), but has also acquired antibiotic resistance and is a major cause of hospital-associated infections (Van Tyne and Gilmore, 2014). Notably, diverse strains of E. faecium produce SagA, a highly conserved peptidoglycan hydrolase that is sufficient to promote intestinal immunity (Rangan et al., 2016; Pedicord et al., 2016; Kim et al., 2019) and immune checkpoint inhibitor antitumor activity (Griffin et al., 2021). However, the functions of SagA in E. faecium were unknown. Here, we report that deletion of sagA impaired E. faecium growth and resulted in bulged and clustered enterococci due to defective peptidoglycan cleavage and cell separation. Moreover, ΔsagA showed increased antibiotic sensitivity, yielded lower levels of active muropeptides, displayed reduced activation of the peptidoglycan pattern-recognition receptor NOD2, and failed to promote cancer immunotherapy. Importantly, the plasmid-based expression of SagA, but not its catalytically inactive mutant, restored ΔsagA growth, production of active muropeptides, and NOD2 activation. SagA is, therefore, essential for E. faecium growth, stress resistance, and activation of host immunity.
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Affiliation(s)
- Steven Klupt
- Department of Immunology and Microbiology, Scripps ResearchLa JollaUnited States
| | - Kyong Tkhe Fam
- Department of Immunology and Microbiology, Scripps ResearchLa JollaUnited States
| | - Xing Zhang
- Department of Immunology and Microbiology, Scripps ResearchLa JollaUnited States
| | | | - Abeera Mehmood
- Department of Immunology and Microbiology, Scripps ResearchLa JollaUnited States
| | - Tumara Boyd
- Department of Integrative Structural & Computational Biology, Scripps ResearchLa JollaUnited States
| | - Danielle Grotjahn
- Department of Integrative Structural & Computational Biology, Scripps ResearchLa JollaUnited States
| | - Donghyun Park
- Department of Integrative Structural & Computational Biology, Scripps ResearchLa JollaUnited States
| | - Howard C Hang
- Department of Immunology and Microbiology, Scripps ResearchLa JollaUnited States
- Department of Chemistry, Scripps ResearchLa JollaUnited States
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2
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Alcorlo M, Martínez-Caballero S, Li J, Sham LT, Luo M, Hermoso JA. Modulation of the lytic apparatus by the FtsEX complex within the bacterial division machinery. FEBS Lett 2024. [PMID: 38849310 DOI: 10.1002/1873-3468.14953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 05/24/2024] [Accepted: 05/28/2024] [Indexed: 06/09/2024]
Abstract
The FtsEX membrane complex constitutes an essential component of the ABC transporter superfamily, widely distributed among bacterial species. It governs peptidoglycan degradation for cell division, acting as a signal transmitter rather than a substrate transporter. Through the ATPase activity of FtsE, it facilitates signal transmission from the cytosol across the membrane to the periplasm, activating associated peptidoglycan hydrolases. This review concentrates on the latest structural advancements elucidating the architecture of the FtsEX complex and its interplay with lytic enzymes or regulatory counterparts. The revealed three-dimensional structures unveil a landscape wherein a precise array of intermolecular interactions, preserved across diverse bacterial species, afford meticulous spatial and temporal control over the cell division process.
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Affiliation(s)
- Martín Alcorlo
- Department of Crystallography and Structural Biology, Instituto de Química-Física "Blas Cabrera", Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Siseth Martínez-Caballero
- Department of Crystallography and Structural Biology, Instituto de Química-Física "Blas Cabrera", Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Jianwei Li
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
- Department of Biological Sciences, Center for Bioimaging Sciences, National University of Singapore, Singapore
| | - Lok-To Sham
- Infectious Diseases Translational Research Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Min Luo
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
- Department of Biological Sciences, Center for Bioimaging Sciences, National University of Singapore, Singapore
| | - Juan A Hermoso
- Department of Crystallography and Structural Biology, Instituto de Química-Física "Blas Cabrera", Consejo Superior de Investigaciones Científicas, Madrid, Spain
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3
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Meyer FM, Bramkamp M. Cell wall synthesizing complexes in Mycobacteriales. Curr Opin Microbiol 2024; 79:102478. [PMID: 38653035 DOI: 10.1016/j.mib.2024.102478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 04/04/2024] [Accepted: 04/07/2024] [Indexed: 04/25/2024]
Abstract
Members of the order Mycobacteriales are distinguished by a characteristic diderm cell envelope, setting them apart from other Actinobacteria species. In addition to the conventional peptidoglycan cell wall, these organisms feature an extra polysaccharide polymer composed of arabinose and galactose, termed arabinogalactan. The nonreducing ends of arabinose are covalently linked to mycolic acids (MAs), forming the immobile inner leaflet of the highly hydrophobic MA membrane. The contiguous outer leaflet of the MA membrane comprises trehalose mycolates and various lipid species. Similar to all actinobacteria, Mycobacteriales exhibit apical growth, facilitated by a polar localized elongasome complex. A septal cell envelope synthesis machinery, the divisome, builds instead of the cell wall structures during cytokinesis. In recent years, a growing body of knowledge has emerged regarding the cell wall synthesizing complexes of Mycobacteriales., focusing particularly on three model species: Corynebacterium glutamicum, Mycobacterium smegmatis, and Mycobacterium tuberculosis.
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Affiliation(s)
- Fabian M Meyer
- Institute for General Microbiology, Christian-Albrechts-University Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany
| | - Marc Bramkamp
- Institute for General Microbiology, Christian-Albrechts-University Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany.
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4
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Sundaram K, Vajravelu LK. Functional Analysis of Genes in Mycobacterium tuberculosis Action Against Autophagosome-Lysosome Fusion. Indian J Microbiol 2024; 64:367-375. [PMID: 39011011 PMCID: PMC11246336 DOI: 10.1007/s12088-024-01227-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 02/10/2024] [Indexed: 07/17/2024] Open
Abstract
Tuberculosis is a lethal disease that is one of the world's top ten death-associated infections in humans; Mycobacterium tuberculosis causes tuberculosis, and this bacterium is linked to the lysis of autophagolysosomal fusion action, a self-defense mechanism of its own. Thus, Cytoplasmic bacilli are sequestered by autophagy and transported to lysosomes to be inactivated to destroy intracellular bacteria. Besides this, a macrophage can limit intracellular Mycobacterium by using a type of autophagy, selective autophagy, a cell that marks undesirable ubiquitin existence in cytosolic cargo, acting as a "eat me" sensor in conjunction with cellular homeostasis. Mycobacterium tuberculosis genes of the PE_PGRS protein family inhibit autophagy, increase mycobacterial survival, and lead to latent tuberculosis infection associated with miRNAs. In addition, the family of autophagy-regulated (ATG) gene members are involved in autophagy and controls the initiation, expansion, maturation, and fusion of autophagosomes with lysosomes, among other signaling events that control autophagy flux and reduce inflammatory responses and forward to promote cellular proliferation. In line with the formation of caseous necrosis in macrophages by Mycobacterium tuberculosis and their action on the lysis of autophagosome fusion, it leads to latent tuberculosis infection. Therefore, we aimed to comprehensively analyses the autophagy and self-defense mechanism of Mycobacterium tuberculosis, which is to be gratified future research on novel therapeutic tools and diagnostic markers against tuberculosis.
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Affiliation(s)
- Karthikeyan Sundaram
- Department of Microbiology, SRM Medical College Hospital and Research Centre, Kattangulathur, Chennai, Tamilnadu 603203 India
| | - Leela Kagithakara Vajravelu
- Department of Microbiology, SRM Medical College Hospital and Research Centre, Kattangulathur, Chennai, Tamilnadu 603203 India
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5
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Chen Y, Gu J, Yang B, Yang L, Pang J, Luo Q, Li Y, Li D, Deng Z, Dong C, Dong H, Zhang Z. Structure and activity of the septal peptidoglycan hydrolysis machinery crucial for bacterial cell division. PLoS Biol 2024; 22:e3002628. [PMID: 38814940 PMCID: PMC11139282 DOI: 10.1371/journal.pbio.3002628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 04/14/2024] [Indexed: 06/01/2024] Open
Abstract
The peptidoglycan (PG) layer is a critical component of the bacterial cell wall and serves as an important target for antibiotics in both gram-negative and gram-positive bacteria. The hydrolysis of septal PG (sPG) is a crucial step of bacterial cell division, facilitated by FtsEX through an amidase activation system. In this study, we present the cryo-EM structures of Escherichia coli FtsEX and FtsEX-EnvC in the ATP-bound state at resolutions of 3.05 Å and 3.11 Å, respectively. Our PG degradation assays in E. coli reveal that the ATP-bound conformation of FtsEX activates sPG hydrolysis of EnvC-AmiB, whereas EnvC-AmiB alone exhibits autoinhibition. Structural analyses indicate that ATP binding induces conformational changes in FtsEX-EnvC, leading to significant differences from the apo state. Furthermore, PG degradation assays of AmiB mutants confirm that the regulation of AmiB by FtsEX-EnvC is achieved through the interaction between EnvC-AmiB. These findings not only provide structural insight into the mechanism of sPG hydrolysis and bacterial cell division, but also have implications for the development of novel therapeutics targeting drug-resistant bacteria.
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Affiliation(s)
- Yatian Chen
- Department of Clinical Laboratory, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Jiayue Gu
- Department of Clinical Laboratory, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Biao Yang
- Department of Clinical Laboratory, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Lili Yang
- State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Jie Pang
- State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Qinghua Luo
- State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Yirong Li
- Department of Clinical Laboratory, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Danyang Li
- The Cryo-EM Center, Core facility of Wuhan University, Wuhan University, Wuhan, China
| | - Zixin Deng
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Changjiang Dong
- Department of Clinical Laboratory, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Haohao Dong
- State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Zhengyu Zhang
- Department of Clinical Laboratory, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
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6
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Klupt S, Fam KT, Zhang X, Chodisetti PK, Mehmood A, Boyd T, Grotjahn D, Park D, Hang HC. Secreted antigen A peptidoglycan hydrolase is essential for Enterococcus faecium cell separation and priming of immune checkpoint inhibitor therapy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.19.567738. [PMID: 38014356 PMCID: PMC10680833 DOI: 10.1101/2023.11.19.567738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Enterococcus faecium is a microbiota species in humans that can modulate host immunity1, but has also acquired antibiotic resistance and is a major cause of hospital-associated infections2. Notably, diverse strains of E. faecium produce SagA, a highly conserved peptidoglycan hydrolase that is sufficient to promote intestinal immunity3-5 and immune checkpoint inhibitor antitumor activity6. However, the functions of SagA in E. faecium were unknown. Here we report that deletion of sagA impaired E. faecium growth and resulted in bulged and clustered enterococci due to defective peptidoglycan cleavage and cell separation. Moreover, ΔsagA showed increased antibiotic sensitivity, yielded lower levels of active muropeptides, displayed reduced activation of the peptidoglycan pattern-recognition receptor NOD2, and failed to promote cancer immunotherapy. Importantly, plasmid-based expression of SagA, but not its catalytically-inactive mutant, restored ΔsagA growth, production of active muropeptides and NOD2 activation. SagA is therefore essential for E. faecium growth, stress resistance and activation of host immunity.
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Affiliation(s)
- Steven Klupt
- Department of Immunology and Microbiology, Scripps Research, La Jolla, California 92037, United States
- Contributed equally
| | - Kyong Tkhe Fam
- Department of Immunology and Microbiology, Scripps Research, La Jolla, California 92037, United States
- Contributed equally
| | - Xing Zhang
- Department of Immunology and Microbiology, Scripps Research, La Jolla, California 92037, United States
- Contributed equally
| | - Pavan Kumar Chodisetti
- Department of Immunology and Microbiology, Scripps Research, La Jolla, California 92037, United States
| | - Abeera Mehmood
- Department of Immunology and Microbiology, Scripps Research, La Jolla, California 92037, United States
| | - Tumara Boyd
- Department of Integrative Structural & Computational Biology, Scripps Research, La Jolla, California 92037, United States
| | - Danielle Grotjahn
- Department of Integrative Structural & Computational Biology, Scripps Research, La Jolla, California 92037, United States
| | - Donghyun Park
- Department of Integrative Structural & Computational Biology, Scripps Research, La Jolla, California 92037, United States
| | - Howard C. Hang
- Department of Immunology and Microbiology, Scripps Research, La Jolla, California 92037, United States
- Department of Chemistry, Scripps Research, La Jolla, California 92037, United States
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7
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Samuels V, Mulelu AE, Ndlovu H, Marakalala MJ. Mycobacterial FtsEX-RipC interaction is required for normal growth and cell morphology in rifampicin and low ionic strength conditions. Microbiol Spectr 2024; 12:e0251523. [PMID: 38289931 PMCID: PMC10913748 DOI: 10.1128/spectrum.02515-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 12/23/2023] [Indexed: 02/01/2024] Open
Abstract
Tuberculosis, a lung disease caused by Mycobacterium tuberculosis (Mtb), remains a major global health problem ranking as the second leading cause of death from a single infectious agent. One of the major factors contributing toward Mtb's success as a pathogen is its unique cell wall and its ability to counteract various arms of the host's immune response. A recent genome-scale study profiled a list of candidate genes that are predicted to be essential for Mtb survival of host-mediated responses. One candidate was FtsEX, a protein complex composed of an ATP-binding domain, FtsE, and a transmembrane domain, FtsX. FtsEX functions through interaction with a periplasmic hydrolase, RipC. Homologs of FtsEX exist in other bacteria and have been linked with playing a key role in regulating peptidoglycan hydrolysis during cell elongation and division. Here, we report on Mycobacterium smegmatis, FtsE, FtsX, and RipC and their protective roles in stressful conditions. We demonstrate that the individual genes of FtsEX complex and RipC are not essential for survival in normal growth conditions but conditionally essential in low-salt media and antibiotic-treated media. Growth defects in these conditions were characterized by short and bulgy cells as well as elongated filamentous cells. Our results suggest that FtsE, FtsX, and RipC are required for both normal cell elongation and division and ultimately for survival in stressful conditions. IMPORTANCE Mycobacterial cell growth and division are coordinated with regulated peptidoglycan hydrolysis. Understanding cell wall gene complexes that govern normal cell division and elongation will aid in the development of tools to disarm the ability of mycobacteria to survive immune-like and antibiotic stresses. We combined genetic analyses and scanning electron microscopy to analyze morphological changes of mycobacterial FtsEX and RipC mutants in stressful conditions. We demonstrate that FtsE, FtsX, FtsEX, and RipC are conditionally required for the survival of Mycobacterium smegmatis during rifampicin treatment and in low-salt conditions. Growth defects in these conditions were characterized by short and bulgy cells as well as elongated filamentous cells. We also show that the FtsEX-RipC interaction is essential for the survival of M. smegmatis in rifampicin. Our results suggest that FtsE, FtsX, and RipC are required for normal cell wall regulation and ultimately for survival in stressful conditions.
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Affiliation(s)
- Veneshley Samuels
- Division of Medical Microbiology, Department of Pathology and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Andani E. Mulelu
- Division of Medical Biochemistry and Structural Biology, Department of Integrative Biomedical Sciences, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Hlumani Ndlovu
- Division of Chemical Systems Biology, Department of Integrative Biomedical Sciences and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Mohlopheni J. Marakalala
- Division of Immunology, Department of Pathology and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
- Africa Health Research Institute, Durban, KwaZulu-Natal, South Africa
- Division of Infection and Immunity, University College London, London, United Kingdom
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8
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Li J, Xu X, Shi J, Hermoso JA, Sham LT, Luo M. Regulation of the cell division hydrolase RipC by the FtsEX system in Mycobacterium tuberculosis. Nat Commun 2023; 14:7999. [PMID: 38044344 PMCID: PMC10694151 DOI: 10.1038/s41467-023-43770-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 11/17/2023] [Indexed: 12/05/2023] Open
Abstract
The FtsEX complex regulates, directly or via a protein mediator depending on bacterial genera, peptidoglycan degradation for cell division. In mycobacteria and Gram-positive bacteria, the FtsEX system directly activates peptidoglycan-hydrolases by a mechanism that remains unclear. Here we report our investigation of Mycobacterium tuberculosis FtsEX as a non-canonical regulator with high basal ATPase activity. The cryo-EM structures of the FtsEX system alone and in complex with RipC, as well as the ATP-activated state, unveil detailed information on the signal transduction mechanism, leading to the activation of RipC. Our findings indicate that RipC is recognized through a "Match and Fit" mechanism, resulting in an asymmetric rearrangement of the extracellular domains of FtsX and a unique inclined binding mode of RipC. This study provides insights into the molecular mechanisms of FtsEX and RipC regulation in the context of a critical human pathogen, guiding the design of drugs targeting peptidoglycan remodeling.
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Affiliation(s)
- Jianwei Li
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Xin Xu
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Jian Shi
- Center for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Juan A Hermoso
- Department of Crystallography and Structural Biology, Instituto de Química-Física "Blas Cabrera", Consejo Superior de Investigaciones Científicas, Madrid, Spain.
| | - Lok-To Sham
- Infectious Diseases Translational Research Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
| | - Min Luo
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Singapore.
- Center for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
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9
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Zhou Z, Wattiez R, Constant P, Marrakchi H, Soetaert K, Mathys V, Fontaine V, Zeng S. Telacebec Interferes with Virulence Lipid Biosynthesis Protein Expression and Sensitizes to Other Antibiotics. Microorganisms 2023; 11:2469. [PMID: 37894127 PMCID: PMC10609169 DOI: 10.3390/microorganisms11102469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 09/26/2023] [Accepted: 09/28/2023] [Indexed: 10/29/2023] Open
Abstract
Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a public health issue, particularly due to multi-drug-resistant Mtb. The bacillus is wrapped in a waxy envelope containing lipids acting as essential virulence factors, accounting for the natural antibiotic resistance of mycobacteria. Telacebec (previously known as Q203) is a promising new anti-TB agent inhibiting the cytochrome bc1 complex of a mycobacterial electron transport chain (ETC). Here, we show that the telacebec-challenged M. bovis BCG exhibited a reduced expression of proteins involved in the synthesis of phthiocerol dimycocerosates (PDIMs)/phenolic glycolipids (PGLs), lipid virulence factors associated with cell envelope impermeability. Consistently, telacebec, at concentrations lower than its MIC, downregulated the transcription of a PDIM/PGL-synthesizing operon, suggesting a metabolic vulnerability triggered by the drug. The drug was able to synergize on BCG with rifampicin or vancomycin, the latter being a drug exerting a marginal effect on PDIM-bearing bacilli. Telacebec at a concentration higher than its MIC had no detectable effect on cell wall PDIMs, as shown by TLC analysis, a finding potentially explained by the retaining of previously synthesized PDIMs due to the inhibition of growth. The study extends the potential of telacebec, demonstrating an effect on mycobacterial virulence lipids, allowing for the development of new anti-TB strategies.
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Affiliation(s)
- Zhiyu Zhou
- Microbiology, Bioorganic & Macromolecular Chemistry Research Unit, Faculté de Pharmacie, Université libre de Bruxelles (ULB), Boulevard du Triomphe, 1050 Brussels, Belgium
| | - Ruddy Wattiez
- Laboratory of Proteomics and Microbiology, Research Institute for Biosciences, University of Mons, Place du Parc 23, 7000 Mons, Belgium
| | - Patricia Constant
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III-Paul Sabatier (UT3), 31077 Toulouse, France
| | - Hedia Marrakchi
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III-Paul Sabatier (UT3), 31077 Toulouse, France
| | - Karine Soetaert
- National Reference Laboratory "Mycobacterium", Sciensano, 1180 Uccle, Belgium
| | - Vanessa Mathys
- National Reference Laboratory "Mycobacterium", Sciensano, 1180 Uccle, Belgium
| | - Véronique Fontaine
- Microbiology, Bioorganic & Macromolecular Chemistry Research Unit, Faculté de Pharmacie, Université libre de Bruxelles (ULB), Boulevard du Triomphe, 1050 Brussels, Belgium
| | - Sheng Zeng
- School of Nursing and Health, Nanfang College Guangzhou, Guangzhou 510970, China
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10
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Izquierdo-Martinez A, Billini M, Miguel-Ruano V, Hernández-Tamayo R, Richter P, Biboy J, Batuecas MT, Glatter T, Vollmer W, Graumann PL, Hermoso JA, Thanbichler M. DipM controls multiple autolysins and mediates a regulatory feedback loop promoting cell constriction in Caulobacter crescentus. Nat Commun 2023; 14:4095. [PMID: 37433794 DOI: 10.1038/s41467-023-39783-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 06/22/2023] [Indexed: 07/13/2023] Open
Abstract
Proteins with a catalytically inactive LytM-type endopeptidase domain are important regulators of cell wall-degrading enzymes in bacteria. Here, we study their representative DipM, a factor promoting cell division in Caulobacter crescentus. We show that the LytM domain of DipM interacts with multiple autolysins, including the soluble lytic transglycosylases SdpA and SdpB, the amidase AmiC and the putative carboxypeptidase CrbA, and stimulates the activities of SdpA and AmiC. Its crystal structure reveals a conserved groove, which is predicted to represent the docking site for autolysins by modeling studies. Mutations in this groove indeed abolish the function of DipM in vivo and its interaction with AmiC and SdpA in vitro. Notably, DipM and its targets SdpA and SdpB stimulate each other's recruitment to midcell, establishing a self-reinforcing cycle that gradually increases autolytic activity as cytokinesis progresses. DipM thus coordinates different peptidoglycan-remodeling pathways to ensure proper cell constriction and daughter cell separation.
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Affiliation(s)
- Adrian Izquierdo-Martinez
- Department of Biology, University of Marburg, Marburg, Germany
- Max Planck Fellow Group Bacterial Cell Biology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Maria Billini
- Department of Biology, University of Marburg, Marburg, Germany
| | - Vega Miguel-Ruano
- Department of Crystallography and Structural Biology, Instituto de Química-Física "Rocasolano", Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Rogelio Hernández-Tamayo
- Department of Chemistry, University of Marburg, Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Pia Richter
- Department of Biology, University of Marburg, Marburg, Germany
| | - Jacob Biboy
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - María T Batuecas
- Department of Crystallography and Structural Biology, Instituto de Química-Física "Rocasolano", Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Timo Glatter
- Mass Spectrometry and Proteomics Facility, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Peter L Graumann
- Department of Chemistry, University of Marburg, Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Juan A Hermoso
- Department of Crystallography and Structural Biology, Instituto de Química-Física "Rocasolano", Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Martin Thanbichler
- Department of Biology, University of Marburg, Marburg, Germany.
- Max Planck Fellow Group Bacterial Cell Biology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
- Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany.
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11
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Nakamoto R, Bamyaci S, Blomqvist K, Normark S, Henriques-Normark B, Sham LT. The divisome but not the elongasome organizes capsule synthesis in Streptococcus pneumoniae. Nat Commun 2023; 14:3170. [PMID: 37264013 DOI: 10.1038/s41467-023-38904-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 05/16/2023] [Indexed: 06/03/2023] Open
Abstract
The bacterial cell envelope consists of multiple layers, including the peptidoglycan cell wall, one or two membranes, and often an external layer composed of capsular polysaccharides (CPS) or other components. How the synthesis of all these layers is precisely coordinated remains unclear. Here, we identify a mechanism that coordinates the synthesis of CPS and peptidoglycan in Streptococcus pneumoniae. We show that CPS synthesis initiates from the division septum and propagates along the long axis of the cell, organized by the tyrosine kinase system CpsCD. CpsC and the rest of the CPS synthesis complex are recruited to the septum by proteins associated with the divisome (a complex involved in septal peptidoglycan synthesis) but not the elongasome (involved in peripheral peptidoglycan synthesis). Assembly of the CPS complex starts with CpsCD, then CpsA and CpsH, the glycosyltransferases, and finally CpsJ. Remarkably, targeting CpsC to the cell pole is sufficient to reposition CPS synthesis, leading to diplococci that lack CPS at the septum. We propose that septal CPS synthesis is important for chain formation and complement evasion, thereby promoting bacterial survival inside the host.
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Affiliation(s)
- Rei Nakamoto
- Infectious Diseases Translational Research Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117545, Singapore
| | - Sarp Bamyaci
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, SE-17177, Sweden
| | - Karin Blomqvist
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, SE-17177, Sweden
- Clinical Microbiology, Karolinska University Hospital Solna, SE-17176, Stockholm, Sweden
| | - Staffan Normark
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, SE-17177, Sweden
| | - Birgitta Henriques-Normark
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, SE-17177, Sweden
- Clinical Microbiology, Karolinska University Hospital Solna, SE-17176, Stockholm, Sweden
| | - Lok-To Sham
- Infectious Diseases Translational Research Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117545, Singapore.
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12
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Xu X, Li J, Chua WZ, Pages MA, Shi J, Hermoso JA, Bernhardt T, Sham LT, Luo M. Mechanistic insights into the regulation of cell wall hydrolysis by FtsEX and EnvC at the bacterial division site. Proc Natl Acad Sci U S A 2023; 120:e2301897120. [PMID: 37186861 PMCID: PMC10214136 DOI: 10.1073/pnas.2301897120] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 04/08/2023] [Indexed: 05/17/2023] Open
Abstract
The peptidoglycan (PG) cell wall produced by the bacterial division machinery is initially shared between the daughters and must be split to promote cell separation and complete division. In gram-negative bacteria, enzymes that cleave PG called amidases play major roles in the separation process. To prevent spurious cell wall cleavage that can lead to cell lysis, amidases like AmiB are autoinhibited by a regulatory helix. Autoinhibition is relieved at the division site by the activator EnvC, which is in turn regulated by the ATP-binding cassette (ABC) transporter-like complex called FtsEX. EnvC is also known to be autoinhibited by a regulatory helix (RH), but how its activity is modulated by FtsEX and the mechanism by which it activates the amidases have remained unclear. Here, we investigated this regulation by determining the structure of Pseudomonas aeruginosa FtsEX alone with or without bound ATP, in complex with EnvC, and in a FtsEX-EnvC-AmiB supercomplex. In combination with biochemical studies, the structures reveal that ATP binding is likely to activate FtsEX-EnvC and promote its association with AmiB. Furthermore, the AmiB activation mechanism is shown to involve a RH rearrangement. In the activated state of the complex, the inhibitory helix of EnvC is released, freeing it to associate with the RH of AmiB, which liberates its active site for PG cleavage. These regulatory helices are found in many EnvC proteins and amidases throughout gram-negative bacteria, suggesting that the activation mechanism is broadly conserved and a potential target for lysis-inducing antibiotics that misregulate the complex.
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Affiliation(s)
- Xin Xu
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore117543
| | - Jianwei Li
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore117543
| | - Wan-Zhen Chua
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545, Singapore
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545, Singapore
| | - Martin A. Pages
- Department of Crystallography and Structural Biology, Instituto de Química-Física “Rocasolano”, Consejo Superior de Investigaciones Científicas, Madrid28006, Spain
| | - Jian Shi
- Center for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore117543
| | - Juan A. Hermoso
- Department of Crystallography and Structural Biology, Instituto de Química-Física “Rocasolano”, Consejo Superior de Investigaciones Científicas, Madrid28006, Spain
| | - Thomas Bernhardt
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA02115
- HHMI, MA02115, Boston
| | - Lok-To Sham
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545, Singapore
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545, Singapore
| | - Min Luo
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore117543
- Center for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore117543
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13
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Griffin ME, Klupt S, Espinosa J, Hang HC. Peptidoglycan NlpC/P60 peptidases in bacterial physiology and host interactions. Cell Chem Biol 2023; 30:436-456. [PMID: 36417916 PMCID: PMC10192474 DOI: 10.1016/j.chembiol.2022.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 09/15/2022] [Accepted: 10/31/2022] [Indexed: 11/23/2022]
Abstract
The bacterial cell wall is composed of a highly crosslinked matrix of glycopeptide polymers known as peptidoglycan that dictates bacterial cell morphology and protects against environmental stresses. Regulation of peptidoglycan turnover is therefore crucial for bacterial survival and growth and is mediated by key protein complexes and enzyme families. Here, we review the prevalence, structure, and activity of NlpC/P60 peptidases, a family of peptidoglycan hydrolases that are crucial for cell wall turnover and division as well as interactions with antibiotics and different hosts. Understanding the molecular functions of NlpC/P60 peptidases should provide important insight into bacterial physiology, their interactions with different kingdoms of life, and the development of new therapeutic approaches.
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Affiliation(s)
- Matthew E Griffin
- Department of Immunology and Microbiology, Scripps Research, La Jolla, CA 92037, USA
| | - Steven Klupt
- Department of Immunology and Microbiology, Scripps Research, La Jolla, CA 92037, USA
| | - Juliel Espinosa
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, NY 10065, USA
| | - Howard C Hang
- Department of Immunology and Microbiology, Scripps Research, La Jolla, CA 92037, USA; Department of Chemistry, Scripps Research, La Jolla, CA 92037, USA.
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14
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Brogan AP, Rudner DZ. Regulation of peptidoglycan hydrolases: localization, abundance, and activity. Curr Opin Microbiol 2023; 72:102279. [PMID: 36812681 PMCID: PMC10031507 DOI: 10.1016/j.mib.2023.102279] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 02/22/2023]
Abstract
Most bacteria are surrounded by a cell wall composed of peptidoglycan (PG) that specifies shape and protects the cell from osmotic rupture. Growth, division, and morphogenesis are intimately linked to the synthesis of this exoskeleton but also its hydrolysis. The enzymes that cleave the PG meshwork require careful control to prevent aberrant hydrolysis and loss of envelope integrity. Bacteria employ diverse mechanisms to control the activity, localization, and abundance of these potentially autolytic enzymes. Here, we discuss four examples of how cells integrate these control mechanisms to finely tune cell wall hydrolysis. We highlight recent advances and exciting avenues for future investigation.
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Affiliation(s)
- Anna P Brogan
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - David Z Rudner
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA.
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15
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Fieweger RA, Wilburn KM, Montague CR, Roszkowski EK, Kelly CM, Southard TL, Sondermann H, Nazarova EV, VanderVen BC. MceG stabilizes the Mce1 and Mce4 transporters in Mycobacterium tuberculosis. J Biol Chem 2023; 299:102910. [PMID: 36642182 PMCID: PMC9947336 DOI: 10.1016/j.jbc.2023.102910] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 12/28/2022] [Accepted: 12/29/2022] [Indexed: 01/15/2023] Open
Abstract
Lipids are important nutrients for Mycobacterium tuberculosis (Mtb) to support bacterial survival in mammalian tissues and host cells. Fatty acids and cholesterol are imported across the Mtb cell wall via the dedicated Mce1 and Mce4 transporters, respectively. It is thought that the Mce1 and Mce4 transporters are comprised of subunits that confer substrate specificity and proteins that couple lipid transport to ATP hydrolysis, similar to other bacterial ABC transporters. However, unlike canonical bacterial ABC transporters, Mce1 and Mce4 appear to share a single ATPase, MceG. Previously, it was established that Mce1 and Mce4 are destabilized when key transporter subunits are rendered nonfunctional; therefore, we investigated here the role of MceG in Mce1 and Mce4 protein stability. We determined that key residues in the Walker B domain of MceG are required for the Mce1- and Mce4-mediated transport of fatty acids and cholesterol. Previously, it has been established that Mce1 and Mce4 are destabilized and/or degraded when key transporter subunits are rendered nonfunctional, thus we investigated a role for MceG in stabilizing Mce1 and Mce4. Using an unbiased quantitative proteomic approach, we demonstrate that Mce1 and Mce4 proteins are specifically degraded in mutants lacking MceG. Furthermore, bacteria expressing Walker B mutant variants of MceG failed to stabilize Mce1 and Mce4, and we show that deleting MceG impacts the fitness of Mtb in the lungs of mice. Thus, we conclude that MceG represents an enzymatic weakness that can be potentially leveraged to disable and destabilize both the Mce1 and Mce4 transporters in Mtb.
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Affiliation(s)
- Rachael A Fieweger
- Microbiology & Immunology, College of Veterinary Medicine, Cornell University, Ithaca New York, USA
| | - Kaley M Wilburn
- Microbiology & Immunology, College of Veterinary Medicine, Cornell University, Ithaca New York, USA
| | - Christine R Montague
- Microbiology & Immunology, College of Veterinary Medicine, Cornell University, Ithaca New York, USA
| | - Emma K Roszkowski
- Microbiology & Immunology, College of Veterinary Medicine, Cornell University, Ithaca New York, USA
| | - Carolyn M Kelly
- Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca New York, USA
| | - Teresa L Southard
- Biomedical Sciences; College of Veterinary Medicine, Cornell University, Ithaca New York, USA
| | - Holger Sondermann
- Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca New York, USA
| | - Evgeniya V Nazarova
- Microbiology & Immunology, College of Veterinary Medicine, Cornell University, Ithaca New York, USA
| | - Brian C VanderVen
- Microbiology & Immunology, College of Veterinary Medicine, Cornell University, Ithaca New York, USA.
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16
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FtsEX-independent control of RipA-mediated cell separation in Corynebacteriales. Proc Natl Acad Sci U S A 2022; 119:e2214599119. [PMID: 36469781 PMCID: PMC9897464 DOI: 10.1073/pnas.2214599119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The bacterial cell wall is a multi-layered mesh, whose major component is peptidoglycan (PG), a sugar polymer cross-linked by short peptide stems. During cell division, a careful balance of PG synthesis and degradation, precisely coordinated both in time and space, is necessary to prevent uncontrolled destruction of the cell wall. In Corynebacteriales, the D,L endopeptidase RipA has emerged as a major PG hydrolase for cell separation, and RipA defaults have major implications for virulence of the human pathogens Mycobacterium tuberculosis and Corynebacterium diphtheriae. However, the precise mechanisms by which RipA mediates cell separation remain elusive. Here we report phylogenetic, biochemical, and structural analysis of the Corynebacterium glutamicum homologue of RipA, Cg1735. The crystal structures of full-length Cg1735 in two different crystal forms revealed the C-terminal NlpC/P60 catalytic domain obtruded by its N-terminal conserved coiled-coil domain, which locks the enzyme in an autoinhibited state. We show that this autoinhibition is relieved by the extracellular core domain of the transmembrane septal protein Cg1604. The crystal structure of Cg1604 revealed a (β/α) protein with an overall topology similar to that of receiver domains from response regulator proteins. The atomic model of the Cg1735-Cg1604 complex, based on bioinformatical and mutational analysis, indicates that a conserved, distal-membrane helical insertion in Cg1604 is responsible for Cg1735 activation. The reported data provide important insights into how intracellular cell division signal(s), yet to be identified, control PG hydrolysis during RipA-mediated cell separation in Corynebacteriales.
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17
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Metal cofactor stabilization by a partner protein is a widespread strategy employed for amidase activation. Proc Natl Acad Sci U S A 2022; 119:e2201141119. [PMID: 35733252 PMCID: PMC9245657 DOI: 10.1073/pnas.2201141119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Construction and remodeling of the bacterial peptidoglycan (PG) cell wall must be carefully coordinated with cell growth and division. Central to cell wall construction are hydrolases that cleave bonds in peptidoglycan. These enzymes also represent potential new antibiotic targets. One such hydrolase, the amidase LytH in Staphylococcus aureus, acts to remove stem peptides from PG, controlling where substrates are available for insertion of new PG strands and consequently regulating cell size. When it is absent, cells grow excessively large and have division defects. For activity, LytH requires a protein partner, ActH, that consists of an intracellular domain, a large rhomboid protease domain, and three extracellular tetratricopeptide repeats (TPRs). Here, we demonstrate that the amidase-activating function of ActH is entirely contained in its extracellular TPRs. We show that ActH binding stabilizes metals in the LytH active site and that LytH metal binding in turn is needed for stable complexation with ActH. We further present a structure of a complex of the extracellular domains of LytH and ActH. Our findings suggest that metal cofactor stabilization is a general strategy used by amidase activators and that ActH houses multiple functions within a single protein.
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18
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Alcorlo M, Martínez-Caballero S, Molina R, Hermoso JA. Regulation of Lytic Machineries by the FtsEX Complex in the Bacterial Divisome. Subcell Biochem 2022; 99:285-315. [PMID: 36151380 DOI: 10.1007/978-3-031-00793-4_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The essential membrane complex FtsE/FtsX (FtsEX), belonging to the ABC transporter superfamily and widespread among bacteria, plays a relevant function in some crucial cell wall remodeling processes such as cell division, elongation, or sporulation. FtsEX plays a double role by recruiting proteins to the divisome apparatus and by regulating lytic activity of the cell wall hydrolases required for daughter cell separation. Interestingly, FtsEX does not act as a transporter but uses the ATPase activity of FtsE to mechanically transmit a signal from the cytosol, through the membrane, to the periplasm that activates the attached hydrolases. While the complete molecular details of such mechanism are not yet known, evidence has been recently reported that clarify essential aspects of this complex system. In this chapter we will present recent structural advances on this topic. The three-dimensional structure of FtsE, FtsX, and some of the lytic enzymes or their cognate regulators revealed an unexpected scenario in which a delicate set of intermolecular interactions, conserved among different bacterial genera, could be at the core of this regulatory mechanism providing exquisite control in both space and time of this central process to assist bacterial survival.
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Affiliation(s)
- Martín Alcorlo
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry "Rocasolano", CSIC, Madrid, Spain
| | - Siseth Martínez-Caballero
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry "Rocasolano", CSIC, Madrid, Spain
- Department of Chemistry of Biomacromolecules, Universidade Nacional Autonoma de Mexico, Ciudad de México, Mexico
| | - Rafael Molina
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry "Rocasolano", CSIC, Madrid, Spain
| | - Juan A Hermoso
- Department of Crystallography and Structural Biology, Institute of Physical Chemistry "Rocasolano", CSIC, Madrid, Spain.
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19
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Wysocka A, Jagielska E, Łężniak Ł, Sabała I. Two New M23 Peptidoglycan Hydrolases With Distinct Net Charge. Front Microbiol 2021; 12:719689. [PMID: 34630350 PMCID: PMC8498115 DOI: 10.3389/fmicb.2021.719689] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 08/16/2021] [Indexed: 11/13/2022] Open
Abstract
Bacterial peptidoglycan hydrolases play an essential role in cell wall metabolism during bacterial growth, division, and elongation (autolysins) or in the elimination of closely related species from the same ecological niche (bacteriocins). Most studies concerning the peptidoglycan hydrolases present in Gram-positive bacteria have focused on clinically relevant Staphylococcus aureus or the model organism Bacillus subtilis, while knowledge relating to other species remains limited. Here, we report two new peptidoglycan hydrolases from the M23 family of metallopeptidases derived from the same staphylococcal species, Staphylococcus pettenkoferi. They share modular architecture, significant sequence identity (60%), catalytic and binding residue conservation, and similar modes of activation, but differ in gene distribution, putative biological role, and, strikingly, in their isoelectric points (pIs). One of the peptides has a high pI, similar to that reported for all M23 peptidases evaluated to date, whereas the other displays a low pI, a unique feature among M23 peptidases. Consequently, we named them SpM23_B (Staphylococcus pettenkoferi M23 "Basic") and SpM23_A (Staphylococcus pettenkoferi M23 "Acidic"). Using genetic and biochemical approaches, we have characterized these two novel lytic enzymes, both in vitro and in their physiological context. Our study presents a detailed characterization of two novel and clearly distinct peptidoglycan hydrolases to understand their role in bacterial physiology.
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Affiliation(s)
- Alicja Wysocka
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Elżbieta Jagielska
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Łukasz Łężniak
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Izabela Sabała
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
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20
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Abstract
Most bacteria are surrounded by a peptidoglycan cell wall that defines their shape and protects them from osmotic lysis. The expansion and division of this structure therefore plays an integral role in bacterial growth and division. Additionally, the biogenesis of the peptidoglycan layer is the target of many of our most effective antibiotics. Thus, a better understanding of how the cell wall is built will enable the development of new therapies to combat the rise of drug-resistant bacterial infections. This review covers recent advances in defining the mechanisms involved in assembling the peptidoglycan layer with an emphasis on discoveries related to the function and regulation of the cell elongation and division machineries in the model organisms Escherichia coli and Bacillus subtilis. Expected final online publication date for the Annual Review of Microbiology, Volume 75 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Patricia D A Rohs
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA; .,Current affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Thomas G Bernhardt
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA; .,Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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21
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Alav I, Kobylka J, Kuth MS, Pos KM, Picard M, Blair JMA, Bavro VN. Structure, Assembly, and Function of Tripartite Efflux and Type 1 Secretion Systems in Gram-Negative Bacteria. Chem Rev 2021; 121:5479-5596. [PMID: 33909410 PMCID: PMC8277102 DOI: 10.1021/acs.chemrev.1c00055] [Citation(s) in RCA: 99] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Indexed: 12/11/2022]
Abstract
Tripartite efflux pumps and the related type 1 secretion systems (T1SSs) in Gram-negative organisms are diverse in function, energization, and structural organization. They form continuous conduits spanning both the inner and the outer membrane and are composed of three principal components-the energized inner membrane transporters (belonging to ABC, RND, and MFS families), the outer membrane factor channel-like proteins, and linking the two, the periplasmic adaptor proteins (PAPs), also known as the membrane fusion proteins (MFPs). In this review we summarize the recent advances in understanding of structural biology, function, and regulation of these systems, highlighting the previously undescribed role of PAPs in providing a common architectural scaffold across diverse families of transporters. Despite being built from a limited number of basic structural domains, these complexes present a staggering variety of architectures. While key insights have been derived from the RND transporter systems, a closer inspection of the operation and structural organization of different tripartite systems reveals unexpected analogies between them, including those formed around MFS- and ATP-driven transporters, suggesting that they operate around basic common principles. Based on that we are proposing a new integrated model of PAP-mediated communication within the conformational cycling of tripartite systems, which could be expanded to other types of assemblies.
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Affiliation(s)
- Ilyas Alav
- Institute
of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Jessica Kobylka
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Miriam S. Kuth
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Klaas M. Pos
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Martin Picard
- Laboratoire
de Biologie Physico-Chimique des Protéines Membranaires, CNRS
UMR 7099, Université de Paris, 75005 Paris, France
- Fondation
Edmond de Rothschild pour le développement de la recherche
Scientifique, Institut de Biologie Physico-Chimique, 75005 Paris, France
| | - Jessica M. A. Blair
- Institute
of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Vassiliy N. Bavro
- School
of Life Sciences, University of Essex, Colchester, CO4 3SQ United Kingdom
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22
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Ekka MK, Meena LS. Essential biochemical, biophysical and computational inputs on efficient functioning of Mycobacterium tuberculosis H 37Rv FtsY. Int J Biol Macromol 2021; 171:59-73. [PMID: 33412199 DOI: 10.1016/j.ijbiomac.2020.12.182] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/23/2020] [Accepted: 12/23/2020] [Indexed: 11/19/2022]
Abstract
Mycobacterium tuberculosis (M. tuberculosis H37Rv) utilizes the signal recognition particle pathway (SRP pathway) system for secretion of various proteins from ribosomes to the extracellular surface which plays an important role in the machinery running inside the bacterium. This system comprises of three major components FtsY, FfH and 4.5S rRNA. This manuscript highlights essential factors responsible for the optimized enzymatic activity of FtsY. Kinetic parameters include Vmax and Km for the hydrolysis of GTP by ftsY which were 20.25±5.16 μM/min/mg and 39.95±7.7 μM respectively. kcat and catalytic efficiency of the reaction were 0.012±0.003 s-1 and 0.00047±0.0001 μM/s-1 respectively. These values were affected upon changing the standard conditions. Cations (Mg2+ and Mn2+) play important role in FtsY enzymatic activity as increasing Mg2+ decrease the activity. Mn2+on the other hand is required at higher concentration around 60 mM for carrying optimum GTPase activity. FtsY is hydrolyzing ATP and GDP as well and GDP acts as an inhibitor of the reaction. MD simulation shows effective binding and stabilization of the FtsY complexed structure with GTP, GDP and ATP. Mutational analysis was done at two important residues of GTP binding motif of FtsY, namely, GXXXXGK (K236) and DXXG (D367) and showed that these mutations significantly decrease FtsY GTPase activity. FtsY is comprised of α helices, but this structural pattern was shown to change with increasing concentrations of GTP and ATP which symbolize that these ligands cause significant conformational change by variating the secondary structure to transduce signals required by downstream effectors. This binding favors the functional stabilization of FtsY by destabilization of α-helix integrity. Revealing the hidden aspects of the functioning of FtsY might be an essential part for the understanding of the SRP pathway which is one of the important contributors of M. tuberculosis virulence.
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Affiliation(s)
- Mary Krishna Ekka
- CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-HRDC, Ghaziabad, Uttar Pradesh 201 002, India
| | - Laxman S Meena
- CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-HRDC, Ghaziabad, Uttar Pradesh 201 002, India.
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23
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Garde S, Chodisetti PK, Reddy M. Peptidoglycan: Structure, Synthesis, and Regulation. EcoSal Plus 2021; 9:eESP-0010-2020. [PMID: 33470191 PMCID: PMC11168573 DOI: 10.1128/ecosalplus.esp-0010-2020] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Indexed: 02/06/2023]
Abstract
Peptidoglycan is a defining feature of the bacterial cell wall. Initially identified as a target of the revolutionary beta-lactam antibiotics, peptidoglycan has become a subject of much interest for its biology, its potential for the discovery of novel antibiotic targets, and its role in infection. Peptidoglycan is a large polymer that forms a mesh-like scaffold around the bacterial cytoplasmic membrane. Peptidoglycan synthesis is vital at several stages of the bacterial cell cycle: for expansion of the scaffold during cell elongation and for formation of a septum during cell division. It is a complex multifactorial process that includes formation of monomeric precursors in the cytoplasm, their transport to the periplasm, and polymerization to form a functional peptidoglycan sacculus. These processes require spatio-temporal regulation for successful assembly of a robust sacculus to protect the cell from turgor and determine cell shape. A century of research has uncovered the fundamentals of peptidoglycan biology, and recent studies employing advanced technologies have shed new light on the molecular interactions that govern peptidoglycan synthesis. Here, we describe the peptidoglycan structure, synthesis, and regulation in rod-shaped bacteria, particularly Escherichia coli, with a few examples from Salmonella and other diverse organisms. We focus on the pathway of peptidoglycan sacculus elongation, with special emphasis on discoveries of the past decade that have shaped our understanding of peptidoglycan biology.
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Affiliation(s)
- Shambhavi Garde
- These authors contributed equally
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India 500007
| | - Pavan Kumar Chodisetti
- These authors contributed equally
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India 500007
| | - Manjula Reddy
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India 500007
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The ATP-Binding Cassette (ABC) Transport Systems in Mycobacterium tuberculosis: Structure, Function, and Possible Targets for Therapeutics. BIOLOGY 2020; 9:biology9120443. [PMID: 33291531 PMCID: PMC7761784 DOI: 10.3390/biology9120443] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 11/06/2020] [Accepted: 11/12/2020] [Indexed: 12/22/2022]
Abstract
Simple Summary Mycobacterium tuberculosis is a bacterium of great medical importance because it causes tuberculosis, a disease that affects millions of people worldwide. Two important features are related to this bacterium: its ability to infect and survive inside the host, minimizing the immune response, and the burden of clinical isolates that are highly resistant to antibiotics treatment. These two phenomena are directly affected by cell envelope proteins, such as proteins from the ATP-Binding Cassette (ABC transporters) superfamily. In this review, we have compiled information on all the M. tuberculosis ABC transporters described so far, both from a functional and structural point of view, and show their relevance for the bacillus and the potential targets for studies aiming to control the microorganism and structural features. Abstract Mycobacterium tuberculosis is the etiological agent of tuberculosis (TB), a disease that affects millions of people in the world and that is associated with several human diseases. The bacillus is highly adapted to infect and survive inside the host, mainly because of its cellular envelope plasticity, which can be modulated to adapt to an unfriendly host environment; to manipulate the host immune response; and to resist therapeutic treatment, increasing in this way the drug resistance of TB. The superfamily of ATP-Binding Cassette (ABC) transporters are integral membrane proteins that include both importers and exporters. Both types share a similar structural organization, yet only importers have a periplasmic substrate-binding domain, which is essential for substrate uptake and transport. ABC transporter-type importers play an important role in the bacillus physiology through the transport of several substrates that will interfere with nutrition, pathogenesis, and virulence. Equally relevant, exporters have been involved in cell detoxification, nutrient recycling, and antibiotics and drug efflux, largely affecting the survival and development of multiple drug-resistant strains. Here, we review known ABC transporters from M. tuberculosis, with particular focus on the diversity of their structural features and relevance in infection and drug resistance.
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Shaku M, Ealand C, Kana BD. Cell Surface Biosynthesis and Remodeling Pathways in Mycobacteria Reveal New Drug Targets. Front Cell Infect Microbiol 2020; 10:603382. [PMID: 33282752 PMCID: PMC7688586 DOI: 10.3389/fcimb.2020.603382] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 10/20/2020] [Indexed: 12/29/2022] Open
Abstract
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), remains the leading cause of death from an infectious bacterium and is responsible for 1.8 million deaths annually. The emergence of drug resistance, together with the need for a shorter more effective regimen, has prompted the drive to identify novel therapeutics with the bacterial cell surface emerging as a tractable area for drug development. Mtb assembles a unique, waxy, and complex cell envelope comprised of the mycolyl-arabinogalactan-peptidoglycan complex and an outer capsule like layer, which are collectively essential for growth and pathogenicity while serving as an inherent barrier against antibiotics. A detailed understanding of the biosynthetic pathways required to assemble the polymers that comprise the cell surface will enable the identification of novel drug targets as these structures provide a diversity of biochemical reactions that can be targeted. Herein, we provide an overview of recently described mycobacterial cell wall targeting compounds, novel drug combinations and their modes of action. We anticipate that this summary will enable prioritization of the best pathways to target and triage of the most promising molecules to progress for clinical assessment.
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Affiliation(s)
- Moagi Shaku
- National Health Laboratory Service, Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
| | - Christopher Ealand
- National Health Laboratory Service, Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
| | - Bavesh D Kana
- National Health Laboratory Service, Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
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26
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Küssau T, Van Wyk N, Johansen MD, Alsarraf HMAB, Neyret A, Hamela C, Sørensen KK, Thygesen MB, Beauvineau C, Kremer L, Blaise M. Functional Characterization of the N-Acetylmuramyl-l-Alanine Amidase, Ami1, from Mycobacterium abscessus. Cells 2020; 9:cells9112410. [PMID: 33158165 PMCID: PMC7694207 DOI: 10.3390/cells9112410] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 10/27/2020] [Accepted: 10/29/2020] [Indexed: 11/08/2022] Open
Abstract
Peptidoglycan (PG) is made of a polymer of disaccharides organized as a three-dimensional mesh-like network connected together by peptidic cross-links. PG is a dynamic structure that is essential for resistance to environmental stressors. Remodeling of PG occurs throughout the bacterial life cycle, particularly during bacterial division and separation into daughter cells. Numerous autolysins with various substrate specificities participate in PG remodeling. Expression of these enzymes must be tightly regulated, as an excess of hydrolytic activity can be detrimental for the bacteria. In non-tuberculous mycobacteria such as Mycobacterium abscessus, the function of PG-modifying enzymes has been poorly investigated. In this study, we characterized the function of the PG amidase, Ami1 from M. abscessus. An ami1 deletion mutant was generated and the phenotypes of the mutant were evaluated with respect to susceptibility to antibiotics and virulence in human macrophages and zebrafish. The capacity of purified Ami1 to hydrolyze muramyl-dipeptide was demonstrated in vitro. In addition, the screening of a 9200 compounds library led to the selection of three compounds inhibiting Ami1 in vitro. We also report the structural characterization of Ami1 which, combined with in silico docking studies, allows us to propose a mode of action for these inhibitors.
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Affiliation(s)
- Tanja Küssau
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France; (T.K.); (N.V.W.); (M.D.J.); (H.M.A.B.A.); (C.H.)
| | - Niël Van Wyk
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France; (T.K.); (N.V.W.); (M.D.J.); (H.M.A.B.A.); (C.H.)
| | - Matt D. Johansen
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France; (T.K.); (N.V.W.); (M.D.J.); (H.M.A.B.A.); (C.H.)
| | - Husam M. A. B. Alsarraf
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France; (T.K.); (N.V.W.); (M.D.J.); (H.M.A.B.A.); (C.H.)
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark
| | - Aymeric Neyret
- CEMIPAI CNRS UM UMS3725, CEDEX 5, 34293 Montpellier, France;
| | - Claire Hamela
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France; (T.K.); (N.V.W.); (M.D.J.); (H.M.A.B.A.); (C.H.)
| | - Kasper K. Sørensen
- Department of Chemistry, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark; (K.K.S.); (M.B.T.)
| | - Mikkel B. Thygesen
- Department of Chemistry, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark; (K.K.S.); (M.B.T.)
| | - Claire Beauvineau
- Chemical Library Institut Curie/CNRS, CNRS UMR9187, INSERM U1196 and CNRS UMR3666, INSERM U1193, Université Paris-Saclay, F-91405 Orsay, France;
| | - Laurent Kremer
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France; (T.K.); (N.V.W.); (M.D.J.); (H.M.A.B.A.); (C.H.)
- INSERM, IRIM, 34293 Montpellier, France
- Correspondence: (L.K.); (M.B.); Tel.: +33-(0)-434-359-447 (L.K. & M.B.)
| | - Mickaël Blaise
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France; (T.K.); (N.V.W.); (M.D.J.); (H.M.A.B.A.); (C.H.)
- Correspondence: (L.K.); (M.B.); Tel.: +33-(0)-434-359-447 (L.K. & M.B.)
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Insights into bacterial cell division from a structure of EnvC bound to the FtsX periplasmic domain. Proc Natl Acad Sci U S A 2020; 117:28355-28365. [PMID: 33097670 PMCID: PMC7668044 DOI: 10.1073/pnas.2017134117] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The peptidoglycan layer is a core component of the bacterial cell envelope that provides a barrier to the environment and protection from osmotic shock. During division, bacteria must break and rebuild the peptidoglycan layer to enable separation of daughter cells. In E. coli, two of the three amidases responsible (AmiA and AmiB) are regulated by a single periplasmic activator (EnvC) that is, itself, controlled by an atypical ABC transporter (FtsEX) tethered to the cytoplasmic septal Z-ring. Here we define the structural basis for the interaction of FtsEX with EnvC and suggest a molecular mechanism for amidase activation where EnvC autoinhibition is relieved by ATP-driven conformational changes transmitted through the FtsEX-EnvC complex. FtsEX is a bacterial ABC transporter that regulates the activity of periplasmic peptidoglycan amidases via its interaction with the murein hydrolase activator, EnvC. In Escherichia coli, FtsEX is required to separate daughter cells after cell division and for viability in low-osmolarity media. Both the ATPase activity of FtsEX and its periplasmic interaction with EnvC are required for amidase activation, but the process itself is poorly understood. Here we present the 2.1 Å structure of the FtsX periplasmic domain in complex with its periplasmic partner, EnvC. The EnvC-FtsX periplasmic domain complex has a 1-to-2 stoichiometry with two distinct FtsX-binding sites located within an antiparallel coiled coil domain of EnvC. Residues involved in amidase activation map to a previously identified groove in the EnvC LytM domain that is here found to be occluded by a “restraining arm” suggesting a self-inhibition mechanism. Mutational analysis, combined with bacterial two-hybrid screens and in vivo functional assays, verifies the FtsEX residues required for EnvC binding and experimentally test a proposed mechanism for amidase activation. We also define a predicted link between FtsEX and integrity of the outer membrane. Both the ATPase activity of FtsEX and its periplasmic interaction with EnvC are required for resistance to membrane-attacking antibiotics and detergents to which E. coli would usually be considered intrinsically resistant. These structural and functional data provide compelling mechanistic insight into FtsEX-mediated regulation of EnvC and its downstream control of periplasmic peptidoglycan amidases.
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28
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The Cell Envelope Stress Response of Bacillus subtilis towards Laspartomycin C. Antibiotics (Basel) 2020; 9:antibiotics9110729. [PMID: 33114184 PMCID: PMC7690785 DOI: 10.3390/antibiotics9110729] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/19/2020] [Accepted: 10/21/2020] [Indexed: 11/17/2022] Open
Abstract
Cell wall antibiotics are important tools in our fight against Gram-positive pathogens, but many strains become increasingly resistant against existing drugs. Laspartomycin C is a novel antibiotic that targets undecaprenyl phosphate (UP), a key intermediate in the lipid II cycle of cell wall biosynthesis. While laspartomycin C has been thoroughly examined biochemically, detailed knowledge about potential resistance mechanisms in bacteria is lacking. Here, we use reporter strains to monitor the activity of central resistance modules in the Bacillus subtilis cell envelope stress response network during laspartomycin C attack and determine the impact on the resistance of these modules using knock-out strains. In contrast to the closely related UP-binding antibiotic friulimicin B, which only activates ECF σ factor-controlled stress response modules, we find that laspartomycin C additionally triggers activation of stress response systems reacting to membrane perturbation and blockage of other lipid II cycle intermediates. Interestingly, none of the studied resistance genes conferred any kind of protection against laspartomycin C. While this appears promising for therapeutic use of laspartomycin C, it raises concerns that existing cell envelope stress response networks may already be poised for spontaneous development of resistance during prolonged or repeated exposure to this new antibiotic.
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29
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Patil S, Palande A, Lodhiya T, Pandit A, Mukherjee R. Redefining genetic essentiality in Mycobacterium tuberculosis. Gene 2020; 765:145091. [PMID: 32898604 DOI: 10.1016/j.gene.2020.145091] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 08/18/2020] [Accepted: 08/21/2020] [Indexed: 11/15/2022]
Abstract
Sequencing transposon mutant libraries have been pivotal in annotating essential and non-essential genes in bacteria. This is particularly very helpful in the case of Mycobacterium tuberculosis with a large part of its genome without known function. It is not known whether there are any variations in the essentiality states as a function of optimal growth in the absence of any selection pressure. We here grow a high-density mutant library of M. tuberculosis through serial cultures and monitor the temporal fluctuations in insertion frequencies across all TA dinucleotides in the genome. Genes that cause morphological and physiological heterogeneity or enable metabolic bypass were found to gradually lose insertions, while genes comprising the toxin-antitoxin systems were found to get enriched with insertions during growth in nutrient replete conditions. High levels of fluctuations were observed in genes involved in cell wall and cell processes, intermediary metabolism, and genes involved in virulence, suggesting new modes of adaptation undertaken by the mutants. We also report the essentiality status of several newly annotated genetic features.
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Affiliation(s)
- Saniya Patil
- Department of Biology, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati 517507, India
| | - Aseem Palande
- Department of Biology, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati 517507, India
| | - Tejan Lodhiya
- Department of Biology, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati 517507, India
| | - Awadhesh Pandit
- National Center for Biological Sciences, Bengaluru 560065, India
| | - Raju Mukherjee
- Department of Biology, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati 517507, India.
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30
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Structural Characterization of the Essential Cell Division Protein FtsE and Its Interaction with FtsX in Streptococcus pneumoniae. mBio 2020; 11:mBio.01488-20. [PMID: 32873757 PMCID: PMC7468199 DOI: 10.1128/mbio.01488-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Bacterial cell division is a central process that requires exquisite orchestration of both the cell wall biosynthetic and lytic machineries. The essential membrane complex FtsEX, widely conserved across bacteria, plays a central role by recruiting proteins to the divisome apparatus and by regulating periplasmic muralytic activity from the cytosol. FtsEX is a member of the type VII family of the ABC-superfamily, but instead of being a transporter, it couples the ATP hydrolysis catalyzed by FtsE to mechanically transduce a conformational signal that provokes the activation of peptidoglycan (PG) hydrolases. So far, no structural information is available for FtsE. Here, we provide the structural characterization of FtsE, confirming its ATPase nature and revealing regions with high structural plasticity which are key for FtsE binding to FtsX. The complementary binding region in FtsX has also been identified and validated in vivo. Our results provide evidence on how the difference between the ATP/ADP-bound states in FtsE would dramatically alter the interaction of FtsEX with the PG hydrolase PcsB in pneumococcal division. FtsEX is a membrane complex widely conserved across diverse bacterial genera and involved in critical processes such as recruitment of division proteins and in spatial and temporal regulation of muralytic activity during cell division or sporulation. FtsEX is a member of the ABC transporter superfamily. The component FtsX is an integral membrane protein, whereas FtsE is an ATPase and is required for the transmission of a conformational signal from the cytosol through the membrane to regulate the activity of cell wall hydrolases in the periplasm. Both proteins are essential in the major human respiratory pathogenic bacterium Streptococcus pneumoniae, and FtsX interacts with the modular peptidoglycan hydrolase PcsB at the septum. Here, we report high-resolution structures of pneumococcal FtsE bound to different nucleotides. Structural analysis revealed that FtsE contains all the conserved structural motifs associated with ATPase activity and afforded interpretation of the in vivo dimeric arrangement in both the ADP and ATP states. Interestingly, three specific FtsE regions with high structural plasticity were identified that shape the cavity in which the cytosolic region of FtsX would be inserted. The residues corresponding to the FtsX coupling helix, responsible for contacting FtsE, were identified and validated by in vivo mutagenesis studies showing that this interaction is essential for cell growth and proper morphology.
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31
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Roles of ATP Hydrolysis by FtsEX and Interaction with FtsA in Regulation of Septal Peptidoglycan Synthesis and Hydrolysis. mBio 2020; 11:mBio.01247-20. [PMID: 32636250 PMCID: PMC7343993 DOI: 10.1128/mbio.01247-20] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
In Escherichia coli, FtsEX coordinates peptidoglycan (PG) synthesis and hydrolysis at the septum. It acts on FtsA in the cytoplasm to promote recruitment of septal PG synthetases and recruits EnvC, an activator of septal PG hydrolases, in the periplasm. Following recruitment, ATP hydrolysis by FtsEX is thought to regulate both PG synthesis and hydrolysis, but how it does this is not well understood. Here, we show that an ATPase mutant of FtsEX blocks septal PG synthesis similarly to cephalexin, suggesting that ATP hydrolysis by FtsEX is required throughout septation. Using mutants that uncouple the roles of FtsEX in septal PG synthesis and hydrolysis, we find that recruitment of EnvC to the septum by FtsEX, but not ATP hydrolysis, is required to promote cell separation when the NlpD-mediated cell separation system is present. However, ATP hydrolysis by FtsEX becomes necessary for efficient cell separation when the NlpD system is inactivated, suggesting that the ATPase activity of FtsEX is required for optimal activity of EnvC. Importantly, under conditions that suppress the role of FtsEX in cell division, disruption of the FtsEX-FtsA interaction delays cell separation, highlighting the importance of this interaction in coupling the cell separation system with the septal PG synthetic complex.IMPORTANCE Cytokinesis in Gram-negative bacteria requires coordinated invagination of the three layers of the cell envelope; otherwise, cells become sensitive to hydrophobic antibiotics and can even undergo cell lysis. In E. coli, the ABC transporter FtsEX couples the synthesis and hydrolysis of the stress-bearing peptidoglycan layer at the septum by interacting with FtsA and EnvC, respectively. ATP hydrolysis by FtsEX is critical for its function, but the reason why is not clear. Here, we find that in the absence of ATP hydrolysis, FtsEX blocks septal PG synthesis similarly to cephalexin. However, an FtsEX ATPase mutant, under conditions where it cannot block division, rescues ftsEX phenotypes as long as a partially redundant cell separation system is present. Furthermore, we find that the FtsEX-FtsA interaction is important for efficient cell separation.
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32
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Adu KT, Wilson R, Baker AL, Bowman J, Britz ML. Prolonged Heat Stress of Lactobacillus paracasei GCRL163 Improves Binding to Human Colorectal Adenocarcinoma HT-29 Cells and Modulates the Relative Abundance of Secreted and Cell Surface-Located Proteins. J Proteome Res 2020; 19:1824-1846. [PMID: 32108472 DOI: 10.1021/acs.jproteome.0c00107] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lactobacillus casei group bacteria improve cheese ripening and may interact with host intestinal cells as probiotics, where surface proteins play a key role. Three complementary methods [trypsin shaving (TS), LiCl-sucrose (LS) extraction, and extracellular culture fluid precipitation] were used to analyze cell surface proteins of Lactobacillus paracasei GCRL163 by label-free quantitative proteomics after culture to the mid-exponential phase in bioreactors at pH 6.5 and temperatures of 30-45 °C. A total of 416 proteins, including 300 with transmembrane, cell wall anchoring, and secretory motifs and 116 cytoplasmic proteins, were quantified as surface proteins. Although LS caused significantly greater cell lysis as growth temperature increased, higher numbers of extracytoplasmic proteins were exclusively obtained by LS treatment. Together with the increased positive surface charge of cells cultured at supra-optimal temperatures, proteins including cell wall hydrolases Msp1/p75 and Msp2/p40, α-fucosidase AlfB, SecA, and a PspC-domain putative adhesin were upregulated in surface or secreted protein fractions, suggesting that cell adhesion may be altered. Prolonged heat stress (PHS) increased binding of L. paracasei GCRL163 to human colorectal adenocarcinoma HT-29 cells, relative to acid-stressed cells. This study demonstrates that PHS influences cell adhesion and relative abundance of proteins located on the surface, which may impact probiotic functionality, and the detected novel surface proteins likely linked to the cell cycle and envelope stress.
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Affiliation(s)
- Kayode T Adu
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Richard Wilson
- Central Science Laboratory, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Anthony L Baker
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - John Bowman
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Margaret L Britz
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania 7001, Australia
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Do T, Page JE, Walker S. Uncovering the activities, biological roles, and regulation of bacterial cell wall hydrolases and tailoring enzymes. J Biol Chem 2020; 295:3347-3361. [PMID: 31974163 DOI: 10.1074/jbc.rev119.010155] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Bacteria account for 1000-fold more biomass than humans. They vary widely in shape and size. The morphological diversity of bacteria is due largely to the different peptidoglycan-based cell wall structures that encase bacterial cells. Although the basic structure of peptidoglycan is highly conserved, consisting of long glycan strands that are cross-linked by short peptide chains, the mature cell wall is chemically diverse. Peptidoglycan hydrolases and cell wall-tailoring enzymes that regulate glycan strand length, the degree of cross-linking, and the addition of other modifications to peptidoglycan are central in determining the final architecture of the bacterial cell wall. Historically, it has been difficult to biochemically characterize these enzymes that act on peptidoglycan because suitable peptidoglycan substrates were inaccessible. In this review, we discuss fundamental aspects of bacterial cell wall synthesis, describe the regulation and diverse biochemical and functional activities of peptidoglycan hydrolases, and highlight recently developed methods to make and label defined peptidoglycan substrates. We also review how access to these substrates has now enabled biochemical studies that deepen our understanding of how bacterial cell wall enzymes cooperate to build a mature cell wall. Such improved understanding is critical to the development of new antibiotics that disrupt cell wall biogenesis, a process essential to the survival of bacteria.
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Affiliation(s)
- Truc Do
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Julia E Page
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Suzanne Walker
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115.
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34
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Pichoff S, Du S, Lutkenhaus J. Roles of FtsEX in cell division. Res Microbiol 2019; 170:374-380. [PMID: 31376483 PMCID: PMC6899183 DOI: 10.1016/j.resmic.2019.07.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 07/09/2019] [Accepted: 07/16/2019] [Indexed: 02/04/2023]
Abstract
FtsEX is a member of a small subclass of ABC transporters that uses mechano-transmission to perform work in the periplasm. FtsEX controls periplasmic peptidoglycan (PG) hydrolase activities in many Gram negative and positive organisms to ensure the safe separation of daughter cells during division. In these organisms FtsEX localizes to the Z ring and uses its ATPase activity to regulate its periplasmic effectors. In Escherichia coli, FtsEX also participates in building the divisome and coordinates PG synthesis with PG hydrolysis. This review discusses studies that are beginning to elucidate the mechanisms of FtsEX's various roles in cell division.
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Affiliation(s)
- Sebastien Pichoff
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Shishen Du
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Joe Lutkenhaus
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, 66160, USA.
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35
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Mir MA, Srinivasan R, Ajitkumar P. MtFtsX a predicted membrane domain of ABC transporter complex MtFtsEX of Mycobacterium tuberculosis interacts with the cell division protein MtFtsZ. Int J Mycobacteriol 2019; 8:281-286. [PMID: 31512605 DOI: 10.4103/ijmy.ijmy_98_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Background Bacterial cytokinesis is orchestrated by a complex of dozen of proteins called 'divisome' at the mid-cell site. FtsZ, the eukaryotic tubulin homolog, localizes to the mid-cell site where it polymerizes and forms a cytokinetic Z-ring. The Z-ring acts as a docking platform for other proteins to localize. In model organisms, Escherichia coli and Bacillus subtilis, FtsZ is known to interact with several proteins. The role of few of these interactions is known, while of others is yet to be studied. In Mycobacterium tuberculosis, the cell division and its regulation are poorly studied. Although, most of the divisome proteins are conserved in M. tuberculosis, surprisingly the homologues of the protein factors required for membrane association of Z-ring and its stabilization are absent. In E. coli FtsE and FtsX, the constituent ATPase and membrane domains of the ABC transporter complex, localize to the Z-ring immediately after Z-ring stabilizing proteins, ZipA and FtsA. Therefore, investigation of the interaction between MtFtsX and MtFtsZ is demanding. Methods Bacterial two-hybrid system was used to identify the interaction between MtFtsE and MtFtsZ. This interaction was further confirmed by biochemical methods of Ni2+-NTA agarose pull-down and coimmunoprecipitation. Results and Conclusion Here, we demonstrated that MtFtsX interacts with MtFtsZ in vivo and ex-vivo. Further, we showed that self-interacting MtFtsX interacts with MtFtsE. However, we did not find any interaction between MtFtsE and MtFtsZ. These results suggest that the membrane domain MtFtsX of the ABC transporter complex 'MtFtsEX' might be the membrane-tethering and stabilizing factor for Z-ring in M. tuberculosis.
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Affiliation(s)
- Mushtaq Ahmad Mir
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Asir, Saudi Arabia
| | - Ramanujam Srinivasan
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, Odisha, India
| | - Parthasarathi Ajitkumar
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, Karnataka, India
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Brunet YR, Wang X, Rudner DZ. SweC and SweD are essential co-factors of the FtsEX-CwlO cell wall hydrolase complex in Bacillus subtilis. PLoS Genet 2019; 15:e1008296. [PMID: 31437162 PMCID: PMC6705773 DOI: 10.1371/journal.pgen.1008296] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 07/08/2019] [Indexed: 01/10/2023] Open
Abstract
The peptidoglycan (PG) sacculus is composed of long glycan strands cross-linked together by short peptides forming a covalently closed meshwork that protects the bacterial cell from osmotic lysis and specifies its shape. PG hydrolases play essential roles in remodeling this three-dimensional network during growth and division but how these autolytic enzymes are regulated remains poorly understood. The FtsEX ABC transporter-like complex has emerged as a broadly conserved regulatory module in controlling cell wall hydrolases in diverse bacterial species. In most characterized examples, this complex regulates distinct PG hydrolases involved in cell division and is intimately associated with the cytokinetic machinery called the divisome. However, in the gram-positive bacterium Bacillus subtilis the FtsEX complex is required for cell wall elongation where it regulates the PG hydrolase CwlO that acts along the lateral cell wall. To investigate whether additional factors are required for FtsEX function outside the divisome, we performed a synthetic lethal screen taking advantage of the conditional essentiality of CwlO. This screen identified two uncharacterized factors (SweD and SweC) that are required for CwlO activity. We demonstrate that these proteins reside in a membrane complex with FtsX and that amino acid substitutions in residues adjacent to the ATPase domain of FtsE partially bypass the requirement for them. Collectively our data indicate that SweD and SweC function as essential co-factors of FtsEX in controlling CwlO during cell wall elongation. We propose that factors analogous to SweDC function to support FtsEX activity outside the divisome in other bacteria.
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Affiliation(s)
- Yannick R. Brunet
- Department of Microbiology, Harvard Medical School, Boston, MA, United States of America
| | - Xindan Wang
- Department of Microbiology, Harvard Medical School, Boston, MA, United States of America
| | - David Z. Rudner
- Department of Microbiology, Harvard Medical School, Boston, MA, United States of America
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Lim HC, Sher JW, Rodriguez-Rivera FP, Fumeaux C, Bertozzi CR, Bernhardt TG. Identification of new components of the RipC-FtsEX cell separation pathway of Corynebacterineae. PLoS Genet 2019; 15:e1008284. [PMID: 31437147 PMCID: PMC6705760 DOI: 10.1371/journal.pgen.1008284] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 07/03/2019] [Indexed: 12/23/2022] Open
Abstract
Several important human pathogens are represented in the Corynebacterineae suborder, including Mycobacterium tuberculosis and Corynebacterium diphtheriae. These bacteria are surrounded by a multilayered cell envelope composed of a cytoplasmic membrane, a peptidoglycan (PG) cell wall, a second polysaccharide layer called the arabinogalactan (AG), and finally an outer membrane-like layer made of mycolic acids. Several anti-tuberculosis drugs target the biogenesis of this complex envelope, but their efficacy is declining due to resistance. New therapies are therefore needed to treat diseases caused by these organisms, and a better understanding of the mechanisms of envelope assembly should aid in their discovery. To this end, we generated the first high-density library of transposon insertion mutants in the model organism C. glutamicum. Transposon-sequencing was then used to define its essential gene set and identify loci that, when inactivated, confer hypersensitivity to ethambutol (EMB), a drug that targets AG biogenesis. Among the EMBs loci were genes encoding RipC and the FtsEX complex, a PG cleaving enzyme required for proper cell division and its predicted regulator, respectively. Inactivation of the conserved steAB genes (cgp_1603-1604) was also found to confer EMB hypersensitivity and cell division defects. A combination of quantitative microscopy, mutational analysis, and interaction studies indicate that SteA and SteB form a complex that localizes to the cytokinetic ring to promote cell separation by RipC-FtsEX and may coordinate its PG remodeling activity with the biogenesis of other envelope layers during cell division.
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Affiliation(s)
- Hoong Chuin Lim
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Joel W. Sher
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | | | - Coralie Fumeaux
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Carolyn R. Bertozzi
- Department of Chemistry, Stanford University, Stanford, California, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - Thomas G. Bernhardt
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
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Du S, Henke W, Pichoff S, Lutkenhaus J. How FtsEX localizes to the Z ring and interacts with FtsA to regulate cell division. Mol Microbiol 2019; 112:881-895. [PMID: 31175681 DOI: 10.1111/mmi.14324] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/05/2019] [Indexed: 12/14/2022]
Abstract
In Escherichia coli, FtsEX, a member of the ABC transporter superfamily, is involved in regulating the assembly and activation of the divisome to couple cell wall synthesis to cell wall hydrolysis at the septum. Genetic studies indicate FtsEX acts on FtsA to begin the recruitment of the downstream division proteins but blocks septal PG synthesis until a signal is received that divisome assembly is complete. However, the details of how FtsEX localizes to the Z ring and how it interacts with FtsA are not clear. Our results show that recruitment of FtsE and FtsX is codependent and suggest that the FtsEX complex is recruited through FtsE interacting with the conserved tail of FtsZ (CCTP), thus adding FtsEX to a growing list of proteins that interacts with the CCTP of FtsZ. Furthermore, we find that the N-terminus of FtsX is not required for FtsEX localization to the Z ring but is required for its functions in cell division indicating that it interacts with FtsA. Taken together, these results suggest that FtsEX first interacts with FtsZ to localize to the Z ring and then interacts with FtsA to promote divisome assembly and regulate septal PG synthesis.
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Affiliation(s)
- Shishen Du
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Wyatt Henke
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Sebastien Pichoff
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Joe Lutkenhaus
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, 66160, USA
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Squeglia F, Moreira M, Ruggiero A, Berisio R. The Cell Wall Hydrolytic NlpC/P60 Endopeptidases in Mycobacterial Cytokinesis: A Structural Perspective. Cells 2019; 8:cells8060609. [PMID: 31216697 PMCID: PMC6628586 DOI: 10.3390/cells8060609] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 06/12/2019] [Accepted: 06/14/2019] [Indexed: 12/11/2022] Open
Abstract
In preparation for division, bacteria replicate their DNA and segregate the newly formed chromosomes. A division septum then assembles between the chromosomes, and the mother cell splits into two identical daughters due to septum degradation. A major constituent of bacterial septa and of the whole cell wall is peptidoglycan (PGN), an essential cell wall polymer, formed by glycan chains of β−(1-4)-linked-N-acetylglucosamine (GlcNAc) and N-acetylmuramic acid (MurNAc), cross-linked by short peptide stems. Depending on the amino acid located at the third position of the peptide stem, PGN is classified as either Lys-type or meso-diaminopimelic acid (DAP)-type. Hydrolytic enzymes play a crucial role in the degradation of bacterial septa to split the cell wall material shared by adjacent daughter cells to promote their separation. In mycobacteria, a key PGN hydrolase, belonging to the NlpC/P60 endopeptidase family and denoted as RipA, is responsible for the degradation of septa, as the deletion of the gene encoding for this enzyme generates abnormal bacteria with multiple septa. This review provides an update of structural and functional data highlighting the central role of RipA in mycobacterial cytokinesis and the fine regulation of its catalytic activity, which involves multiple molecular partners.
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Affiliation(s)
- Flavia Squeglia
- Institute of Biostructures and Bioimaging (IBB), CNR, 80134 Naples, Italy.
| | - Miguel Moreira
- Institute of Biostructures and Bioimaging (IBB), CNR, 80134 Naples, Italy.
| | - Alessia Ruggiero
- Institute of Biostructures and Bioimaging (IBB), CNR, 80134 Naples, Italy.
| | - Rita Berisio
- Institute of Biostructures and Bioimaging (IBB), CNR, 80134 Naples, Italy.
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Abstract
How do mycobacteria divide? Cell division has been studied extensively in the model rod-shaped bacteria Escherichia coli and Bacillus subtilis, but much less is understood about cell division in mycobacteria, a genus that includes the major human pathogens M. tuberculosis and M. leprae. In general, bacterial cell division requires the concerted effort of many proteins in both space and time to elongate the cell, replicate and segregate the chromosome, and construct and destruct the septum - processes which result in the creation of two new daughter cells. Here, we describe these distinct stages of cell division in B. subtilis and follow with the current knowledge in mycobacteria. As will become apparent, there are many differences between mycobacteria and B. subtilis in terms of both the broad outline of cell division and the molecular details. So, while the fundamental challenge of spatially and temporally organizing cell division is shared between these rod-shaped bacteria, they have solved these challenges in often vastly different ways.
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Structure of the Large Extracellular Loop of FtsX and Its Interaction with the Essential Peptidoglycan Hydrolase PcsB in Streptococcus pneumoniae. mBio 2019; 10:mBio.02622-18. [PMID: 30696736 PMCID: PMC6355983 DOI: 10.1128/mbio.02622-18] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Streptococcus pneumoniae is a leading killer of infants and immunocompromised adults and has become increasingly resistant to major antibiotics. Therefore, the development of new antibiotic strategies is desperately needed. Targeting bacterial cell division is one such strategy, specifically by targeting proteins that are essential for the synthesis and breakdown of peptidoglycan. One complex important to this process is FtsEX. FtsEX comprises a cell division-regulating integral membrane protein (FtsX) and a cytoplasmic ATPase (FtsE) that resembles an ATP-binding cassette (ABC) transporter. Here, we present nuclear magnetic resonance (NMR) solution structural and crystallographic models of the large extracellular domain of FtsX, denoted extracellular loop 1 (ECL1). The structure of ECL1 reveals an upper extended β-hairpin and a lower α-helical lobe, each extending from a mixed α-β core. The helical lobe mediates a physical interaction with the peptidoglycan hydrolase PcsB via the coiled-coil domain of PcsB (PscBCC). Characterization of S. pneumoniae strain D39-derived strains harboring mutations in the α-helical lobe shows that this subdomain is essential for cell viability and required for proper cell division of S. pneumoniae IMPORTANCE FtsX is a ubiquitous bacterial integral membrane protein involved in cell division that regulates the activity of peptidoglycan (PG) hydrolases. FtsX is representative of a large group of ABC3 superfamily proteins that function as "mechanotransmitters," proteins that relay signals from the inside to the outside of the cell. Here, we present a structural characterization of the large extracellular loop, ECL1, of FtsX from the opportunistic human pathogen S. pneumoniae We show the molecular nature of the direct interaction between the peptidoglycan hydrolase PcsB and FtsX and demonstrate that this interaction is essential for cell viability. As such, FtsX represents an attractive, conserved target for the development of new classes of antibiotics.
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Insights into bacterial lipoprotein trafficking from a structure of LolA bound to the LolC periplasmic domain. Proc Natl Acad Sci U S A 2018; 115:E7389-E7397. [PMID: 30012603 DOI: 10.1073/pnas.1806822115] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In Gram-negative bacteria, outer-membrane lipoproteins are essential for maintaining cellular integrity, transporting nutrients, establishing infections, and promoting the formation of biofilms. The LolCDE ABC transporter, LolA chaperone, and LolB outer-membrane receptor form an essential system for transporting newly matured lipoproteins from the outer leaflet of the cytoplasmic membrane to the innermost leaflet of the outer membrane. Here, we present a crystal structure of LolA in complex with the periplasmic domain of LolC. The structure reveals how a solvent-exposed β-hairpin loop (termed the "Hook") and trio of surface residues (the "Pad") of LolC are essential for recruiting LolA from the periplasm and priming it to receive lipoproteins. Experiments with purified LolCDE complex demonstrate that association with LolA is independent of nucleotide binding and hydrolysis, and homology models based on the MacB ABC transporter predict that LolA recruitment takes place at a periplasmic site located at least 50 Å from the inner membrane. Implications for the mechanism of lipoprotein extraction and transfer are discussed. The LolA-LolC structure provides atomic details on a key protein interaction within the Lol pathway and constitutes a vital step toward the complete molecular understanding of this important system.
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Jain P, Malakar B, Khan MZ, Lochab S, Singh A, Nandicoori VK. Delineating FtsQ-mediated regulation of cell division in Mycobacterium tuberculosis. J Biol Chem 2018; 293:12331-12349. [PMID: 29903917 DOI: 10.1074/jbc.ra118.003628] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/31/2018] [Indexed: 11/06/2022] Open
Abstract
Identifying and characterizing the individual contributors to bacterial cellular elongation and division will improve our understanding of their impact on cell growth and division. Here, we delineated the role of ftsQ, a terminal gene of the highly conserved division cell wall (dcw) operon, in growth, survival, and cell length maintenance in the human pathogen Mycobacterium tuberculosis (Mtb). We found that FtsQ overexpression significantly increases the cell length and number of multiseptate cells. FtsQ depletion in Mtb resulted in cells that were shorter than WT cells during the initial growth stages (4 days after FtsQ depletion) but were longer than WT cells at later stages (10 days after FtsQ depletion) and compromised the survival in vitro and in differentiated THP1 macrophages. Overexpression of N- and C-terminal FtsQ regions altered the cell length, and the C-terminal domain alone complemented the FtsQ depletion phenotype. MS analyses suggested robust FtsQ phosphorylation on Thr-24, and although phosphoablative and -mimetic mutants rescued the FtsQ depletion-associated cell viability defects, they failed to complement the cell length defects. MS and coimmunoprecipitation experiments identified 63 FtsQ-interacting partners, and we show that the interaction of FtsQ with the recently identified cell division protein SepIVA is independent of FtsQ phosphorylation and suggests a role of FtsQ in modulating cell division. FtsQ exhibited predominantly septal localization in both the presence and absence of SepIVA. Our results suggest a role for FtsQ in modulating the length, division, and survival of Mtb cells both in vitro and in the host.
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Affiliation(s)
- Preeti Jain
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067 and
| | - Basanti Malakar
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067 and
| | - Mehak Zahoor Khan
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067 and
| | - Savita Lochab
- From the National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067 and
| | - Archana Singh
- Council of Scientific and Industrial Research-Institute of Genomics and Integrative Biology, New Delhi 110025, India
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Steiner EM, Lyngsø J, Guy JE, Bourenkov G, Lindqvist Y, Schneider TR, Pedersen JS, Schneider G, Schnell R. The structure of the N-terminal module of the cell wall hydrolase RipA and its role in regulating catalytic activity. Proteins 2018; 86:912-923. [DOI: 10.1002/prot.25523] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 04/17/2018] [Accepted: 04/25/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Eva Maria Steiner
- Department of Medical Biochemistry and Biophysics; Karolinska Institutet; Stockholm S-17 177 Sweden
| | - Jeppe Lyngsø
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO); Aarhus University, Gustav Wieds Vej 14; Aarhus DK-8000 Denmark
| | - Jodie E. Guy
- Department of Medical Biochemistry and Biophysics; Karolinska Institutet; Stockholm S-17 177 Sweden
| | - Gleb Bourenkov
- Hamburg Unit c/o DESY, European Molecular Biology Laboratory (EMBL), Notkestrasse 85; Hamburg 22603 Germany
| | - Ylva Lindqvist
- Department of Medical Biochemistry and Biophysics; Karolinska Institutet; Stockholm S-17 177 Sweden
| | - Thomas R. Schneider
- Hamburg Unit c/o DESY, European Molecular Biology Laboratory (EMBL), Notkestrasse 85; Hamburg 22603 Germany
| | - Jan Skov Pedersen
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO); Aarhus University, Gustav Wieds Vej 14; Aarhus DK-8000 Denmark
| | - Gunter Schneider
- Department of Medical Biochemistry and Biophysics; Karolinska Institutet; Stockholm S-17 177 Sweden
| | - Robert Schnell
- Department of Medical Biochemistry and Biophysics; Karolinska Institutet; Stockholm S-17 177 Sweden
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Greene NP, Kaplan E, Crow A, Koronakis V. Antibiotic Resistance Mediated by the MacB ABC Transporter Family: A Structural and Functional Perspective. Front Microbiol 2018; 9:950. [PMID: 29892271 PMCID: PMC5985334 DOI: 10.3389/fmicb.2018.00950] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 04/24/2018] [Indexed: 12/18/2022] Open
Abstract
The MacB ABC transporter forms a tripartite efflux pump with the MacA adaptor protein and TolC outer membrane exit duct to expel antibiotics and export virulence factors from Gram-negative bacteria. Here, we review recent structural and functional data on MacB and its homologs. MacB has a fold that is distinct from other structurally characterized ABC transporters and uses a unique molecular mechanism termed mechanotransmission. Unlike other bacterial ABC transporters, MacB does not transport substrates across the inner membrane in which it is based, but instead couples cytoplasmic ATP hydrolysis with transmembrane conformational changes that are used to perform work in the extra-cytoplasmic space. In the MacAB-TolC tripartite pump, mechanotransmission drives efflux of antibiotics and export of a protein toxin from the periplasmic space via the TolC exit duct. Homologous tripartite systems from pathogenic bacteria similarly export protein-like signaling molecules, virulence factors and siderophores. In addition, many MacB-like ABC transporters do not form tripartite pumps, but instead operate in diverse cellular processes including antibiotic sensing, cell division and lipoprotein trafficking.
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Affiliation(s)
- Nicholas P Greene
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Elise Kaplan
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Allister Crow
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Vassilis Koronakis
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
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The Opp (AmiACDEF) Oligopeptide Transporter Mediates Resistance of Serotype 2 Streptococcus pneumoniae D39 to Killing by Chemokine CXCL10 and Other Antimicrobial Peptides. J Bacteriol 2018; 200:JB.00745-17. [PMID: 29581408 DOI: 10.1128/jb.00745-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 03/22/2018] [Indexed: 12/12/2022] Open
Abstract
Antimicrobial peptides (AMPs), including chemokines, are produced during infections to kill pathogenic bacteria. To fill in gaps in knowledge about the sensitivities of Streptococcus pneumoniae and related Streptococcus species to chemokines and AMPs, we performed a systematic, quantitative study of inhibition by chemokine CXCL10 and the AMPs LL-37 and nisin. In a standard Tris-glucose buffer (TGS), all strains assayed lacked metabolic activity, as determined by resazurin (alamarBlue) reduction, and were extremely sensitive to CXCL10 and AMPs (50% inhibitory concentration [IC50], ∼0.04 μM). In TGS, changes in sensitivities caused by mutations were undetectable. In contrast, strains that retained reductive metabolic activity in a different assay buffer (NPB [10 mM sodium phosphate {pH 7.4}, 1% {vol/vol} brain heart infusion {BHI} broth]) were less sensitive to CXCL10 and AMPs than in TGS. In NPB, mutants known to respond to AMPs, such as Δdlt mutants lacking d-alanylation of teichoic acids, exhibited the expected increased sensitivity. S. pneumoniae serotype 2 strain D39 was much (∼10-fold) less sensitive to CXCL10 killing in NPB than serotype 4 strain TIGR4, and the sensitivity of TIGR4 was unaffected by the absence of capsule. Candidate screening of strain D39 revealed that mutants lacking Opp (ΔamiACDEF) oligopeptide permease were significantly more resistant to CXCL10 than the wild-type strain. This increased resistance could indicate that Opp is a target for CXCL10 binding or that it transports CXCL10 into cells. Finally, ΔftsX or ΔftsE mutants of Bacillus subtilis or amino acid changes that interfere with FtsX function in S. pneumoniae did not impart resistance to CXCL10, in contrast to previous results for Bacillus anthracis, indicating that FtsX is not a general target for CXCL10 binding.IMPORTANCES. pneumoniae (pneumococcus) is a human commensal bacterium and major opportunistic respiratory pathogen that causes serious invasive diseases, killing millions of people worldwide annually. Because of its increasing antibiotic resistance, S. pneumoniae is now listed as a "superbug" for which new antibiotics are urgently needed. This report fills in knowledge gaps and resolves inconsistencies in the scientific literature about the sensitivity of S. pneumoniae and related Streptococcus pathogens to chemokines and AMPs. It also reveals a new mechanism by which S. pneumoniae can acquire resistance to chemokine CXCL10. This mechanism involves the Opp (AmiACDEF) oligopeptide transporter, which plays additional pleiotropic roles in pneumococcal physiology, quorum sensing, and virulence. Taking the results together, this work provides new information about the way chemokines kill pneumococcal cells.
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Burian J, Thompson CJ. Regulatory genes coordinating antibiotic-induced changes in promoter activity and early transcriptional termination of the mycobacterial intrinsic resistance gene whiB7. Mol Microbiol 2017; 107:402-415. [DOI: 10.1111/mmi.13890] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 11/22/2017] [Accepted: 11/30/2017] [Indexed: 01/30/2023]
Affiliation(s)
- Ján Burian
- Department of Microbiology and Immunology and the Centre for Tuberculosis Research; University of British Columbia; Vancouver V6T 1Z3 Canada
| | - Charles J. Thompson
- Department of Microbiology and Immunology and the Centre for Tuberculosis Research; University of British Columbia; Vancouver V6T 1Z3 Canada
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Djorić D, Kristich CJ. Extracellular SalB Contributes to Intrinsic Cephalosporin Resistance and Cell Envelope Integrity in Enterococcus faecalis. J Bacteriol 2017; 199:e00392-17. [PMID: 28874409 PMCID: PMC5686589 DOI: 10.1128/jb.00392-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 08/30/2017] [Indexed: 11/20/2022] Open
Abstract
Enterococci are major causes of hospital-acquired infections. Intrinsic resistance to cephalosporins is a universal trait among clinically relevant enterococci. Cephalosporin resistance enables enterococci to proliferate to high densities in the intestines of patients undergoing cephalosporin treatment, a precursor to the emergence of infection. However, the genetic and biochemical mechanisms of intrinsic cephalosporin resistance in enterococci are not well understood. A two-component signal transduction system, CroR/S, is required for cephalosporin resistance in enterococci. Although the CroR/S regulon is not well defined, one gene reported to be CroR dependent in Enterococcus faecalis JH2-2 encodes an extracellular putative peptidoglycan hydrolase, SalB. To test the hypothesis that SalB is responsible for CroR-dependent cephalosporin resistance, we examined ΔsalB mutants in multiple genetic lineages of E. faecalis, revealing that SalB is required not only for intrinsic cephalosporin resistance but also for maintenance of cell envelope integrity in the absence of antibiotic stress. The N-terminal signal sequence is necessary for SalB secretion, and secretion is required for SalB to promote cephalosporin resistance. Functional dissection revealed that the C-terminal SCP domain of SalB is essential for biological activity and identified three residues within the SCP domain that are required for the stability and function of SalB. Additionally, we found that in contrast to what is seen in E. faecalis JH2-2, SalB is not regulated by the CroR/S two-component system in E. faecalis OG1, suggesting diversity in the CroR/S regulon among distinct lineages of E. faecalis IMPORTANCE Resistance to cephalosporins is universal among clinically relevant enterococci, enabling enterococcal proliferation to high densities in the intestines of patients undergoing cephalosporin treatment, a precursor to the emergence of infection. Disabling cephalosporin resistance could therefore reduce the incidence of enterococcal infections. However, the genetic and biochemical mechanisms of cephalosporin resistance are not well understood. The significance of this work is the identification of a novel extracellular factor (SalB) that promotes cephalosporin resistance in E. faecalis, which could potentially serve as a target for therapeutics that impair enterococcal cephalosporin resistance. Additionally, our work highlights the importance of the C-terminal SCP domain of SalB, including several conserved residues within the SCP domain, for the ability of SalB to promote cephalosporin resistance.
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Affiliation(s)
- Dušanka Djorić
- Department of Microbiology and Immunology, Center for Infectious Disease Research, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Christopher J Kristich
- Department of Microbiology and Immunology, Center for Infectious Disease Research, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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Structure and mechanotransmission mechanism of the MacB ABC transporter superfamily. Proc Natl Acad Sci U S A 2017; 114:12572-12577. [PMID: 29109272 DOI: 10.1073/pnas.1712153114] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
MacB is an ABC transporter that collaborates with the MacA adaptor protein and TolC exit duct to drive efflux of antibiotics and enterotoxin STII out of the bacterial cell. Here we present the structure of ATP-bound MacB and reveal precise molecular details of its mechanism. The MacB transmembrane domain lacks a central cavity through which substrates could be passed, but instead conveys conformational changes from one side of the membrane to the other, a process we term mechanotransmission. Comparison of ATP-bound and nucleotide-free states reveals how reversible dimerization of the nucleotide binding domains drives opening and closing of the MacB periplasmic domains via concerted movements of the second transmembrane segment and major coupling helix. We propose that the assembled tripartite pump acts as a molecular bellows to propel substrates through the TolC exit duct, driven by MacB mechanotransmission. Homologs of MacB that do not form tripartite pumps, but share structural features underpinning mechanotransmission, include the LolCDE lipoprotein trafficking complex and FtsEX cell division signaling protein. The MacB architecture serves as the blueprint for understanding the structure and mechanism of an entire ABC transporter superfamily and the many diverse functions it supports.
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Zielińska A, Billini M, Möll A, Kremer K, Briegel A, Izquierdo Martinez A, Jensen GJ, Thanbichler M. LytM factors affect the recruitment of autolysins to the cell division site in Caulobacter crescentus. Mol Microbiol 2017; 106:419-438. [PMID: 28833791 DOI: 10.1111/mmi.13775] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/18/2017] [Indexed: 12/24/2022]
Abstract
Most bacteria possess a peptidoglycan cell wall that determines their morphology and provides mechanical robustness during osmotic challenges. The biosynthesis of this structure is achieved by a large set of synthetic and lytic enzymes with varying substrate specificities. Although the biochemical functions of these proteins are conserved and well-investigated, the precise roles of individual factors and the regulatory mechanisms coordinating their activities in time and space remain incompletely understood. Here, we comprehensively analyze the autolytic machinery of the alphaproteobacterial model organism Caulobacter crescentus, with a specific focus on LytM-like endopeptidases, soluble lytic transglycosylases and amidases. Our data reveal a high degree of redundancy within each protein family but also specialized functions for individual family members under stress conditions. In addition, we identify two lytic transglycosylases and an amidase as new divisome components that are recruited to midcell at distinct stages of the cell cycle. The midcell localization of these proteins is affected by two LytM factors with degenerate catalytic domains, DipM and LdpF, which may serve as regulatory hubs coordinating the activities of multiple autolytic enzymes during cell constriction and fission respectively. These findings set the stage for in-depth studies of the molecular mechanisms that control peptidoglycan remodeling in C. crescentus.
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Affiliation(s)
- Aleksandra Zielińska
- Faculty of Biology, Philipps-Universität, Marburg 35043, Germany.,Max Planck Institute for Terrestrial Microbiology, Marburg 35043, Germany
| | - Maria Billini
- Faculty of Biology, Philipps-Universität, Marburg 35043, Germany.,Max Planck Institute for Terrestrial Microbiology, Marburg 35043, Germany
| | - Andrea Möll
- Faculty of Biology, Philipps-Universität, Marburg 35043, Germany.,Max Planck Institute for Terrestrial Microbiology, Marburg 35043, Germany
| | - Katharina Kremer
- Faculty of Biology, Philipps-Universität, Marburg 35043, Germany
| | - Ariane Briegel
- Divison of Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA
| | - Adrian Izquierdo Martinez
- Faculty of Biology, Philipps-Universität, Marburg 35043, Germany.,Max Planck Institute for Terrestrial Microbiology, Marburg 35043, Germany
| | - Grant J Jensen
- Divison of Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA
| | - Martin Thanbichler
- Faculty of Biology, Philipps-Universität, Marburg 35043, Germany.,Max Planck Institute for Terrestrial Microbiology, Marburg 35043, Germany.,LOEWE Center for Synthetic Microbiology, Marburg 35043, Germany
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