1
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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] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 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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2
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Ong JWJ, Tan KS, Lee JJX, Seet JE, Choi HW, Ler SG, Gunaratne J, Narasaraju T, Sham LT, Patzel V, Chow VT. Differential effects of microRNAs miR-21, miR-99 and miR-145 on lung regeneration and inflammation during recovery from influenza pneumonia. J Med Virol 2023; 95:e29286. [PMID: 38087452 DOI: 10.1002/jmv.29286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 10/10/2023] [Accepted: 11/18/2023] [Indexed: 12/18/2023]
Abstract
In a mouse model of influenza pneumonia, we previously documented that proliferating alveolar type II (AT2) cells are the major stem cells involved in early lung recovery. Profiling of microRNAs revealed significant dysregulation of specific ones, including miR-21 and miR-99a. Moreover, miR-145 is known to exhibit antagonism to miR-21. This follow-up study investigated the roles of microRNAs miR-21, miR-99a, and miR-145 in the murine pulmonary regenerative process and inflammation during influenza pneumonia. Inhibition of miR-21 resulted in severe morbidity, and in significantly decreased proliferating AT2 cells due to impaired transition from innate to adaptive immune responses. Knockdown of miR-99a culminated in moderate morbidity, with a significant increase in proliferating AT2 cells that may be linked to PTEN downregulation. In contrast, miR-145 antagonism did not impact morbidity nor the proliferating AT2 cell population, and was associated with downregulation of TNF-alpha, IL1-beta, YM1, and LY6G. Hence, a complex interplay exists between expression of specific miRNAs, lung regeneration, and inflammation during recovery from influenza pneumonia. Inhibition of miR-21 and miR-99a (but not miR-145) can lead to deleterious cellular and molecular effects on pulmonary repair and inflammatory processes during influenza pneumonia.
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Affiliation(s)
- Joe Wee Jian Ong
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Kai Sen Tan
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | | | - Ju Ee Seet
- Department of Pathology, National University of Singapore, Singapore
| | - Hyung Won Choi
- Department of Medicine, National University of Singapore, Singapore
| | | | | | - Teluguakula Narasaraju
- Adichunchanagiri Institute of Medical Sciences, Adichunchanagiri University, Karnataka, India
| | - Lok-To Sham
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Volker Patzel
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- Department of Medicine, University of Cambridge, Cambridge, UK
| | - Vincent T Chow
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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3
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Yu L, Xu X, Chua WZ, Feng H, Ser Z, Shao K, Shi J, Wang Y, Li Z, Sobota RM, Sham LT, Luo M. Structural basis of peptide secretion for Quorum sensing by ComA. Nat Commun 2023; 14:7178. [PMID: 37935699 PMCID: PMC10630487 DOI: 10.1038/s41467-023-42852-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 10/23/2023] [Indexed: 11/09/2023] Open
Abstract
Quorum sensing (QS) is a crucial regulatory mechanism controlling bacterial signalling and holds promise for novel therapies against antimicrobial resistance. In Gram-positive bacteria, such as Streptococcus pneumoniae, ComA is a conserved efflux pump responsible for the maturation and secretion of peptide signals, including the competence-stimulating peptide (CSP), yet its structure and function remain unclear. Here, we functionally characterize ComA as an ABC transporter with high ATP affinity and determined its cryo-EM structures in the presence or absence of CSP or nucleotides. Our findings reveal a network of strong electrostatic interactions unique to ComA at the intracellular gate, a putative binding pocket for two CSP molecules, and negatively charged residues facilitating CSP translocation. Mutations of these residues affect ComA's peptidase activity in-vitro and prevent CSP export in-vivo. We demonstrate that ATP-Mg2+ triggers the outward-facing conformation of ComA for CSP release, rather than ATP alone. Our study provides molecular insights into the QS signal peptide secretion, highlighting potential targets for QS-targeting drugs.
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Affiliation(s)
- Lin Yu
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, 225001, Jiangsu, China
| | - Xin Xu
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore
| | - Wan-Zhen Chua
- Infectious Diseases Translational Research Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117545, Singapore
| | - Hao Feng
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore
| | - Zheng Ser
- Functional Proteomics Laboratory, SingMass National Laboratory, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, 138673, Singapore
| | - Kai Shao
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore
| | - Jian Shi
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore
- Center for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore
| | - Yumei Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing, 100190, China
| | - Zongli Li
- Harvard Cryo-EM Center for Structural Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Radoslaw M Sobota
- Functional Proteomics Laboratory, SingMass National Laboratory, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, 138673, 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, 117545, Singapore.
| | - Min Luo
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore.
- Center for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore.
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4
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Su T, Chua WZ, Liu Y, Fan J, Tan SY, Yang DW, Sham LT. Rewiring the pneumococcal capsule pathway for investigating glycosyltransferase specificity and genetic glycoengineering. Sci Adv 2023; 9:eadi8157. [PMID: 37672581 PMCID: PMC10482335 DOI: 10.1126/sciadv.adi8157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 08/03/2023] [Indexed: 09/08/2023]
Abstract
Virtually all living cells are covered with glycans. Their structures are primarily controlled by the specificities of glycosyltransferases (GTs). GTs typically adopt one of the three folds, namely, GT-A, GT-B, and GT-C. However, what defines their specificities remain poorly understood. Here, we developed a genetic glycoengineering platform by reprogramming the capsular polysaccharide pathways in Streptococcus pneumoniae to interrogate GT specificity and manipulate glycan structures. Our findings suggest that the central cleft of GT-B enzymes is important for determining acceptor specificity. The constraint of the glycoengineering platform was partially alleviated when the specificity of the precursor transporter was reduced, indicating that the transporter contributes to the overall fidelity of glycan synthesis. We also modified the pneumococcal capsule to produce several medically important mammalian glycans, as well as demonstrated the importance of regiochemistry in a glycosidic linkage on binding lung epithelial cells. Our work provided mechanistic insights into GT specificity and an approach for investigating glycan functions.
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Affiliation(s)
- Tong Su
- Infectious Diseases Translational Research Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117545, Singapore
| | - Wan-Zhen Chua
- Infectious Diseases Translational Research Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117545, Singapore
| | - Yao Liu
- Infectious Diseases Translational Research Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117545, Singapore
| | - Jingsong Fan
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117545, Singapore
| | - Si-Yin Tan
- Infectious Diseases Translational Research Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117545, Singapore
| | - Dai-wen Yang
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117545, 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 117545, Singapore
- 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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5
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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6
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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: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 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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7
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Chun YY, Tan KS, Yu L, Pang M, Wong MHM, Nakamoto R, Chua WZ, Huee-Ping Wong A, Lew ZZR, Ong HH, Chow VT, Tran T, Yun Wang D, Sham LT. Influence of glycan structure on the colonization of Streptococcus pneumoniae on human respiratory epithelial cells. Proc Natl Acad Sci U S A 2023; 120:e2213584120. [PMID: 36943879 PMCID: PMC10068763 DOI: 10.1073/pnas.2213584120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 02/10/2023] [Indexed: 03/23/2023] Open
Abstract
Virtually all living cells are encased in glycans. They perform key cellular functions such as immunomodulation and cell-cell recognition. Yet, how their composition and configuration affect their functions remains enigmatic. Here, we constructed isogenic capsule-switch mutants harboring 84 types of capsular polysaccharides (CPSs) in Streptococcus pneumoniae. This collection enables us to systematically measure the affinity of structurally related CPSs to primary human nasal and bronchial epithelial cells. Contrary to the paradigm, the surface charge does not appreciably affect epithelial cell binding. Factors that affect adhesion to respiratory cells include the number of rhamnose residues and the presence of human-like glycomotifs in CPS. Besides, pneumococcal colonization stimulated the production of interleukin 6 (IL-6), granulocyte-macrophage colony-stimulating factor (GM-CSF), and monocyte chemoattractantprotein-1 (MCP-1) in nasal epithelial cells, which also appears to be dependent on the serotype. Together, our results reveal glycomotifs of surface polysaccharides that are likely to be important for colonization and survival in the human airway.
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Affiliation(s)
- Ye-Yu Chun
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
| | - Kai Sen Tan
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Otolaryngology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117597
| | - Lisa Yu
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- College of Art and Sciences, Cornell University, Ithaca, NY14853
| | - Michelle Pang
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
| | - Ming Hui Millie Wong
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
| | - Rei Nakamoto
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
| | - Wan-Zhen Chua
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
| | - Amanda Huee-Ping Wong
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117593
| | - Zhe Zhang Ryan Lew
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
| | - Hsiao Hui Ong
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
| | - Vincent T. Chow
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
| | - Thai Tran
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117593
| | - De Yun Wang
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
| | - Lok-To Sham
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore117545
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8
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Loke MF, Yadav I, Lim TK, van der Maarel JRC, Sham LT, Chow VT. SARS-CoV-2 Spike Protein and Mouse Coronavirus Inhibit Biofilm Formation by Streptococcus pneumoniae and Staphylococcus aureus. Int J Mol Sci 2022; 23:ijms23063291. [PMID: 35328711 PMCID: PMC8950232 DOI: 10.3390/ijms23063291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 03/15/2022] [Accepted: 03/16/2022] [Indexed: 12/04/2022] Open
Abstract
The presence of co-infections or superinfections with bacterial pathogens in COVID-19 patients is associated with poor outcomes, including increased morbidity and mortality. We hypothesized that SARS-CoV-2 and its components interact with the biofilms generated by commensal bacteria, which may contribute to co-infections. This study employed crystal violet staining and particle-tracking microrheology to characterize the formation of biofilms by Streptococcus pneumoniae and Staphylococcus aureus that commonly cause secondary bacterial pneumonia. Microrheology analyses suggested that these biofilms were inhomogeneous soft solids, consistent with their dynamic characteristics. Biofilm formation by both bacteria was significantly inhibited by co-incubation with recombinant SARS-CoV-2 spike S1 subunit and both S1 + S2 subunits, but not with S2 extracellular domain nor nucleocapsid protein. Addition of spike S1 and S2 antibodies to spike protein could partially restore bacterial biofilm production. Furthermore, biofilm formation in vitro was also compromised by live murine hepatitis virus, a related beta-coronavirus. Supporting data from LC-MS-based proteomics of spike-biofilm interactions revealed differential expression of proteins involved in quorum sensing and biofilm maturation, such as the AI-2E family transporter and LuxS, a key enzyme for AI-2 biosynthesis. Our findings suggest that these opportunistic pathogens may egress from biofilms to resume a more virulent planktonic lifestyle during coronavirus infections. The dispersion of pathogens from biofilms may culminate in potentially severe secondary infections with poor prognosis. Further detailed investigations are warranted to establish bacterial biofilms as risk factors for secondary pneumonia in COVID-19 patients.
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Affiliation(s)
- Mun Fai Loke
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117545, Singapore; (M.F.L.); (L.-T.S.)
| | - Indresh Yadav
- Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore; (I.Y.); (J.R.C.v.d.M.)
| | - Teck Kwang Lim
- Protein and Proteomics Centre, Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117558, Singapore;
| | - Johan R. C. van der Maarel
- Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore; (I.Y.); (J.R.C.v.d.M.)
| | - Lok-To Sham
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117545, Singapore; (M.F.L.); (L.-T.S.)
| | - Vincent T. Chow
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117545, Singapore; (M.F.L.); (L.-T.S.)
- Correspondence:
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9
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Eichner H, Karlsson J, Spelmink L, Pathak A, Sham LT, Henriques-Normark B, Loh E. RNA thermosensors facilitate Streptococcus pneumoniae and Haemophilus influenzae immune evasion. PLoS Pathog 2021; 17:e1009513. [PMID: 33914847 PMCID: PMC8084184 DOI: 10.1371/journal.ppat.1009513] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 03/29/2021] [Indexed: 11/18/2022] Open
Abstract
Bacterial meningitis is a major cause of death and disability in children worldwide. Two human restricted respiratory pathogens, Streptococcus pneumoniae and Haemophilus influenzae, are the major causative agents of bacterial meningitis, attributing to 200,000 deaths annually. These pathogens are often part of the nasopharyngeal microflora of healthy carriers. However, what factors elicit them to disseminate and cause invasive diseases, remain unknown. Elevated temperature and fever are hallmarks of inflammation triggered by infections and can act as warning signals to pathogens. Here, we investigate whether these respiratory pathogens can sense environmental temperature to evade host complement-mediated killing. We show that productions of two vital virulence factors and vaccine components, the polysaccharide capsules and factor H binding proteins, are temperature dependent, thus influencing serum/opsonophagocytic killing of the bacteria. We identify and characterise four novel RNA thermosensors in S. pneumoniae and H. influenzae, responsible for capsular biosynthesis and production of factor H binding proteins. Our data suggest that these bacteria might have independently co-evolved thermosensing abilities with different RNA sequences but distinct secondary structures to evade the immune system.
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Affiliation(s)
- Hannes Eichner
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - Jens Karlsson
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - Laura Spelmink
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - Anuj Pathak
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - Lok-To Sham
- Infectious Disease Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Birgitta Henriques-Normark
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
- Clinical Microbiology, Bioclinicum, Karolinska University Hospital, Solna, Sweden
- Lee Kong Chian School of Medicine and Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - Edmund Loh
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
- Clinical Microbiology, Bioclinicum, Karolinska University Hospital, Solna, Sweden
- Lee Kong Chian School of Medicine and Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
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10
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Su T, Nakamoto R, Chun YY, Chua WZ, Chen JH, Zik JJ, Sham LT. Decoding capsule synthesis in Streptococcus pneumoniae. FEMS Microbiol Rev 2020; 45:6041728. [PMID: 33338218 DOI: 10.1093/femsre/fuaa067] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 12/07/2020] [Indexed: 12/20/2022] Open
Abstract
Streptococcus pneumoniae synthesizes more than one hundred types of capsular polysaccharides (CPS). While the diversity of the enzymes and transporters involved is enormous, it is not limitless. In this review, we summarized the recent progress on elucidating the structure-function relationships of CPS, the mechanisms by which they are synthesized, how their synthesis is regulated, the host immune response against them, and the development of novel pneumococcal vaccines. Based on the genetic and structural information available, we generated provisional models of the CPS repeating units that remain unsolved. In addition, to facilitate cross-species comparisons and assignment of glycosyltransferases, we illustrated the biosynthetic pathways of the known CPS in a standardized format. Studying the intricate steps of pneumococcal CPS assembly promises to provide novel insights for drug and vaccine development as well as improve our understanding of related pathways in other species.
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Affiliation(s)
- Tong Su
- Infectious Diseases Translational Research Programme, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117545, Singapore
| | - Rei Nakamoto
- Infectious Diseases Translational Research Programme, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117545, Singapore
| | - Ye Yu Chun
- Infectious Diseases Translational Research Programme, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117545, Singapore
| | - Wan Zhen Chua
- Infectious Diseases Translational Research Programme, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117545, Singapore
| | - Jia Hui Chen
- Infectious Diseases Translational Research Programme, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117545, Singapore
| | - Justin J Zik
- Infectious Diseases Translational Research Programme, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117545, Singapore
| | - Lok-To Sham
- Infectious Diseases Translational Research Programme, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117545, Singapore
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11
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Tan YH, Chen Y, Chu WHW, Sham LT, Gan YH. Cell envelope defects of different capsule-null mutants in K1 hypervirulent Klebsiella pneumoniae can affect bacterial pathogenesis. Mol Microbiol 2020; 113:889-905. [PMID: 31912541 PMCID: PMC7317392 DOI: 10.1111/mmi.14447] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 01/03/2020] [Accepted: 01/05/2020] [Indexed: 01/08/2023]
Abstract
Hypervirulent Klebsiella pneumoniae (hvKP) causes Klebsiella‐induced liver abscess. Capsule is important for the pathogenesis of Klebsiella in systemic infection, but its role in gut colonisation is not well understood. By generating ΔwcaJ, Δwza and Δwzy capsule‐null mutants in a prototypical K1 hypervirulent isolate, we show that inactivation of wza (capsule exportase) and wzy (capsule polymerase) confer cell envelope defects in addition to capsule loss, making them susceptible to bile salts and detergent stress. Bile salt resistance is restored when the initial glycosyltransferase wcaJ was inactivated together with wzy, indicating that build‐up of capsule intermediates contribute to cell envelope defects. Mouse gut colonisation competition assays show that the capsule and its regulator RmpA were not required for hvKP to persist in the gut, although initial colonisation was decreased in the mutants. Both ΔrmpA and ΔwcaJ mutants gradually outcompeted the wild type in the gut, whereas Δwza and Δwzy mutants were less fit than wild type. Together, our results advise caution in using the right capsule‐null mutant for determination of capsule's role in bacterial pathogenesis. With the use of ΔwcaJ mutant, we found that although the capsule is important for bacterial survival outside the gut environment, it imposes a fitness cost in the gut.
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Affiliation(s)
- Yi Han Tan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Yahua Chen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Wilson H W Chu
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Lok-To Sham
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Yunn-Hwen Gan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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12
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Kocaoglu O, Calvo RA, Sham LT, Cozy LM, Lanning BR, Francis S, Winkler ME, Kearns DB, Carlson EE. Selective Penicillin-Binding Protein Imaging Probes Reveal Substructure in Bacterial Cell Division. ACS Chem Biol 2019; 14:1672. [PMID: 31265231 DOI: 10.1021/acschembio.9b00459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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13
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Baranowski C, Welsh MA, Sham LT, Eskandarian HA, Lim HC, Kieser KJ, Wagner JC, McKinney JD, Fantner GE, Ioerger TR, Walker S, Bernhardt TG, Rubin EJ, Rego EH. Maturing Mycobacterium smegmatis peptidoglycan requires non-canonical crosslinks to maintain shape. eLife 2018; 7:37516. [PMID: 30324906 PMCID: PMC6231781 DOI: 10.7554/elife.37516] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 10/11/2018] [Indexed: 01/06/2023] Open
Abstract
In most well-studied rod-shaped bacteria, peptidoglycan is primarily crosslinked by penicillin-binding proteins (PBPs). However, in mycobacteria, crosslinks formed by L,D-transpeptidases (LDTs) are highly abundant. To elucidate the role of these unusual crosslinks, we characterized Mycobacterium smegmatis cells lacking all LDTs. We find that crosslinks generate by LDTs are required for rod shape maintenance specifically at sites of aging cell wall, a byproduct of polar elongation. Asymmetric polar growth leads to a non-uniform distribution of these two types of crosslinks in a single cell. Consequently, in the absence of LDT-mediated crosslinks, PBP-catalyzed crosslinks become more important. Because of this, Mycobacterium tuberculosis (Mtb) is more rapidly killed using a combination of drugs capable of PBP- and LDT- inhibition. Thus, knowledge about the spatial and genetic relationship between drug targets can be exploited to more effectively treat this pathogen. Most bacteria have a cell wall that protects them and maintains their shape. Many of these organisms make their cell walls from fibers of proteins and sugars, called peptidoglycan. As bacteria grow, peptidoglycan is constantly broken down and reassembled, and in many species, new units of peptidoglycan are added into the sidewall. However, in a group of bacteria called mycobacteria, which cause tuberculosis and other diseases, the units are added at the tips. The peptidoglycan layer is often a successful target for antibiotic treatments. But, drugs that treat tuberculosis do not attack this layer, partly because we know very little about the cell walls of mycobacteria. Here, Baranowski et al. used genetic manipulation and microscopy to study how mycobacteria build their cell wall. The results showed that these bacteria link peptidoglycan units together in an unusual way. In most bacteria, peptidoglycan units are connected by chemical links known as 4-3 crosslinks. This is initially the same in mycobacteria, but as the cell grows and the cell wall expands, these bonds break and so-called 3-3 crosslinks form. In genetically modified bacteria that could not form these 3-3 bonds, the cell wall became brittle and weak, and the bacteria eventually died. These findings could be important for developing new drugs that treat infections caused by mycobacteria. Baranowski et al. demonstrate that a combination of drugs blocking both 4-3 and 3-3 crosslinks is particularly effective at killing the bacterium that causes tuberculosis.
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Affiliation(s)
- Catherine Baranowski
- Department of Immunology and Infectious Disease, Harvard TH Chan School of Public Health, Boston, United States
| | - Michael A Welsh
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States
| | - Lok-To Sham
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States.,Department of Microbiology and Immunology, National University of Singapore, Singapore, Singapore
| | - Haig A Eskandarian
- School of Life Sciences, Swiss Federal Institute of Technology in Lausanne, Lausanne, Switzerland.,School of Engineering, Swiss Federal Institute of Technology in Lausanne, Lausanne, Switzerland
| | - Hoong Chuin Lim
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States
| | - Karen J Kieser
- Department of Immunology and Infectious Disease, Harvard TH Chan School of Public Health, Boston, United States
| | - Jeffrey C Wagner
- Department of Immunology and Infectious Disease, Harvard TH Chan School of Public Health, Boston, United States
| | - John D McKinney
- School of Life Sciences, Swiss Federal Institute of Technology in Lausanne, Lausanne, Switzerland
| | - Georg E Fantner
- School of Engineering, Swiss Federal Institute of Technology in Lausanne, Lausanne, Switzerland
| | - Thomas R Ioerger
- Department of Computer Science and Engineering, Texas A&M University, Texas, United States
| | - Suzanne Walker
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States
| | - Thomas G Bernhardt
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States
| | - Eric J Rubin
- Department of Immunology and Infectious Disease, Harvard TH Chan School of Public Health, Boston, United States.,Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States
| | - E Hesper Rego
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, United States
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14
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Sham LT, Butler EK, Lebar MD, Kahne D, Bernhardt TG, Ruiz N. Bacterial cell wall. MurJ is the flippase of lipid-linked precursors for peptidoglycan biogenesis. Science 2014; 345:220-2. [PMID: 25013077 DOI: 10.1126/science.1254522] [Citation(s) in RCA: 212] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Peptidoglycan (PG) is a polysaccharide matrix that protects bacteria from osmotic lysis. Inhibition of its biogenesis is a proven strategy for killing bacteria with antibiotics. The assembly of PG requires disaccharide-pentapeptide building blocks attached to a polyisoprene lipid carrier called lipid II. Although the stages of lipid II synthesis are known, the identity of the essential flippase that translocates it across the cytoplasmic membrane for PG polymerization is unclear. We developed an assay for lipid II flippase activity and used a chemical genetic strategy to rapidly and specifically block flippase function. We combined these approaches to demonstrate that MurJ is the lipid II flippase in Escherichia coli.
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Affiliation(s)
- Lok-To Sham
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Emily K Butler
- Department of Microbiology, Ohio State University, Columbus, OH 43210, USA
| | - Matthew D Lebar
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Daniel Kahne
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA. Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Thomas G Bernhardt
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA.
| | - Natividad Ruiz
- Department of Microbiology, Ohio State University, Columbus, OH 43210, USA.
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15
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Land AD, Tsui HCT, Kocaoglu O, Vella SA, Shaw SL, Keen SK, Sham LT, Carlson EE, Winkler ME. Requirement of essential Pbp2x and GpsB for septal ring closure in Streptococcus pneumoniae D39. Mol Microbiol 2013; 90:939-55. [PMID: 24118410 DOI: 10.1111/mmi.12408] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2013] [Indexed: 11/29/2022]
Abstract
Bacterial cell shapes are manifestations of programs carried out by multi-protein machines that synthesize and remodel the resilient peptidoglycan (PG) mesh and other polymers surrounding cells. GpsB protein is conserved in low-GC Gram-positive bacteria and is not essential in rod-shaped Bacillus subtilis, where it plays a role in shuttling penicillin-binding proteins (PBPs) between septal and side-wall sites of PG synthesis. In contrast, we report here that GpsB is essential in ellipsoid-shaped, ovococcal Streptococcus pneumoniae (pneumococcus), and depletion of GpsB leads to formation of elongated, enlarged cells containing unsegregated nucleoids and multiple, unconstricted rings of fluorescent-vancomycin staining, and eventual lysis. These phenotypes are similar to those caused by selective inhibition of Pbp2x by methicillin that prevents septal PG synthesis. Dual-protein 2D and 3D-SIM (structured illumination) immunofluorescence microscopy (IFM) showed that GpsB and FtsZ have overlapping, but not identical, patterns of localization during cell division and that multiple, unconstricted rings of division proteins FtsZ, Pbp2x, Pbp1a and MreC are in elongated cells depleted of GpsB. These patterns suggest that GpsB, like Pbp2x, mediates septal ring closure. This first dual-protein 3D-SIM IFM analysis also revealed separate positioning of Pbp2x and Pbp1a in constricting septa, consistent with two separable PG synthesis machines.
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Affiliation(s)
- Adrian D Land
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
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16
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Meisner J, Montero Llopis P, Sham LT, Garner E, Bernhardt TG, Rudner DZ. FtsEX is required for CwlO peptidoglycan hydrolase activity during cell wall elongation in Bacillus subtilis. Mol Microbiol 2013; 89:1069-83. [PMID: 23855774 DOI: 10.1111/mmi.12330] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2013] [Indexed: 11/28/2022]
Abstract
The peptidoglycan (PG) sacculus, a meshwork of polysaccharide strands cross-linked by short peptides, protects bacterial cells against osmotic lysis. To enlarge this covalently closed macromolecule, PG hydrolases must break peptide cross-links in the meshwork to allow insertion of new glycan strands between the existing ones. In the rod-shaped bacterium Bacillus subtilis, cell wall elongation requires two redundant endopeptidases, CwlO and LytE. However, it is not known how these potentially autolytic enzymes are regulated to prevent lethal breaches in the cell wall. Here, we show that the ATP-binding cassette transporter-like FtsEX complex is required for CwlO activity. In Escherichia coli, FtsEX is thought to harness ATP hydrolysis to activate unrelated PG hydrolases during cell division. Consistent with this regulatory scheme, B. subtilis FtsE mutants that are unable to bind or hydrolyse ATP cannot activate CwlO. Finally, we show that in cells depleted of both CwlO and LytE, the PG synthetic machinery continues moving circumferentially until cell lysis, suggesting that cross-link cleavage is not required for glycan strand polymerization. Overall, our data support a model in which the FtsEX complex is a remarkably flexible regulatory module capable of controlling a diverse set of PG hydrolases during growth and division in different organisms.
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Affiliation(s)
- Jeffrey Meisner
- Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA, 02115, USA
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17
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Kocaoglu O, Calvo RA, Sham LT, Cozy LM, Lanning BR, Francis S, Winkler ME, Kearns DB, Carlson EE. Selective penicillin-binding protein imaging probes reveal substructure in bacterial cell division. ACS Chem Biol 2012; 7:1746-53. [PMID: 22909777 DOI: 10.1021/cb300329r] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The peptidoglycan cell wall is a common target for antibiotic therapy, but its structure and assembly are only partially understood. Peptidoglycan synthesis requires a suite of penicillin-binding proteins (PBPs), the individual roles of which are difficult to determine because each enzyme is often dispensable for growth perhaps due to functional redundancy. To address this challenge, we sought to generate tools that would enable selective examination of a subset of PBPs. We designed and synthesized fluorescent and biotin derivatives of the β-lactam-containing antibiotic cephalosporin C. These probes facilitated specific in vivo labeling of active PBPs in both Bacillus subtilis PY79 and an unencapsulated derivative of D39 Streptococcus pneumoniae. Microscopy and gel-based analysis indicated that the cephalosporin C-based probes are more selective than BOCILLIN-FL, a commercially available penicillin V analogue, which labels all PBPs. Dual labeling of live cells performed by saturation of cephalosporin C-susceptible PBPs followed by tagging of the remaining PBP population with BOCILLIN-FL demonstrated that the two sets of PBPs are not co-localized. This suggests that even PBPs that are located at a particular site (e.g., septum) are not all intermixed, but rather that PBP subpopulations are discretely localized. Accordingly, the Ceph C probes represent new tools to explore a subset of PBPs and have the potential to facilitate a deeper understand of the roles of this critical class of proteins.
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Affiliation(s)
- Ozden Kocaoglu
- Departments of †Chemistry, ‡Molecular and Cellular Biochemistry, and §Biology, Indiana University, Bloomington, Indiana
47405, United
States
| | - Rebecca A. Calvo
- Departments of †Chemistry, ‡Molecular and Cellular Biochemistry, and §Biology, Indiana University, Bloomington, Indiana
47405, United
States
| | - Lok-To Sham
- Departments of †Chemistry, ‡Molecular and Cellular Biochemistry, and §Biology, Indiana University, Bloomington, Indiana
47405, United
States
| | - Loralyn M. Cozy
- Departments of †Chemistry, ‡Molecular and Cellular Biochemistry, and §Biology, Indiana University, Bloomington, Indiana
47405, United
States
| | - Bryan R. Lanning
- Departments of †Chemistry, ‡Molecular and Cellular Biochemistry, and §Biology, Indiana University, Bloomington, Indiana
47405, United
States
| | - Samson Francis
- Departments of †Chemistry, ‡Molecular and Cellular Biochemistry, and §Biology, Indiana University, Bloomington, Indiana
47405, United
States
| | - Malcolm E. Winkler
- Departments of †Chemistry, ‡Molecular and Cellular Biochemistry, and §Biology, Indiana University, Bloomington, Indiana
47405, United
States
| | - Daniel B. Kearns
- Departments of †Chemistry, ‡Molecular and Cellular Biochemistry, and §Biology, Indiana University, Bloomington, Indiana
47405, United
States
| | - Erin E. Carlson
- Departments of †Chemistry, ‡Molecular and Cellular Biochemistry, and §Biology, Indiana University, Bloomington, Indiana
47405, United
States
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18
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Sham LT, Tsui HCT, Land AD, Barendt SM, Winkler ME. Recent advances in pneumococcal peptidoglycan biosynthesis suggest new vaccine and antimicrobial targets. Curr Opin Microbiol 2012; 15:194-203. [PMID: 22280885 DOI: 10.1016/j.mib.2011.12.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 12/22/2011] [Accepted: 12/23/2011] [Indexed: 01/09/2023]
Abstract
Streptococcus pneumoniae is a serious human respiratory pathogen that has the capacity to evade capsule-based vaccines and to develop multidrug antibiotic resistance. This review summarizes recent advances in understanding the mechanisms and regulation of peptidoglycan (PG) biosynthesis that result in ellipsoid-shaped, ovococcus Streptococcus cells. New results support a two-state model for septal and peripheral PG synthesis at mid-cell, involvement of essential cell division proteins in PG remodeling, and mid-cell localization of proteins that organize PG biosynthesis and that form the protein translocation apparatus. PG biosynthesis proteins have already turned up as promising vaccine candidates and targets of antibiotics. Properties of several recently characterized proteins that mediate or regulate PG biosynthesis suggest a source of additional targets for therapies against pneumococcus.
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Affiliation(s)
- Lok-To Sham
- Department of Biology, Indiana University Bloomington, Bloomington, IN 47405, United States
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19
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Hsueh YH, Cozy LM, Sham LT, Calvo RA, Gutu AD, Winkler ME, Kearns DB. DegU-phosphate activates expression of the anti-sigma factor FlgM in Bacillus subtilis. Mol Microbiol 2011; 81:1092-108. [PMID: 21736639 DOI: 10.1111/j.1365-2958.2011.07755.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The bacterial flagellum is a complex molecular machine that is assembled by more than 30 proteins and is rotated to propel cells either through liquids or over solid surfaces. Flagellar gene expression is extensively regulated to co-ordinate flagellar assembly in both space and time. In Bacillus subtilis, the proteins of unknown function, SwrA and SwrB, and the alternative sigma factor σ(D) are required to activate expression of the flagellar filament protein, flagellin. Here we determine that in the absence of SwrA and SwrB, the phosphorylated form of the response regulator DegU inhibits σ(D) -dependent gene expression indirectly by binding to the P(flgM) promoter region and activating expression of the anti-sigma factor FlgM. We further demonstrate that DegU-P-dependent activation of FlgM is essential to inhibit flagellin expression when flagellar basal body assembly is disrupted. Regulation of FlgM is poorly understood outside of Salmonella, and differential control of FlgM expression may be a common means of coupling flagellin expression to flagellar assembly.
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Affiliation(s)
- Yi-Huang Hsueh
- Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA
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20
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Tsui HCT, Mukherjee D, Ray VA, Sham LT, Feig AL, Winkler ME. Identification and characterization of noncoding small RNAs in Streptococcus pneumoniae serotype 2 strain D39. J Bacteriol 2010; 192:264-79. [PMID: 19854910 PMCID: PMC2798261 DOI: 10.1128/jb.01204-09] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Accepted: 10/12/2009] [Indexed: 11/20/2022] Open
Abstract
We report a search for small RNAs (sRNAs) in the low-GC, gram-positive human pathogen Streptococcus pneumoniae. Based on bioinformatic analyses by Livny et al. (J. Livny, A. Brencic, S. Lory, and M. K. Waldor, Nucleic Acids Res. 34:3484-3493, 2006), we tested 40 candidates by Northern blotting and confirmed the expression of nine new and one previously reported (CcnA) sRNAs in strain D39. CcnA is one of five redundant sRNAs reported by Halfmann et al. (A. Halfmann, M. Kovacs, R. Hakenbeck, and R. Bruckner, Mol. Microbiol. 66:110-126, 2007) that are positively controlled by the CiaR response regulator. We characterized 3 of these 14 sRNAs: Spd-sr17 (144 nucleotides [nt]; decreased in stationary phase), Spd-sr37 (80 nt; strongly expressed in all growth phases), and CcnA (93 nt; induced by competence stimulatory peptide). Spd-sr17 and CcnA likely fold into structures containing single-stranded regions between hairpin structures, whereas Spd-sr37 forms a base-paired structure. Primer extension mapping and ectopic expression in deletion/insertion mutants confirmed the independent expression of the three sRNAs. Microarray analyses indicated that insertion/deletion mutants in spd-sr37 and ccnA exerted strong cis-acting effects on the transcription of adjacent genes, indicating that these sRNA regions are also cotranscribed in operons. Deletion or overexpression of the three sRNAs did not cause changes in growth, certain stress responses, global transcription, or virulence. Constitutive ectopic expression of CcnA reversed some phenotypes of D39 Delta ciaR mutants, but attempts to link CcnA to -E to comC as a target were inconclusive in ciaR(+) strains. These results show that S. pneumoniae, which lacks known RNA chaperones, expresses numerous sRNAs, but three of these sRNAs do not strongly affect common phenotypes or transcription patterns.
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Affiliation(s)
- Ho-Ching Tiffany Tsui
- Department of Biology, Indiana University—Bloomington, Bloomington, Indiana 47405, Department of Chemistry, Wayne State University, 5101 Cass Ave., Detroit, Michigan 48202
| | - Dhriti Mukherjee
- Department of Biology, Indiana University—Bloomington, Bloomington, Indiana 47405, Department of Chemistry, Wayne State University, 5101 Cass Ave., Detroit, Michigan 48202
| | - Valerie A. Ray
- Department of Biology, Indiana University—Bloomington, Bloomington, Indiana 47405, Department of Chemistry, Wayne State University, 5101 Cass Ave., Detroit, Michigan 48202
| | - Lok-To Sham
- Department of Biology, Indiana University—Bloomington, Bloomington, Indiana 47405, Department of Chemistry, Wayne State University, 5101 Cass Ave., Detroit, Michigan 48202
| | - Andrew L. Feig
- Department of Biology, Indiana University—Bloomington, Bloomington, Indiana 47405, Department of Chemistry, Wayne State University, 5101 Cass Ave., Detroit, Michigan 48202
| | - Malcolm E. Winkler
- Department of Biology, Indiana University—Bloomington, Bloomington, Indiana 47405, Department of Chemistry, Wayne State University, 5101 Cass Ave., Detroit, Michigan 48202
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21
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Ramos-Montañez S, Tsui HCT, Wayne KJ, Morris JL, Peters LE, Zhang F, Kazmierczak KM, Sham LT, Winkler ME. Polymorphism and regulation of the spxB (pyruvate oxidase) virulence factor gene by a CBS-HotDog domain protein (SpxR) in serotype 2 Streptococcus pneumoniae. Mol Microbiol 2007; 67:729-46. [PMID: 18179423 DOI: 10.1111/j.1365-2958.2007.06082.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
spxB-encoded pyruvate oxidase is a major virulence factor of Streptococcus pneumoniae. During aerobic growth, SpxB synthesizes H2O2 and acetyl phosphate, which play roles in metabolism, signalling, and oxidative stress. We report here the first cis- and trans-acting regulatory elements for spxB transcription. These elements were identified in a genetic screen for spontaneous mutations that caused colonies of strain D39 to change from a semitransparent to an opaque appearance. Six of the seven opaque colonies recovered (frequency approximately 3 x 10(-5)) were impaired for SpxB function or expression. Two mutations changed amino acids in SpxB likely required for cofactor or subunit binding. One mutation defined a cis-acting adjacent direct repeat required for optimal spxB transcription. The other three spontaneous mutations created the same frameshift near the start of the trans-acting spxR regulatory gene. The SpxR protein contains helix-turn-helix, CBS and HotDog domains implicated in binding DNA, adenosyl compounds, and CoA-containing compounds respectively, and suggest that SpxR positively regulates spxB transcription in response to energy and metabolic state. Microarray analyses unexpectedly demonstrated that SpxR also positively regulates the strH exoglycosidase gene, which, like spxB, has been implicated in colonization. Finally, SpxR is required for full virulence in a murine model of infection.
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