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Zhang P, Liu Z. Structural insights into the transporting and catalyzing mechanism of DltB in LTA D-alanylation. Nat Commun 2024; 15:3404. [PMID: 38649359 PMCID: PMC11035591 DOI: 10.1038/s41467-024-47783-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 04/12/2024] [Indexed: 04/25/2024] Open
Abstract
DltB, a model member of the Membrane-Bound O-AcylTransferase (MBOAT) superfamily, plays a crucial role in D-alanylation of the lipoteichoic acid (LTA), a significant component of the cell wall of gram-positive bacteria. This process stabilizes the cell wall structure, influences bacterial virulence, and modulates the host immune response. Despite its significance, the role of DltB is not well understood. Through biochemical analysis and cryo-EM imaging, we discover that Streptococcus thermophilus DltB forms a homo-tetramer on the cell membrane. We further visualize DltB in an apo form, in complex with DltC, and in complex with its inhibitor amsacrine (m-AMSA). Each tetramer features a central hole. The C-tunnel of each protomer faces the intratetramer interface and provides access to the periphery membrane. Each protomer binds a DltC without changing the tetrameric organization. A phosphatidylglycerol (PG) molecule in the substrate-binding site may serve as an LTA carrier. The inhibitor m-AMSA bound to the L-tunnel of each protomer blocks the active site. The tetrameric organization of DltB provides a scaffold for catalyzing D-alanyl transfer and regulating the channel opening and closing. Our findings unveil DltB's dual function in the D-alanylation pathway, and provide insight for targeting DltB as a anti-virulence antibiotic.
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Affiliation(s)
- Pingfeng Zhang
- Cancer Center, Renmin Hospital of Wuhan University, Wuhan, China.
| | - Zheng Liu
- Kobilka Institute of Innovative Drug Discovery, School of Medicine, The Chinese University of Hong Kong, Shenzhen, Shenzhen, China.
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2
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Modi SK, Gaur S, Sengupta M, Singh MS. Mechanistic insights into nanoparticle surface-bacterial membrane interactions in overcoming antibiotic resistance. Front Microbiol 2023; 14:1135579. [PMID: 37152753 PMCID: PMC10160668 DOI: 10.3389/fmicb.2023.1135579] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 03/30/2023] [Indexed: 05/09/2023] Open
Abstract
Antimicrobial Resistance (AMR) raises a serious concern as it contributes to the global mortality by 5 million deaths per year. The overall impact pertaining to significant membrane changes, through broad spectrum drugs have rendered the bacteria resistant over the years. The economic expenditure due to increasing drug resistance poses a global burden on healthcare community and must be dealt with immediate effect. Nanoparticles (NP) have demonstrated inherent therapeutic potential or can serve as nanocarriers of antibiotics against multidrug resistant (MDR) pathogens. These carriers can mask the antibiotics and help evade the resistance mechanism of the bacteria. The targeted delivery can be fine-tuned through surface functionalization of Nanocarriers using aptamers, antibodies etc. This review covers various molecular mechanisms acquired by resistant bacteria towards membrane modification. Mechanistic insight on 'NP surface-bacterial membrane' interactions are crucial in deciding the role of NP as therapeutic. Finally, we highlight the potential accessible membrane targets for designing smart surface-functionalized nanocarriers which can act as bacteria-targeted robots over the existing clinically available antibiotics. As the bacterial strains around us continue to evolve into resistant versions, nanomedicine can offer promising and alternative tools in overcoming AMR.
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Affiliation(s)
- Suraj Kumar Modi
- Department of Biotechnology, Bennett University, Greater Noida, Uttar Pradesh, India
- Centre of Excellence for Nanosensors and Nanomedicine, Bennett University, Greater Noida, Uttar Pradesh, India
| | - Smriti Gaur
- Department of Biotechnology, Bennett University, Greater Noida, Uttar Pradesh, India
| | - Mrittika Sengupta
- Department of Biotechnology, Bennett University, Greater Noida, Uttar Pradesh, India
- Centre of Excellence for Nanosensors and Nanomedicine, Bennett University, Greater Noida, Uttar Pradesh, India
- Mrittika Sengupta, ;
| | - Manu Smriti Singh
- Department of Biotechnology, Bennett University, Greater Noida, Uttar Pradesh, India
- Centre of Excellence for Nanosensors and Nanomedicine, Bennett University, Greater Noida, Uttar Pradesh, India
- *Correspondence: Manu Smriti Singh, ;
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3
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Liu X, An L, Ren S, Zhou Y, Peng W. Comparative Proteomic Analysis Reveals Antibacterial Mechanism of Patrinia scabiosaefolia Against Methicillin Resistant Staphylococcus epidermidis. Infect Drug Resist 2022; 15:883-893. [PMID: 35281570 PMCID: PMC8912936 DOI: 10.2147/idr.s350715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 01/21/2022] [Indexed: 11/23/2022] Open
Abstract
Purpose As a kind of opportunist pathogen, Staphylococcus epidermidis (MRSE) can cause nosocomial infections and easily evolve into resistant bacteria. Among these, methicillin-resistant Staphylococcus epidermidis (MRSE) exhibit significantly higher rates. Our previous study showed that Patrinia scabiosaefolia (PS) possessed strong antibacterial activity against MRSE. However, the mechanism of PS against MRSE is not clear. Methods Here, a tandem mass tag-based (TMT) proteomic analysis was performed to elucidate the potential mechanism of PS against MRSE. We compared the differential expression proteins of MRSE under PS stress. Results Based on a fold change of >1.2 or < 1/1.2 (with p value set at <0.05), a total of 248 proteins (128 up-regulated proteins, 120 down-regulated proteins) were identified. Bioinformatic analysis showed that proteins including arginine deiminase (arcA), ornithine carbamoyltransferase (arcB) and carbamate kinase (arcC), serine–tRNA ligase (serS), phenylalanine–tRNA ligase beta and subunit (pheT), DltD (dlt), d-alanyl carrier protein (dlt), accumulation-associated protein (SasG), serine-aspartate repeat-containing protein C (SdrC) and hemin transport system permease protein HrtB (VraG) played important roles in mechanism of PS against MRSE. Conclusion In summary, these results indicated that arginine deiminase pathway (ADI) pathway, protein synthesis, cell wall synthesis, biofilm formation and uptake of iron were related to mechanisms of PS against MRSE. Our findings provide an insight into the the mechanism of PS against MRSE, and may be valuable in offering new targets to develop more anti-MRSE drugs.
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Affiliation(s)
- Xin Liu
- College of Basic Medicine, Guizhou University of Traditional Chinese Medicine, Guiyang, Guizhou, 550025, People’s Republic of China
- Correspondence: Xin Liu, College of Basic Medicine, Guizhou University of Traditional Chinese Medicine, Guiyang, Guizhou, 550025, People’s Republic of China, Tel +8618886056643, Email
| | - Lili An
- Dermatology Department, The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, Guizhou, 550025, People’s Republic of China
| | - Shuaijun Ren
- Dermatology Department, The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, Guizhou, 550025, People’s Republic of China
| | - Yonghui Zhou
- College of Basic Medicine, Guizhou University of Traditional Chinese Medicine, Guiyang, Guizhou, 550025, People’s Republic of China
| | - Wei Peng
- College of Basic Medicine, Guizhou University of Traditional Chinese Medicine, Guiyang, Guizhou, 550025, People’s Republic of China
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4
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Zhang R, Shebes MA, Kho K, Scaffidi SJ, Meredith TC, Yu W. Spatial regulation of protein A in Staphylococcus aureus. Mol Microbiol 2021; 116:589-605. [PMID: 33949015 DOI: 10.1111/mmi.14734] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 04/29/2021] [Accepted: 04/30/2021] [Indexed: 12/31/2022]
Abstract
Surface proteins of Staphylococcus aureus play vital roles in bacterial physiology and pathogenesis. Recent work suggests that surface proteins are spatially regulated by a YSIRK/GXXS signal peptide that promotes cross-wall targeting at the mid-cell, though the mechanisms remain unclear. We previously showed that protein A (SpA), a YSIRK/GXXS protein and key staphylococcal virulence factor, mis-localizes in a ltaS mutant deficient in lipoteichoic acid (LTA) production. Here, we identified that SpA contains another cross-wall targeting signal, the LysM domain, which, in addition to the YSIRK/GXXS signal peptide, significantly enhances SpA cross-wall targeting. We show that LTA synthesis, but not LtaS, is required for SpA septal anchoring and cross-wall deposition. Interestingly, LTA is predominantly found at the peripheral cell membrane and is diminished at the septum of dividing staphylococcal cells, suggesting a restriction mechanism for SpA septal localization. Finally, we show that D-alanylation of LTA abolishes SpA cross-wall deposition by disrupting SpA distribution in the peptidoglycan layer without altering SpA septal anchoring. Our study reveals that multiple factors contribute to the spatial regulation and cross-wall targeting of SpA via different mechanisms, which coordinately ensures efficient incorporation of surface proteins into the growing peptidoglycan during the cell cycle.
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Affiliation(s)
- Ran Zhang
- Department of Cell Biology, Microbiology and Molecular Biology (CMMB), University of South Florida, Tampa, FL, USA
| | - Mac A Shebes
- Department of Cell Biology, Microbiology and Molecular Biology (CMMB), University of South Florida, Tampa, FL, USA
| | - Kelvin Kho
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Salvatore J Scaffidi
- Department of Cell Biology, Microbiology and Molecular Biology (CMMB), University of South Florida, Tampa, FL, USA
| | - Timothy C Meredith
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Wenqi Yu
- Department of Cell Biology, Microbiology and Molecular Biology (CMMB), University of South Florida, Tampa, FL, USA
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5
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Wambui J, Eshwar AK, Aalto-Araneda M, Pöntinen A, Stevens MJA, Njage PMK, Tasara T. The Analysis of Field Strains Isolated From Food, Animal and Clinical Sources Uncovers Natural Mutations in Listeria monocytogenes Nisin Resistance Genes. Front Microbiol 2020; 11:549531. [PMID: 33123101 PMCID: PMC7574537 DOI: 10.3389/fmicb.2020.549531] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 09/02/2020] [Indexed: 12/19/2022] Open
Abstract
Nisin is a commonly used bacteriocin for controlling spoilage and pathogenic bacteria in food products. Strains possessing high natural nisin resistance that reduce or increase the potency of this bacteriocin against Listeria monocytogenes have been described. Our study sought to gather more insights into nisin resistance mechanisms in natural L. monocytogenes populations by examining a collection of 356 field strains that were isolated from different foods, food production environments, animals and human infections. A growth curve analysis-based approach was used to access nisin inhibition levels and assign the L. monocytogenes strains into three nisin response phenotypic categories; resistant (66%), intermediate (26%), and sensitive (8%). Using this categorization isolation source, serotype, genetic lineage, clonal complex (CC) and strain-dependent natural variation in nisin phenotypic resistance among L. monocytogenes field strains was revealed. Whole genome sequence analysis and comparison of high nisin resistant and sensitive strains led to the identification of new naturally occurring mutations in nisin response genes associated with increased nisin resistance and sensitivity in this bacterium. Increased nisin resistance was detected in strains harboring RsbUG77S and PBPB3V240F amino acid substitution mutations, which also showed increased detergent stress resistance as well as increased virulence in a zebra fish infection model. On the other hand, increased natural nisin sensitivity was detected among strains with mutations in sigB, vir, and dlt operons that also showed increased lysozyme sensitivity and lower virulence. Overall, our study identified naturally selected mutations involving pbpB3 (lm0441) as well as sigB, vir, and dlt operon genes that are associated with intrinsic nisin resistance in L. monocytogenes field strains recovered from various food and human associated sources. Finally, we show that combining growth parameter-based phenotypic analysis and genome sequencing is an effective approach that can be useful for the identification of novel nisin response associated genetic variants among L. monocytogenes field strains.
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Affiliation(s)
- Joseph Wambui
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Athmanya K Eshwar
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Mariella Aalto-Araneda
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Anna Pöntinen
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Marc J A Stevens
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Patrick M K Njage
- Research Group for Genomic Epidemiology, Division for Global Surveillance, National Food Institute, Technical University of Denmark, Kengens Lyngby, Denmark
| | - Taurai Tasara
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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Revilla-Guarinos A, Zhang Q, Loderer C, Alcántara C, Müller A, Rahnamaeian M, Vilcinskas A, Gebhard S, Zúñiga M, Mascher T. ABC Transporter DerAB of Lactobacillus casei Mediates Resistance against Insect-Derived Defensins. Appl Environ Microbiol 2020; 86:e00818-20. [PMID: 32414796 PMCID: PMC7357469 DOI: 10.1128/aem.00818-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 05/09/2020] [Indexed: 01/28/2023] Open
Abstract
Bce-like systems mediate resistance against antimicrobial peptides in Firmicutes bacteria. Lactobacillus casei BL23 encodes an "orphan" ABC transporter that, based on homology to BceAB-like systems, was proposed to contribute to antimicrobial peptide resistance. A mutant lacking the permease subunit was tested for sensitivity against a collection of peptides derived from bacteria, fungi, insects, and humans. Our results show that the transporter specifically conferred resistance against insect-derived cysteine-stabilized αβ defensins, and it was therefore renamed DerAB for defensin resistance ABC transporter. Surprisingly, cells lacking DerAB showed a marked increase in resistance against the lantibiotic nisin. This could be explained by significantly increased expression of the antimicrobial peptide resistance determinants regulated by the Bce-like systems PsdRSAB (formerly module 09) and ApsRSAB (formerly module 12). Bacterial two-hybrid studies in Escherichia coli showed that DerB could interact with proteins of the sensory complex in the Psd resistance system. We therefore propose that interaction of DerAB with this complex in the cell creates signaling interference and reduces the cell's potential to mount an effective nisin resistance response. In the absence of DerB, this negative interference is relieved, leading to the observed hyperactivation of the Psd module and thus increased resistance to nisin. Our results unravel the function of a previously uncharacterized Bce-like orphan resistance transporter with pleiotropic biological effects on the cell.IMPORTANCE Antimicrobial peptides (AMPs) play an important role in suppressing the growth of microorganisms. They can be produced by bacteria themselves-to inhibit competitors-but are also widely distributed in higher eukaryotes, including insects and mammals, where they form an important component of innate immunity. In low-GC-content Gram-positive bacteria, BceAB-like transporters play a crucial role in AMP resistance but have so far been primarily associated with interbacterial competition. Here, we show that the orphan transporter DerAB from the lactic acid bacterium Lactobacillus casei is crucial for high-level resistance against insect-derived AMPs. It therefore represents an important mechanism for interkingdom defense. Furthermore, our results support a signaling interference from DerAB on the PsdRSAB module that might prevent the activation of a full nisin response. The Bce modules from L. casei BL23 illustrate a biological paradox in which the intrinsic nisin detoxification potential only arises in the absence of a defensin-specific ABC transporter.
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Affiliation(s)
| | - Qian Zhang
- Institut für Mikrobiologie, Technische Universität Dresden, Dresden, Germany
| | - Christoph Loderer
- Institut für Mikrobiologie, Technische Universität Dresden, Dresden, Germany
| | - Cristina Alcántara
- Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Valencia, Spain
| | - Ariane Müller
- Institut für Zoologie, Technische Universität Dresden, Dresden, Germany
| | - Mohammad Rahnamaeian
- Fraunhofer Institute for Molecular Biology and Applied Ecology, Department of Bioresources, Giessen, Germany
| | - Andreas Vilcinskas
- Fraunhofer Institute for Molecular Biology and Applied Ecology, Department of Bioresources, Giessen, Germany
- Institute for Insect Biotechnology, Justus Liebig University Giessen, Giessen, Germany
| | - Susanne Gebhard
- Department of Biology and Biochemistry, Milner Centre for Evolution, University of Bath, United Kingdom
| | - Manuel Zúñiga
- Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Valencia, Spain
| | - Thorsten Mascher
- Institut für Mikrobiologie, Technische Universität Dresden, Dresden, Germany
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7
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Mechanisms of bactericidal action and resistance of polymyxins for Gram-positive bacteria. Appl Microbiol Biotechnol 2020; 104:3771-3780. [PMID: 32157424 DOI: 10.1007/s00253-020-10525-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/25/2020] [Accepted: 03/03/2020] [Indexed: 10/24/2022]
Abstract
Polymyxins are cationic antimicrobial peptides used as the last-line therapy to treat multidrug-resistant Gram-negative bacterial infections. The bactericidal activity of polymyxins against Gram-negative bacteria relies on the electrostatic interaction between the positively charged polymyxins and the negatively charged lipid A of lipopolysaccharide (LPS). Given that Gram-positive bacteria lack an LPS-containing outer membrane, it is generally acknowledged that polymyxins are less active against Gram-positive bacteria. However, Gram-positive bacteria produce negatively charged teichoic acids, which may act as the target of polymyxins. More and more studies suggest that polymyxins have potential as a treatment for Gram-positive bacterial infection. This mini-review discusses recent advances in the mechanism of the antibacterial activity and resistance of polymyxins in Gram-positive bacteria.Key Points• Teichoic acids play a key role in the action of polymyxins on Gram-positive bacteria.• Polymyxin kills Gram-positive bacteria by disrupting cell surface and oxidative damage.• Modification of teichoic acids and phospholipids contributes to polymyxin resistance in Gram-positive bacteria.• Polymyxins have potential as a treatment for Gram-positive bacterial infection.
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Abstract
Membrane-bound O-acyltransferases (MBOATs) are a superfamily of integral transmembrane enzymes that are found in all kingdoms of life1. In bacteria, MBOATs modify protective cell-surface polymers. In vertebrates, some MBOAT enzymes-such as acyl-coenzyme A:cholesterol acyltransferase and diacylglycerol acyltransferase 1-are responsible for lipid biosynthesis or phospholipid remodelling2,3. Other MBOATs, including porcupine, hedgehog acyltransferase and ghrelin acyltransferase, catalyse essential lipid modifications of secreted proteins such as Wnt, hedgehog and ghrelin, respectively4-10. Although many MBOAT proteins are important drug targets, little is known about their molecular architecture and functional mechanisms. Here we present crystal structures of DltB, an MBOAT responsible for the D-alanylation of cell-wall teichoic acid in Gram-positive bacteria11-16, both alone and in complex with the D-alanyl donor protein DltC. DltB contains a ring of 11 peripheral transmembrane helices, which shield a highly conserved extracellular structural funnel extending into the middle of the lipid bilayer. The conserved catalytic histidine residue is located at the bottom of this funnel and is connected to the intracellular DltC through a narrow tunnel. Mutation of either the catalytic histidine or the DltC-binding site of DltB abolishes the D-alanylation of lipoteichoic acid and sensitizes the Gram-positive bacterium Bacillus subtilis to cell-wall stress, which suggests cross-membrane catalysis involving the tunnel. Structure-guided sequence comparison among DltB and vertebrate MBOATs reveals a conserved structural core and suggests that MBOATs from different organisms have similar catalytic mechanisms. Our structures provide a template for understanding structure-function relationships in MBOATs and for developing therapeutic MBOAT inhibitors.
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Fong R, Kajihara K, Chen M, Hotzel I, Mariathasan S, Hazenbos WL, Lupardus PJ. Structural investigation of human S. aureus-targeting antibodies that bind wall teichoic acid. MAbs 2018; 10:979-991. [PMID: 30102105 PMCID: PMC6204806 DOI: 10.1080/19420862.2018.1501252] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are a growing health threat worldwide. Efforts to identify novel antibodies that target S. aureus cell surface antigens are a promising direction in the development of antibiotics that can halt MRSA infection. We biochemically and structurally characterized three patient-derived MRSA-targeting antibodies that bind to wall teichoic acid (WTA), which is a polyanionic surface glycopolymer. In S. aureus, WTA exists in both α- and β-forms, based on the stereochemistry of attachment of a N-acetylglucosamine residue to the repeating phosphoribitol sugar unit. We identified a panel of antibodies cloned from human patients that specifically recognize the α or β form of WTA, and can bind with high affinity to pathogenic wild-type strains of S. aureus bacteria. To investigate how the β-WTA specific antibodies interact with their target epitope, we determined the X-ray crystal structures of the three β-WTA specific antibodies, 4462, 4497, and 6078 (Protein Data Bank IDs 6DWI, 6DWA, and 6DW2, respectively), bound to a synthetic WTA epitope. These structures reveal that all three of these antibodies, while utilizing distinct antibody complementarity-determining region sequences and conformations to interact with β-WTA, fulfill two recognition principles: binding to the β-GlcNAc pyranose core and triangulation of WTA phosphate residues with polar contacts. These studies reveal the molecular basis for targeting a unique S. aureus cell surface epitope and highlight the power of human patient-based antibody discovery techniques for finding novel pathogen-targeting therapeutics.
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Affiliation(s)
- Rina Fong
- Department of Structural Biology, Genentech, South San Francisco, CA, USA,Departments of Infectious Diseases, Genentech, South San Francisco, CA, USA,Departments of Antibody Engineering, Genentech, South San Francisco, CA, USA
| | - Kimberly Kajihara
- Department of Structural Biology, Genentech, South San Francisco, CA, USA,Departments of Infectious Diseases, Genentech, South San Francisco, CA, USA,Departments of Antibody Engineering, Genentech, South San Francisco, CA, USA
| | - Matthew Chen
- Department of Structural Biology, Genentech, South San Francisco, CA, USA,Departments of Infectious Diseases, Genentech, South San Francisco, CA, USA,Departments of Antibody Engineering, Genentech, South San Francisco, CA, USA
| | - Isidro Hotzel
- Department of Structural Biology, Genentech, South San Francisco, CA, USA,Departments of Infectious Diseases, Genentech, South San Francisco, CA, USA,Departments of Antibody Engineering, Genentech, South San Francisco, CA, USA
| | - Sanjeev Mariathasan
- Department of Structural Biology, Genentech, South San Francisco, CA, USA,Departments of Infectious Diseases, Genentech, South San Francisco, CA, USA,Departments of Antibody Engineering, Genentech, South San Francisco, CA, USA
| | - Wouter L.W. Hazenbos
- Department of Structural Biology, Genentech, South San Francisco, CA, USA,Departments of Infectious Diseases, Genentech, South San Francisco, CA, USA,Departments of Antibody Engineering, Genentech, South San Francisco, CA, USA
| | - Patrick J. Lupardus
- Department of Structural Biology, Genentech, South San Francisco, CA, USA,Departments of Infectious Diseases, Genentech, South San Francisco, CA, USA,Departments of Antibody Engineering, Genentech, South San Francisco, CA, USA,CONTACT Patrick J. Lupardus Department of Structural Biology, Genentech, South San Francisco, CA, USA
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Kamar R, Réjasse A, Jéhanno I, Attieh Z, Courtin P, Chapot-Chartier MP, Nielsen-Leroux C, Lereclus D, El Chamy L, Kallassy M, Sanchis-Borja V. DltX of Bacillus thuringiensis Is Essential for D-Alanylation of Teichoic Acids and Resistance to Antimicrobial Response in Insects. Front Microbiol 2017; 8:1437. [PMID: 28824570 PMCID: PMC5541007 DOI: 10.3389/fmicb.2017.01437] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 07/14/2017] [Indexed: 11/13/2022] Open
Abstract
The dlt operon of Gram-positive bacteria is required for the incorporation of D-alanine esters into cell wall-associated teichoic acids (TAs). Addition of D-alanine to TAs reduces the negative charge of the cell envelope thereby preventing cationic antimicrobial peptides (CAMPs) from reaching their target of action on the bacterial surface. In most gram-positive bacteria, this operon consists of five genes dltXABCD but the involvement of the first ORF (dltX) encoding a small protein of unknown function, has never been investigated. The aim of this study was to establish whether this protein is involved in the D-alanylation process in Bacillus thuringiensis. We, therefore constructed an in frame deletion mutant of dltX, without affecting the expression of the other genes of the operon. The growth characteristics of the dltX mutant and those of the wild type strain were similar under standard in vitro conditions. However, disruption of dltX drastically impaired the resistance of B. thuringiensis to CAMPs and significantly attenuated its virulence in two insect species. Moreover, high-performance liquid chromatography studies showed that the dltX mutant was devoid of D-alanine, and electrophoretic mobility measurements indicated that the cells carried a higher negative surface charge. Scanning electron microscopy experiments showed morphological alterations of these mutant bacteria, suggesting that depletion of D-alanine from TAs affects cell wall structure. Our findings suggest that DltX is essential for the incorporation of D-alanyl esters into TAs. Therefore, DltX plays a direct role in the resistance to CAMPs, thus contributing to the survival of B. thuringiensis in insects. To our knowledge, this work is the first report examining the involvement of dltX in the D-alanylation of TAs.
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Affiliation(s)
- Rita Kamar
- INRA, UMR1319 MicalisJouy-en-Josas, France.,AgroParisTech, UMR MicalisJouy-en-Josas, France.,Laboratoire de Génétique de la Drosophile et Virulence Microbienne, Université Saint-JosephBeirut, Lebanon
| | - Agnès Réjasse
- INRA, UMR1319 MicalisJouy-en-Josas, France.,AgroParisTech, UMR MicalisJouy-en-Josas, France
| | - Isabelle Jéhanno
- INRA, UMR1319 MicalisJouy-en-Josas, France.,AgroParisTech, UMR MicalisJouy-en-Josas, France
| | - Zaynoun Attieh
- Laboratoire de Génétique de la Drosophile et Virulence Microbienne, Université Saint-JosephBeirut, Lebanon
| | - Pascal Courtin
- INRA, UMR1319 MicalisJouy-en-Josas, France.,AgroParisTech, UMR MicalisJouy-en-Josas, France
| | | | | | - Didier Lereclus
- INRA, UMR1319 MicalisJouy-en-Josas, France.,AgroParisTech, UMR MicalisJouy-en-Josas, France
| | - Laure El Chamy
- Laboratoire de Génétique de la Drosophile et Virulence Microbienne, Université Saint-JosephBeirut, Lebanon
| | - Mireille Kallassy
- Laboratoire de Génétique de la Drosophile et Virulence Microbienne, Université Saint-JosephBeirut, Lebanon
| | - Vincent Sanchis-Borja
- INRA, UMR1319 MicalisJouy-en-Josas, France.,AgroParisTech, UMR MicalisJouy-en-Josas, France
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11
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Zhai Q, Xiao Y, Zhao J, Tian F, Zhang H, Narbad A, Chen W. Identification of key proteins and pathways in cadmium tolerance of Lactobacillus plantarum strains by proteomic analysis. Sci Rep 2017; 7:1182. [PMID: 28446769 PMCID: PMC5430759 DOI: 10.1038/s41598-017-01180-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/22/2017] [Indexed: 12/20/2022] Open
Abstract
Our previous study confirmed the protective potential of Lactobacillus plantarum (L. plantarum) strains in alleviation of cadmium (Cd) toxicity in vivo and demonstrated that the observed protection largely depended on the tolerance of the strains to Cd-induced stress. It was also observed that there were significant intra-species differences in Cd tolerance of L. plantarum strains. In this study, we investigated the mechanism of Cd induced stress response of L. plantarum strains using the isobaric tags for relative and absolute quantitation (iTRAQ) based comparative proteomics. L. plantarum CCFM8610 (strongly resistant to Cd) and L. plantarum CCFM191 (sensitive to Cd) were selected as target strains, and their proteomic profiles in the presence and absence of Cd exposure were compared. We propose that the underlying mechanism of the exceptional Cd tolerance of CCFM8610 may be attributed to the following: (a) a specific energy-conservation survival mode; (b) mild induction of its cellular defense and repair system; (c) an enhanced biosynthesis of hydrophobic amino acids in response to Cd; (d) inherent superior Cd binding ability and effective cell wall biosynthesis ability; (e) a tight regulation on ion transport; (f) several key proteins, including prophage P2b protein 18, CadA, mntA and lp_3327.
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Affiliation(s)
- Qixiao Zhai
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, People's Republic of China.,UK-China Joint Centre on Probiotic Bacteria, Norwich, NR4 7UA, UK
| | - Yue Xiao
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, People's Republic of China
| | - Jianxin Zhao
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, People's Republic of China
| | - Fengwei Tian
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, People's Republic of China.,UK-China Joint Centre on Probiotic Bacteria, Norwich, NR4 7UA, UK
| | - Hao Zhang
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, People's Republic of China.,UK-China Joint Centre on Probiotic Bacteria, Norwich, NR4 7UA, UK
| | - Arjan Narbad
- UK-China Joint Centre on Probiotic Bacteria, Norwich, NR4 7UA, UK.,Gut Health and Food Safety Programme, Institute of Food Research, Norwich, NR4 7UA, United Kingdom
| | - Wei Chen
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, People's Republic of China. .,UK-China Joint Centre on Probiotic Bacteria, Norwich, NR4 7UA, UK. .,Beijing Innovation Centre of Food Nutrition and Human Health, Beijing Technology & Business University, Beijing, 100048, People's Republic of China.
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12
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Monedero V, Revilla-Guarinos A, Zúñiga M. Physiological Role of Two-Component Signal Transduction Systems in Food-Associated Lactic Acid Bacteria. ADVANCES IN APPLIED MICROBIOLOGY 2017; 99:1-51. [PMID: 28438266 DOI: 10.1016/bs.aambs.2016.12.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Two-component systems (TCSs) are widespread signal transduction pathways mainly found in bacteria where they play a major role in adaptation to changing environmental conditions. TCSs generally consist of sensor histidine kinases that autophosphorylate in response to a specific stimulus and subsequently transfer the phosphate group to their cognate response regulators thus modulating their activity, usually as transcriptional regulators. In this review we present the current knowledge on the physiological role of TCSs in species of the families Lactobacillaceae and Leuconostocaceae of the group of lactic acid bacteria (LAB). LAB are microorganisms of great relevance for health and food production as the group spans from starter organisms to pathogens. Whereas the role of TCSs in pathogenic LAB (most of them belonging to the family Streptococcaceae) has focused the attention, the roles of TCSs in commensal LAB, such as most species of Lactobacillaceae and Leuconostocaceae, have been somewhat neglected. However, evidence available indicates that TCSs are key players in the regulation of the physiology of these bacteria. The first studies in food-associated LAB showed the involvement of some TCSs in quorum sensing and production of bacteriocins, but subsequent studies have shown that TCSs participate in other physiological processes, such as stress response, regulation of nitrogen metabolism, regulation of malate metabolism, and resistance to antimicrobial peptides, among others.
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Affiliation(s)
- Vicente Monedero
- Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Paterna, Spain
| | | | - Manuel Zúñiga
- Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Paterna, Spain
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13
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Steinbuch KB, Fridman M. Mechanisms of resistance to membrane-disrupting antibiotics in Gram-positive and Gram-negative bacteria. MEDCHEMCOMM 2016. [DOI: 10.1039/c5md00389j] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A diverse repertoire of mechanisms has evolved to confer resistance to bacterial membrane disrupting antimicrobial cationic amphiphiles.
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Affiliation(s)
- Kfir B. Steinbuch
- School of Chemistry
- Beverly Raymond Sackler Faculty of Exact Sciences
- Tel Aviv University
- Tel Aviv
- Israel
| | - Micha Fridman
- School of Chemistry
- Beverly Raymond Sackler Faculty of Exact Sciences
- Tel Aviv University
- Tel Aviv
- Israel
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14
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Flores-Kim J, Darwin AJ. Regulation of bacterial virulence gene expression by cell envelope stress responses. Virulence 2015; 5:835-51. [PMID: 25603429 DOI: 10.4161/21505594.2014.965580] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The bacterial cytoplasm lies within a multilayered envelope that must be protected from internal and external hazards. This protection is provided by cell envelope stress responses (ESRs), which detect threats and reprogram gene expression to ensure survival. Pathogens frequently need these ESRs to survive inside the host, where their envelopes face dangerous environmental changes and attack from antimicrobial molecules. In addition, some virulence genes have become integrated into ESR regulons. This might be because these genes can protect the cell envelope from damage by host molecules, or it might help ESRs to reduce stress by moderating the assembly of virulence factors within the envelope. Alternatively, it could simply be a mechanism to coordinate the induction of virulence gene expression with entry into the host. Here, we briefly describe some of the bacterial ESRs, followed by examples where they control virulence gene expression in both Gram-negative and Gram-positive pathogens.
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Key Words
- BFP, bundle-forming pilus
- CAMP, cationic antimicrobial peptide
- CF, cystic fibrosis
- ECF, extracytoplasmic function
- EPEC, enteropathogenic E. coli
- ESR, envelope stress response
- HMV, hypermucoviscosity
- IM, inner membrane
- LPS, lipopolysaccharide
- LTA, lipoteichoic acids
- OM, outer membrane
- OMP, outer membrane protein
- PG, phosphatidylglycerol
- T(2/3/4)SS, type II/III/IV secretion system
- UPEC, uropathogenic E. coli
- WTA, wall teichoic acids
- antimicrobial peptide
- bacterial pathogens
- cell envelope
- gene regulation
- peptidoglycan
- phospholipid
- stress response
- teichoic acid
- virulence gene
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Affiliation(s)
- Josué Flores-Kim
- a Department of Microbiology ; New York University School of Medicine ; New York , NY USA
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15
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Nawrocki KL, Crispell EK, McBride SM. Antimicrobial Peptide Resistance Mechanisms of Gram-Positive Bacteria. Antibiotics (Basel) 2014; 3:461-92. [PMID: 25419466 PMCID: PMC4239024 DOI: 10.3390/antibiotics3040461] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 09/25/2014] [Accepted: 09/28/2014] [Indexed: 01/09/2023] Open
Abstract
Antimicrobial peptides, or AMPs, play a significant role in many environments as a tool to remove competing organisms. In response, many bacteria have evolved mechanisms to resist these peptides and prevent AMP-mediated killing. The development of AMP resistance mechanisms is driven by direct competition between bacterial species, as well as host and pathogen interactions. Akin to the number of different AMPs found in nature, resistance mechanisms that have evolved are just as varied and may confer broad-range resistance or specific resistance to AMPs. Specific mechanisms of AMP resistance prevent AMP-mediated killing against a single type of AMP, while broad resistance mechanisms often lead to a global change in the bacterial cell surface and protect the bacterium from a large group of AMPs that have similar characteristics. AMP resistance mechanisms can be found in many species of bacteria and can provide a competitive edge against other bacterial species or a host immune response. Gram-positive bacteria are one of the largest AMP producing groups, but characterization of Gram-positive AMP resistance mechanisms lags behind that of Gram-negative species. In this review we present a summary of the AMP resistance mechanisms that have been identified and characterized in Gram-positive bacteria. Understanding the mechanisms of AMP resistance in Gram-positive species can provide guidelines in developing and applying AMPs as therapeutics, and offer insight into the role of resistance in bacterial pathogenesis.
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Affiliation(s)
- Kathryn L Nawrocki
- Department of Microbiology and Immunology, Emory University School of Medicine, 1510 Clifton Rd, Atlanta, GA 30322, USA; (K.L.N.); (E.K.C.)
| | - Emily K Crispell
- Department of Microbiology and Immunology, Emory University School of Medicine, 1510 Clifton Rd, Atlanta, GA 30322, USA; (K.L.N.); (E.K.C.)
| | - Shonna M McBride
- Department of Microbiology and Immunology, Emory University School of Medicine, 1510 Clifton Rd, Atlanta, GA 30322, USA; (K.L.N.); (E.K.C.)
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16
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Huang Q, Fei J, Yu HJ, Gou YB, Huang XK. Effects of human β-defensin-3 on biofilm formation‑regulating genes dltB and icaA in Staphylococcus aureus. Mol Med Rep 2014; 10:825-31. [PMID: 24913184 DOI: 10.3892/mmr.2014.2309] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 04/08/2014] [Indexed: 11/06/2022] Open
Abstract
An understanding of the regulatory mechanisms that drive Staphylococcus aureus biofilm formation may lead to the development of an effective strategy to control the increasing number of refractory clinical infections it causes. The present study examined the effects of the antimicrobial agent human β‑defensin 3 (hBD‑3) and the antibiotics vancomycin and clindamycin on the expression of the S. aureus biofilm formation‑regulating genes, icaA and dltB, during bacterial adhesion and biofilm formation. Transcription (mRNA) levels of dlt and ica genes were measured using quantitative polymerase chain reaction, and slimes of S. aureus biofilm were examined with confocal scanning laser microscopy during S. aureus adhesion and biofilm formation. Although hBD‑3, vancomycin and clindamycin led to significantly attenuated biofilm formation, their treatment‑associated effects on the mRNA expression of dlt and ica were not identical. Vancomycin and clindamycin induced sustained expression of the dlt and ica genes, which may be harnessed to induce biofilm formation. However, hBD‑3 did not have a significant affect on the transcription level of dltB during either bacterial adhesion or biofilm formation. Therefore, the mechanism of hBD‑3 that regulated the suppression of biofilm formation appears to differ from the mechanisms of vancomycin and clindamycin.
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Affiliation(s)
- Qiang Huang
- Trauma Center of Daping Hospital, Third Military Medical University, Chongqing 404100, P.R. China
| | - Jun Fei
- Trauma Center of Daping Hospital, Third Military Medical University, Chongqing 404100, P.R. China
| | - Hong-Jun Yu
- Rehabilitation Department, Southwest Hospital, Third Military Medical University, Chongqing 404100, P.R. China
| | - Yuan-Bin Gou
- Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 404100, P.R. China
| | - Xian-Kai Huang
- Trauma Center of Daping Hospital, Third Military Medical University, Chongqing 404100, P.R. China
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17
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Reichmann NT, Piçarra Cassona C, Monteiro JM, Bottomley AL, Corrigan RM, Foster SJ, Pinho MG, Gründling A. Differential localization of LTA synthesis proteins and their interaction with the cell division machinery in Staphylococcus aureus. Mol Microbiol 2014; 92:273-86. [PMID: 24533796 PMCID: PMC4065355 DOI: 10.1111/mmi.12551] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/12/2014] [Indexed: 11/28/2022]
Abstract
Lipoteichoic acid (LTA) is an important cell wall component of Gram-positive bacteria. In Staphylococcus aureus it consists of a polyglycerolphosphate-chain that is retained within the membrane via a glycolipid. Using an immunofluorescence approach, we show here that the LTA polymer is not surface exposed in S. aureus, as it can only be detected after digestion of the peptidoglycan layer. S. aureus mutants lacking LTA are enlarged and show aberrant positioning of septa, suggesting a link between LTA synthesis and the cell division process. Using a bacterial two-hybrid approach, we show that the three key LTA synthesis proteins, YpfP and LtaA, involved in glycolipid production, and LtaS, required for LTA backbone synthesis, interact with one another. All three proteins also interacted with numerous cell division and peptidoglycan synthesis proteins, suggesting the formation of a multi-enzyme complex and providing further evidence for the co-ordination of these processes. When assessed by fluorescence microscopy, YpfP and LtaA fluorescent protein fusions localized to the membrane while the LtaS enzyme accumulated at the cell division site. These data support a model whereby LTA backbone synthesis proceeds in S. aureus at the division site in co-ordination with cell division, while glycolipid synthesis takes place throughout the membrane.
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Affiliation(s)
- Nathalie T Reichmann
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College LondonLondon, SW7 2AZ, UK
| | - Carolina Piçarra Cassona
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College LondonLondon, SW7 2AZ, UK
| | - João M Monteiro
- Instituto de Technologia Química e Biológica, Universidade Nova de LisboaOeiras, Portugal
| | - Amy L Bottomley
- The Krebs Institute, Department of Molecular Biology and Biotechnology, University of SheffieldSheffield, UK
| | - Rebecca M Corrigan
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College LondonLondon, SW7 2AZ, UK
| | - Simon J Foster
- The Krebs Institute, Department of Molecular Biology and Biotechnology, University of SheffieldSheffield, UK
| | - Mariana G Pinho
- Instituto de Technologia Química e Biológica, Universidade Nova de LisboaOeiras, Portugal
| | - Angelika Gründling
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College LondonLondon, SW7 2AZ, UK
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18
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Revilla-Guarinos A, Gebhard S, Mascher T, Zúñiga M. Defence against antimicrobial peptides: different strategies inFirmicutes. Environ Microbiol 2014; 16:1225-37. [DOI: 10.1111/1462-2920.12400] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 01/10/2014] [Accepted: 01/11/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Ainhoa Revilla-Guarinos
- Departamento de Biotecnología; Instituto de Agroquímica y Tecnología de Alimentos (IATA); Consejo Superior de Investigaciones Científicas (CSIC); Paterna Valencia Spain
| | - Susanne Gebhard
- Department Biologie I, Mikrobiologie; Ludwig-Maximilians-Universität München; Planegg-Martinsried Germany
| | - Thorsten Mascher
- Department Biologie I, Mikrobiologie; Ludwig-Maximilians-Universität München; Planegg-Martinsried Germany
| | - Manuel Zúñiga
- Departamento de Biotecnología; Instituto de Agroquímica y Tecnología de Alimentos (IATA); Consejo Superior de Investigaciones Científicas (CSIC); Paterna Valencia Spain
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19
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Lipoteichoic acids, phosphate-containing polymers in the envelope of gram-positive bacteria. J Bacteriol 2014; 196:1133-42. [PMID: 24415723 DOI: 10.1128/jb.01155-13] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Lipoteichoic acids (LTA) are polymers of alternating units of a polyhydroxy alkane, including glycerol and ribitol, and phosphoric acid, joined to form phosphodiester units that are found in the envelope of Gram-positive bacteria. Here we review four different types of LTA that can be distinguished on the basis of their chemical structure and describe recent advances in the biosynthesis pathway for type I LTA, d-alanylated polyglycerol-phosphate linked to di-glucosyl-diacylglycerol. The physiological functions of type I LTA are discussed in the context of inhibitors that block their synthesis and of mutants with discrete synthesis defects. Research on LTA structure and function represents a large frontier that has been investigated in only few Gram-positive bacteria.
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20
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D-alanine modification of a protease-susceptible outer membrane component by the Bordetella pertussis dra locus promotes resistance to antimicrobial peptides and polymorphonuclear leukocyte-mediated killing. J Bacteriol 2013; 195:5102-11. [PMID: 24013634 DOI: 10.1128/jb.00510-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bordetella pertussis is the causative agent of pertussis, a highly contagious disease of the human respiratory tract. Despite very high vaccine coverage, pertussis has reemerged as a serious threat in the United States and many developing countries. Thus, it is important to pursue research to discover unknown pathogenic mechanisms of B. pertussis. We have investigated a previously uncharacterized locus in B. pertussis, the dra locus, which is homologous to the dlt operons of Gram-positive bacteria. The absence of the dra locus resulted in increased sensitivity to the killing action of antimicrobial peptides (AMPs) and human phagocytes. Compared to the wild-type cells, the mutant cells bound higher levels of cationic proteins and peptides, suggesting that dra contributes to AMP resistance by decreasing the electronegativity of the cell surface. The presence of dra led to the incorporation of d-alanine into an outer membrane component that is susceptible to proteinase K cleavage. We conclude that dra encodes a virulence-associated determinant and contributes to the immune resistance of B. pertussis. With these findings, we have identified a new mechanism of surface modification in B. pertussis which may also be relevant in other Gram-negative pathogens.
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21
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Reichmann NT, Cassona CP, Gründling A. Revised mechanism of D-alanine incorporation into cell wall polymers in Gram-positive bacteria. MICROBIOLOGY-SGM 2013; 159:1868-1877. [PMID: 23858088 PMCID: PMC3783018 DOI: 10.1099/mic.0.069898-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Teichoic acids (TAs) are important for growth, biofilm formation, adhesion and virulence of Gram-positive bacterial pathogens. The chemical structures of the TAs vary between bacteria, though they typically consist of zwitterionic polymers that are anchored to either the peptidoglycan layer as in the case of wall teichoic acid (WTA) or the cell membrane and named lipoteichoic acid (LTA). The polymers are modified with D-alanines and a lack of this decoration leads to increased susceptibility to cationic antimicrobial peptides. Four proteins, DltA-D, are essential for the incorporation of d-alanines into cell wall polymers and it has been established that DltA transfers D-alanines in the cytoplasm of the cell onto the carrier protein DltC. However, two conflicting models have been proposed for the remainder of the mechanism. Using a cellular protein localization and membrane topology analysis, we show here that DltC does not traverse the membrane and that DltD is anchored to the outside of the cell. These data are in agreement with the originally proposed model for D-alanine incorporation through a process that has been proposed to proceed via a D-alanine undecaprenyl phosphate membrane intermediate. Furthermore, we found that WTA isolated from a Staphylococcus aureus strain lacking LTA contains only a small amount of D-alanine, indicating that LTA has a role, either direct or indirect, in the efficient D-alanine incorporation into WTA in living cells.
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Affiliation(s)
- Nathalie T Reichmann
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Carolina Picarra Cassona
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Angelika Gründling
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
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22
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Characterization of a regulatory network of peptide antibiotic detoxification modules in Lactobacillus casei BL23. Appl Environ Microbiol 2013; 79:3160-70. [PMID: 23455349 DOI: 10.1128/aem.00178-13] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two-component systems (TCS) are major signal transduction pathways that allow bacteria to detect and respond to environmental and intracellular changes. A group of TCS has been shown to be involved in the response against antimicrobial peptides (AMPs). These TCS are characterized by the possession of intramembrane-sensing histidine kinases, and they are usually associated with ABC transporters of the peptide-7 exporter family (Pep7E). Lactobacillus casei BL23 encodes two TCS belonging to this group (TCS09 and TCS12) that are located next to two ABC transporters (ABC09 and ABC12), as well as a third Pep7E ABC transporter not genetically associated with any TCS (orphan ABC). This study addressed the involvement of modules TCS09/ABC09 and TCS12/ABC12 in AMP resistance. Results showed that both systems contribute to L. casei resistance to AMPs, and that each TCS constitutes a functional unit with its corresponding ABC transporter. Analysis of transcriptional levels showed that module 09 is required for the induction of ABC09 expression in response to nisin. In contrast, module 12 controls a wider regulon that encompasses the orphan ABC, the dlt operon (d-alanylation of teichoid acids), and the mprF gene (l-lysinylation of phospholipids), thereby controlling properties of the cell envelope. Furthermore, the characterization of a dltA mutant showed that Dlt plays a major role in AMP resistance in L. casei. This is the first report on the regulation of the response of L. casei to AMPs, giving insight into its ability to adapt to the challenging environments that it encounters as a probiotic microorganism.
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23
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The quest for probiotic effector molecules—Unraveling strain specificity at the molecular level. Pharmacol Res 2013; 69:61-74. [DOI: 10.1016/j.phrs.2012.09.010] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 09/26/2012] [Accepted: 09/27/2012] [Indexed: 12/25/2022]
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24
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Lee JY, Pajarillo EAB, Kim MJ, Chae JP, Kang DK. Proteomic and Transcriptional Analysis of Lactobacillus johnsonii PF01 during Bile Salt Exposure by iTRAQ Shotgun Proteomics and Quantitative RT-PCR. J Proteome Res 2012. [DOI: 10.1021/pr300794y] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Ji Yoon Lee
- National
Instrumentation Center
for Environmental Management, Seoul National University, Seoul 151-921, Republic of Korea
| | | | - Min Jeong Kim
- Department of Animal Resources
Science, Dankook University, Cheonan 330-714,
Republic of Korea
| | - Jong Pyo Chae
- Department of Animal Resources
Science, Dankook University, Cheonan 330-714,
Republic of Korea
| | - Dae-Kyung Kang
- Department of Animal Resources
Science, Dankook University, Cheonan 330-714,
Republic of Korea
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25
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Balibar CJ, Shen X, McGuire D, Yu D, McKenney D, Tao J. cwrA, a gene that specifically responds to cell wall damage in Staphylococcus aureus. MICROBIOLOGY-SGM 2010; 156:1372-1383. [PMID: 20167623 DOI: 10.1099/mic.0.036129-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Transcriptional profiling data accumulated in recent years for the clinically relevant pathogen Staphylococcus aureus have established a cell wall stress stimulon, which comprises a coordinately regulated set of genes that are upregulated in response to blockage of cell wall biogenesis. In particular, the expression of cwrA (SA2343, N315 notation), which encodes a putative 63 amino acid polypeptide of unknown biological function, increases over 100-fold in response to cell wall inhibition. Herein, we seek to understand the biological role that this gene plays in S. aureus. cwrA was found to be robustly induced by all cell wall-targeting antibiotics tested - vancomycin, oxacillin, penicillin G, phosphomycin, imipenem, hymeglusin and bacitracin - but not by antibiotics with other mechanisms of action, including ciprofloxacin, erythromycin, chloramphenicol, triclosan, rifampicin, novobiocin and carbonyl cyanide 3-chlorophenylhydrazone. Although a DeltacwrA S. aureus strain had no appreciable shift in MICs for cell wall-targeting antibiotics, the knockout was shown to have reduced cell wall integrity in a variety of other assays. Additionally, the gene was shown to be important for virulence in a mouse sepsis model of infection.
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Affiliation(s)
- Carl J Balibar
- Department of Infectious Diseases, Novartis Institutes for BioMedical Research, 500 Technology Square, Cambridge, MA 02139, USA
| | - Xiaoyu Shen
- Department of Infectious Diseases, Novartis Institutes for BioMedical Research, 500 Technology Square, Cambridge, MA 02139, USA
| | - Dorothy McGuire
- Department of Infectious Diseases, Novartis Institutes for BioMedical Research, 500 Technology Square, Cambridge, MA 02139, USA
| | - Donghui Yu
- Department of Infectious Diseases, Novartis Institutes for BioMedical Research, 500 Technology Square, Cambridge, MA 02139, USA
| | - David McKenney
- Department of Infectious Diseases, Novartis Institutes for BioMedical Research, 500 Technology Square, Cambridge, MA 02139, USA
| | - Jianshi Tao
- Department of Infectious Diseases, Novartis Institutes for BioMedical Research, 500 Technology Square, Cambridge, MA 02139, USA
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26
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Xia G, Kohler T, Peschel A. The wall teichoic acid and lipoteichoic acid polymers of Staphylococcus aureus. Int J Med Microbiol 2009; 300:148-54. [PMID: 19896895 DOI: 10.1016/j.ijmm.2009.10.001] [Citation(s) in RCA: 168] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Staphylococci and most other Gram-positive bacteria incorporate complex teichoic acid (TA) polymers into their cell envelopes. Several crucial roles in Staphylococcus aureus fitness and cell wall maintenance have been assigned to these polymers, which are either covalently linked to peptidoglycan (wall teichoic acid, WTA) or to the cytoplasmic membrane (lipoteichoic acid, LTA). However, the exact TA structures, functions, and biosynthetic pathways are only superficially understood. Recently, most of the enzymes mediating TA biosynthesis have been identified and mutants lacking or with defined changes in WTA or LTA have become available. Their characterization has revealed crucial roles of TAs in protection against harmful molecules and environmental stresses; in control of enzymes directing cell division or morphogenesis and of cation homeostasis; and in interaction with host or bacteriophage receptors and biomaterials. Accordingly, several in vivo studies have demonstrated the importance of WTA and LTA in S. aureus colonization, infection, and immune evasion. TAs and enzymes required for TA biosynthesis represent attractive candidates for novel vaccines and antibiotics and are targeted by recently developed antibacterial therapeutics.
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Affiliation(s)
- Guoqing Xia
- Division of Cellular and Molecular Microbiology, Institute of Medical Microbiology and Hygiene, University of Tübingen, Elfriede-Aulhorn-Strasse 6, D-72076 Tübingen, Germany
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The dlt operon of Bacillus cereus is required for resistance to cationic antimicrobial peptides and for virulence in insects. J Bacteriol 2009; 191:7063-73. [PMID: 19767427 DOI: 10.1128/jb.00892-09] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The dlt operon encodes proteins that alanylate teichoic acids, the major components of cell walls of gram-positive bacteria. This generates a net positive charge on bacterial cell walls, repulsing positively charged molecules and conferring resistance to animal and human cationic antimicrobial peptides (AMPs) in gram-positive pathogenic bacteria. AMPs damage the bacterial membrane and are the most effective components of the humoral immune response against bacteria. We investigated the role of the dlt operon in insect virulence by inactivating this operon in Bacillus cereus, which is both an opportunistic human pathogen and an insect pathogen. The Delta dlt(Bc) mutant displayed several morphological alterations but grew at a rate similar to that for the wild-type strain. This mutant was less resistant to protamine and several bacterial cationic AMPs, such as nisin, polymyxin B, and colistin, in vitro. It was also less resistant to molecules from the insect humoral immune system, lysozyme, and cationic AMP cecropin B from Spodoptera frugiperda. Delta dlt(Bc) was as pathogenic as the wild-type strain in oral infections of Galleria mellonella but much less virulent when injected into the hemocoels of G. mellonella and Spodoptera littoralis. We detected the dlt operon in three gram-negative genera: Erwinia (Erwinia carotovora), Bordetella (Bordetella pertussis, Bordetella parapertussis, and Bordetella bronchiseptica), and Photorhabdus (the entomopathogenic bacterium Photorhabdus luminescens TT01, the dlt operon of which did not restore cationic AMP resistance in Delta dlt(Bc)). We suggest that the dlt operon protects B. cereus against insect humoral immune mediators, including hemolymph cationic AMPs, and may be critical for the establishment of lethal septicemia in insects and in nosocomial infections in humans.
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Teichoic acids and related cell-wall glycopolymers in Gram-positive physiology and host interactions. Nat Rev Microbiol 2008; 6:276-87. [PMID: 18327271 DOI: 10.1038/nrmicro1861] [Citation(s) in RCA: 539] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Most Gram-positive bacteria incorporate membrane- or peptidoglycan-attached carbohydrate-based polymers into their cell envelopes. Such cell-wall glycopolymers (CWGs) often have highly variable structures and have crucial roles in protecting, connecting and controlling the major envelope constituents. Further important roles of CWGs in host-cell adhesion, inflammation and immune activation have also been described in recent years. Identifying and harnessing highly conserved or species-specific structural features of CWGs offers excellent opportunities for developing new antibiotics, vaccines and diagnostics for use in the fight against severe infectious diseases, such as sepsis, pneumonia, anthrax and tuberculosis.
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Gründling A, Schneewind O. Genes required for glycolipid synthesis and lipoteichoic acid anchoring in Staphylococcus aureus. J Bacteriol 2007; 189:2521-30. [PMID: 17209021 PMCID: PMC1899383 DOI: 10.1128/jb.01683-06] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Staphylococcus aureus lipoteichoic acid (LTA) is composed of a linear 1,3-linked polyglycerolphosphate chain and is tethered to the bacterial membrane by a glycolipid (diglucosyl-diacylglycerol [Glc2-DAG]). Glc2-DAG is synthesized in the bacterial cytoplasm by YpfP, a processive enzyme that transfers glucose to diacylglycerol (DAG), using UDP-glucose as its substrate. Here we present evidence that the S. aureus alpha-phosphoglucomutase (PgcA) and UTP:alpha-glucose 1-phosphate uridyltransferase (GtaB) homologs are required for the synthesis of Glc2-DAG. LtaA (lipoteichoic acid protein A), a predicted membrane permease whose structural gene is located in an operon with ypfP, is not involved in Glc2-DAG synthesis but is required for synthesis of glycolipid-anchored LTA. Our data suggest a model in which LtaA facilitates the transport of Glc2-DAG from the inner (cytoplasmic) leaflet to the outer leaflet of the plasma membrane, delivering Glc2-DAG as a substrate for LTA synthesis, thereby generating glycolipid-anchored LTA. Glycolipid anchoring of LTA appears to play an important role during infection, as S. aureus variants lacking ltaA display defects in the pathogenesis of animal infections.
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Affiliation(s)
- Angelika Gründling
- Department of Microbiology, 920 East 58th Street, Chicago, IL 60637, USA
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Kovács M, Halfmann A, Fedtke I, Heintz M, Peschel A, Vollmer W, Hakenbeck R, Brückner R. A functional dlt operon, encoding proteins required for incorporation of d-alanine in teichoic acids in gram-positive bacteria, confers resistance to cationic antimicrobial peptides in Streptococcus pneumoniae. J Bacteriol 2006; 188:5797-805. [PMID: 16885447 PMCID: PMC1540085 DOI: 10.1128/jb.00336-06] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Accepted: 05/26/2006] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pneumoniae is one of the few species within the group of low-G +C gram-positive bacteria reported to contain no d-alanine in teichoic acids, although the dltABCD operon encoding proteins responsible for d-alanylation is present in the genomes of two S. pneumoniae strains, the laboratory strain R6 and the clinical isolate TIGR4. The annotation of dltA in R6 predicts a protein, d-alanine-d-alanyl carrier protein ligase (Dcl), that is shorter at the amino terminus than all other Dcl proteins. Translation of dltA could also start upstream of the annotated TTG start codon at a GTG, resulting in the premature termination of dltA translation at a stop codon. Applying a novel integrative translation probe plasmid with Escherichia coli 'lacZ as a reporter, we could demonstrate that dltA translation starts at the upstream GTG. Consequently, S. pneumoniae R6 is a dltA mutant, whereas S. pneumoniae D39, the parental strain of R6, and Rx, another derivative of D39, contained intact dltA genes. Repair of the stop codon in dltA of R6 and insertional inactivation of dltA in D39 and Rx yielded pairs of dltA-deficient and dltA-proficient strains. Subsequent phenotypic analysis showed that dltA inactivation resulted in enhanced sensitivity to the cationic antimicrobial peptides nisin and gallidermin, a phenotype fully consistent with those of dltA mutants of other gram-positive bacteria. In addition, mild alkaline hydrolysis of heat-inactivated whole cells released d-alanine from dltA-proficient strains, but not from dltA mutants. The results of our study suggest that, as in many other low-G+C gram-positive bacteria, teichoic acids of S. pneumoniae contain d-alanine residues in order to protect this human pathogen against the actions of cationic antimicrobial peptides.
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Affiliation(s)
- Márta Kovács
- University of Kaiserslautern, Department of Microbiology, Paul Ehrlich Strasse 23, D-67663 Kaiserslautern, Germany
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Palumbo E, Deghorain M, Cocconcelli PS, Kleerebezem M, Geyer A, Hartung T, Morath S, Hols P. D-alanyl ester depletion of teichoic acids in Lactobacillus plantarum results in a major modification of lipoteichoic acid composition and cell wall perforations at the septum mediated by the Acm2 autolysin. J Bacteriol 2006; 188:3709-15. [PMID: 16672624 PMCID: PMC1482858 DOI: 10.1128/jb.188.10.3709-3715.2006] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Accepted: 02/27/2006] [Indexed: 11/20/2022] Open
Abstract
The insertional inactivation of the dlt operon from Lactobacillus plantarum NCIMB8826 had a strong impact on lipoteichoic acid (LTA) composition, resulting in a major reduction in D-alanyl ester content. Unexpectedly, mutant LTA showed high levels of glucosylation and were threefold longer than wild-type LTA. The dlt mutation resulted in a reduced growth rate and increased cell lysis during the exponential and stationary growth phases. Microscopy analysis revealed increased cell length, damaged dividing cells, and perforations of the envelope in the septal region. The observed defects in the separation process, cell envelope perforation, and autolysis of the dlt mutant could be partially attributed to the L. plantarum Acm2 peptidoglycan hydrolase.
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Affiliation(s)
- Emmanuelle Palumbo
- Unité de Génétique, Institut des Sciences de la Vie, Université catholique de Louvain, Louvain-La-Neuve, Belgium.
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Grangette C, Nutten S, Palumbo E, Morath S, Hermann C, Dewulf J, Pot B, Hartung T, Hols P, Mercenier A. Enhanced antiinflammatory capacity of a Lactobacillus plantarum mutant synthesizing modified teichoic acids. Proc Natl Acad Sci U S A 2005; 102:10321-6. [PMID: 15985548 PMCID: PMC1177390 DOI: 10.1073/pnas.0504084102] [Citation(s) in RCA: 325] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Teichoic acids (TAs), and especially lipoteichoic acids (LTAs), are one of the main immunostimulatory components of pathogenic Gram-positive bacteria. Their contribution to the immunomodulatory properties of commensal bacteria and especially of lactic acid bacteria has not yet been investigated in detail. To evaluate the role of TAs in the interaction between lactic acid bacteria and the immune system, we analyzed the antiinflammatory properties of a mutant of Lactobacillus plantarum NCIMB8826 affected in the TA biosynthesis pathway both in vitro (mononuclear cells stimulation) and in vivo (murine model of colitis). This Dlt- mutant was found to incorporate much less D-Ala in its TAs than the WT strain. This defect significantly impacted the immunomodulation reactions induced by the bacterium, as shown by a dramatically reduced secretion of proinflammatory cytokines by peripheral blood mononuclear cells and monocytes stimulated by the Dlt- mutant as compared with the parental strain. Concomitantly, a significant increase in IL-10 production was stimulated by the Dlt- mutant in comparison with the WT strain. Moreover, the proinflammatory capacity of L. plantarum-purified LTA was found to be Toll-like receptor 2-dependent. Consistent with the in vitro results, the Dlt- mutant was significantly more protective in a murine colitis model than its WT counterpart. The results indicated that composition of LTA within the whole-cell context of L. plantarum can modulate proinflammatory or antiinflammatory immune responses.
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Affiliation(s)
- Corinne Grangette
- Laboratoire de Bactériologie des Ecosytèmes, Institut Pasteur de Lille-Institut de Biologie de Lille, 59019 Lille Cedex, France.
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May JJ, Finking R, Wiegeshoff F, Weber TT, Bandur N, Koert U, Marahiel MA. Inhibition of the D-alanine:D-alanyl carrier protein ligase from Bacillus subtilis increases the bacterium's susceptibility to antibiotics that target the cell wall. FEBS J 2005; 272:2993-3003. [PMID: 15955059 DOI: 10.1111/j.1742-4658.2005.04700.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The surface charge as well as the electrochemical properties and ligand binding abilities of the Gram-positive cell wall is controlled by the D-alanylation of the lipoteichoic acid. The incorporation of D-Ala into lipoteichoic acid requires the D-alanine:D-alanyl carrier protein ligase (DltA) and the carrier protein (DltC). We have heterologously expressed, purified, and assayed the substrate selectivity of the recombinant proteins DltA with its substrate DltC. We found that apo-DltC is recognized by both endogenous 4'-phosphopantetheinyl transferases AcpS and Sfp. After the biochemical characterization of DltA and DltC, we designed an inhibitor (D-alanylacyl-sulfamoyl-adenosine), which is able to block the D-Ala adenylation by DltA at a K(i) value of 232 nM vitro. We also performed in vivo studies and determined a significant inhibition of growth for different Bacillus subtilis strains when the inhibitor is used in combination with vancomycin.
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Affiliation(s)
- Juergen J May
- Philipps-Universität Marburg, Fachbereich Chemie/Biochemie, Marburg, Germany
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Steen A, Palumbo E, Deghorain M, Cocconcelli PS, Delcour J, Kuipers OP, Kok J, Buist G, Hols P. Autolysis of Lactococcus lactis is increased upon D-alanine depletion of peptidoglycan and lipoteichoic acids. J Bacteriol 2005; 187:114-24. [PMID: 15601695 PMCID: PMC538808 DOI: 10.1128/jb.187.1.114-124.2005] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mutations in the genes encoding enzymes responsible for the incorporation of D-Ala into the cell wall of Lactococcus lactis affect autolysis. An L. lactis alanine racemase (alr) mutant is strictly dependent on an external supply of D-Ala to be able to synthesize peptidoglycan and to incorporate D-Ala in the lipoteichoic acids (LTA). The mutant lyses rapidly when D-Ala is removed at mid-exponential growth. AcmA, the major lactococcal autolysin, is partially involved in the increased lysis since an alr acmA double mutant still lyses, albeit to a lesser extent. To investigate the role of D-Ala on LTA in the increased cell lysis, a dltD mutant of L. lactis was investigated, since this mutant is only affected in the D-alanylation of LTA and not the synthesis of peptidoglycan. Mutation of dltD results in increased lysis, showing that D-alanylation of LTA also influences autolysis. Since a dltD acmA double mutant does not lyse, the lysis of the dltD mutant is totally AcmA dependent. Zymographic analysis shows that no degradation of AcmA takes place in the dltD mutant, whereas AcmA is degraded by the extracellular protease HtrA in the wild-type strain. In L. lactis, LTA has been shown to be involved in controlled (directed) binding of AcmA. LTA lacking D-Ala has been reported in other bacterial species to have an improved capacity for autolysin binding. Mutation of dltD in L. lactis, however, does not affect peptidoglycan binding of AcmA; neither the amount of AcmA binding to the cells nor the binding to specific loci is altered. In conclusion, D-Ala depletion of the cell wall causes lysis by two distinct mechanisms. First, it results in an altered peptidoglycan that is more susceptible to lysis by AcmA and also by other factors, e.g., one or more of the other (putative) cell wall hydrolases expressed by L. lactis. Second, reduced amounts of D-Ala on LTA result in decreased degradation of AcmA by HtrA, which results in increased lytic activity.
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Affiliation(s)
- Anton Steen
- Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
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Nouaille S, Commissaire J, Gratadoux JJ, Ravn P, Bolotin A, Gruss A, Le Loir Y, Langella P. Influence of lipoteichoic acid D-alanylation on protein secretion in Lactococcus lactis as revealed by random mutagenesis. Appl Environ Microbiol 2004; 70:1600-7. [PMID: 15006784 PMCID: PMC368283 DOI: 10.1128/aem.70.3.1600-1607.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lactococcus lactis, a food-grade nonpathogenic lactic acid bacterium, is a good candidate for the production of heterologous proteins of therapeutic interest. We examined host factors that affect secretion of heterologous proteins in L. lactis. Random insertional mutagenesis was performed with L. lactis strain MG1363 carrying a staphylococcal nuclease (Nuc) reporter cassette in its chromosome. This cassette encodes a fusion protein between the signal peptide of the Usp45 lactococcal protein and the mature moiety of a truncated form of Nuc (NucT). The Nuc secretion efficiency (secreted NucT versus total NucT) from this construct is low in L. lactis (approximately 40%). Twenty mutants affected in NucT production and/or in secretion capacity were selected and identified. In these mutants, several independent insertions mapped in the dltA gene (involved in D-alanine transfer in lipoteichoic acids) and resulted in a NucT secretion defect. Characterization of the dltA mutant phenotype with respect to NucT secretion revealed that it is involved in a late secretion stage by causing mature NucT entrapment at the cell surface.
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Affiliation(s)
- S Nouaille
- Unité de Recherches Laitières et de Génétique Appliquée, Institut National de la Recherche Agronomique, Domaine de Vilvert, 78352 Jouy en Josas cedex, France
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Neuhaus FC, Baddiley J. A continuum of anionic charge: structures and functions of D-alanyl-teichoic acids in gram-positive bacteria. Microbiol Mol Biol Rev 2003; 67:686-723. [PMID: 14665680 PMCID: PMC309049 DOI: 10.1128/mmbr.67.4.686-723.2003] [Citation(s) in RCA: 723] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Teichoic acids (TAs) are major wall and membrane components of most gram-positive bacteria. With few exceptions, they are polymers of glycerol-phosphate or ribitol-phosphate to which are attached glycosyl and D-alanyl ester residues. Wall TA is attached to peptidoglycan via a linkage unit, whereas lipoteichoic acid is attached to glycolipid intercalated in the membrane. Together with peptidoglycan, these polymers make up a polyanionic matrix that functions in (i) cation homeostasis; (ii) trafficking of ions, nutrients, proteins, and antibiotics; (iii) regulation of autolysins; and (iv) presentation of envelope proteins. The esterification of TAs with D-alanyl esters provides a means of modulating the net anionic charge, determining the cationic binding capacity, and displaying cations in the wall. This review addresses the structures and functions of D-alanyl-TAs, the D-alanylation system encoded by the dlt operon, and the roles of TAs in cell growth. The importance of dlt in the physiology of many organisms is illustrated by the variety of mutant phenotypes. In addition, advances in our understanding of D-alanyl ester function in virulence and host-mediated responses have been made possible through targeted mutagenesis of dlt. Studies of the mechanism of D-alanylation have identified two potential targets of antibacterial action and provided possible screening reactions for designing novel agents targeted to D-alanyl-TA synthesis.
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Affiliation(s)
- Francis C Neuhaus
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208. USA.
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Poyart C, Pellegrini E, Marceau M, Baptista M, Jaubert F, Lamy MC, Trieu-Cuot P. Attenuated virulence of Streptococcus agalactiae deficient in D-alanyl-lipoteichoic acid is due to an increased susceptibility to defensins and phagocytic cells. Mol Microbiol 2003; 49:1615-25. [PMID: 12950925 DOI: 10.1046/j.1365-2958.2003.03655.x] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
D-alanylation of lipoteichoic acid (LTA), allows Gram-positive bacteria to modulate their surface charge, regulate ligand binding and control the electromechanical properties of the cell wall. In this study, the role of D-alanyl LTA in the virulence of the extracellular pathogen Streptococcus agalactiae was investigated. We demonstrate that a DltA- isogenic mutant displays an increased susceptibility to host defence peptides such as human defensins and animal-derived cationic peptides. Accordingly, the mutant strain is more susceptible to killing by mice bone marrow-derived macrophages and human neutrophils than the wild-type strain. In addition, the virulence of the DltA- mutant is severely impaired in mouse and neonatal rat models. This mutant was eliminated more rapidly than the wild-type strain from the lung of three-week-old mice inoculated intranasally and, consequently, is unable to induce a pneumonia. Finally, after intravenous injection of three-week-old mice, the survival of the DltA- mutant is markedly reduced in the blood in comparison to that of the wild-type strain. We hypothesize that the decreased virulence of the DltA- mutant is a consequence of its increased susceptibility to cationic antimicrobial peptides and to killing by phagocytes. These results demonstrate that the D-alanylation of LTA contributes to the virulence of S. agalactiae.
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Affiliation(s)
- Claire Poyart
- Laboratoire Mixte Pasteur-Necker de Recherche sur les Streptocoques et Streptococcies, Faculté de Médecine Necker-Enfants Malades, 75730 Paris Cedex 15, France.
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Abachin E, Poyart C, Pellegrini E, Milohanic E, Fiedler F, Berche P, Trieu-Cuot P. Formation of D-alanyl-lipoteichoic acid is required for adhesion and virulence of Listeria monocytogenes. Mol Microbiol 2002; 43:1-14. [PMID: 11849532 DOI: 10.1046/j.1365-2958.2002.02723.x] [Citation(s) in RCA: 202] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The dlt operon of Gram-positive bacteria comprises four genes (dltA, dltB, dltC and dltD) that catalyse the incorporation of D-alanine residues into the cell wall-associated lipoteichoic acids (LTAs). In this work, we characterized the dlt operon of Listeria monocytogenes and constructed a D-Ala-deficient LTA mutant by inactivating the first gene (dltA) of this operon. The DltA- mutant did not show any morphological alterations and its growth rate was similar to that of the wild-type strain. However, it exhibited an increased susceptibility to the cationic peptides colistin, nisin and polymyxin B. The virulence of the DltA- mutant was severely impaired in a mouse infection model (4 log increase in the LD50) and, in vitro, the adherence of the mutant to various cell lines (murine bone marrow-derived macrophages and hepatocytes and a human epithelial cell line) was strongly restricted, although the amounts of surface proteins implicated in virulence (ActA, InlA and InlB) remains unaffected. We suggest that the decreased adherence of the DltA- mutant to non-phagocytic and phagocytic cells might be as a result of the increased electronegativity of its charge surface and/or the presence at the bacterial surface of adhesins possessing altered binding activities. These results show that the D-alanylation of the LTAs contributes to the virulence of the intracellular pathogen L. monocytogenes.
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Affiliation(s)
- Eric Abachin
- Laboratoire de Microbiologie, INSERM U-411, Paris, France
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Poyart C, Lamy MC, Boumaila C, Fiedler F, Trieu-Cuot P. Regulation of D-alanyl-lipoteichoic acid biosynthesis in Streptococcus agalactiae involves a novel two-component regulatory system. J Bacteriol 2001; 183:6324-34. [PMID: 11591677 PMCID: PMC100127 DOI: 10.1128/jb.183.21.6324-6334.2001] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The dlt operon of gram-positive bacteria comprises four genes (dltA, dltB, dltC, and dltD) that catalyze the incorporation of D-alanine residues into the lipoteichoic acids (LTAs). In this work, we characterized the dlt operon of Streptococcus agalactiae, which, in addition to the dltA to dltD genes, included two regulatory genes, designated dltR and dltS, located upstream of dltA. The dltR gene encodes a 224-amino-acid putative response regulator belonging to the OmpR family of regulatory proteins. The dltS gene codes for a 395-amino-acid putative histidine kinase thought to be involved in the sensing of environmental signals. The dlt operon of S. agalactiae is mainly transcribed from the P(dltR) promoter, which directs synthesis of a 6.5-kb transcript encompassing dltR, dltS, dltA, dltB, dltC, and dltD, and from a weaker promoter, P(dltA), which is located in the 3' extremity of dltS. We demonstrate that P(dltR), but not P(dlA), is activated by DltR in the presence of DltS in D-Ala-deficient LTA mutants resulting from insertional inactivation of the dltA gene, which encodes the cytoplasmic D-alanine-D-alanyl carrier ligase DltA. Expression of the dlt operon does not require DltR and DltS, since the basal activity of P(dltR) is high, being 20-fold that of the constitutive promoter P(aphA-3) which directs synthesis of the kanamycin resistance gene aphA-3 in various gram-positive bacteria. We hypothesize that the role of DltR and DltS in the control of expression of the dlt operon is to maintain the level of D-Ala esters in LTAs at a constant and appropriate value whatever the environmental conditions. The DltA(-) mutant displayed the ability to form clumps in standing culture and exhibited an increased susceptibility to the cationic antimicrobial polypeptide colistin.
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Affiliation(s)
- C Poyart
- Laboratoire de Microbiologie, INSERM U-411, Faculté de Médecine Necker-Enfants Malades, 75730 Paris Cedex 15, France
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Volkman BF, Zhang Q, Debabov DV, Rivera E, Kresheck GC, Neuhaus FC. Biosynthesis of d-Alanyl-Lipoteichoic Acid: The Tertiary Structure of apo-d-Alanyl Carrier Protein,. Biochemistry 2001. [DOI: 10.1021/bi010355a] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Brian F. Volkman
- Department of Biochemistry and National Magnetic Resonance Facility at Madison, University of WisconsinMadison, Madison, Wisconsin 53706-1544, Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2153 Sheridan Road, Evanston, Illinois 60208-3500, and Department of Chemistry, Northern Illinois University, DeKalb, Illinois 60115
| | - Qunying Zhang
- Department of Biochemistry and National Magnetic Resonance Facility at Madison, University of WisconsinMadison, Madison, Wisconsin 53706-1544, Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2153 Sheridan Road, Evanston, Illinois 60208-3500, and Department of Chemistry, Northern Illinois University, DeKalb, Illinois 60115
| | - Dmitri V. Debabov
- Department of Biochemistry and National Magnetic Resonance Facility at Madison, University of WisconsinMadison, Madison, Wisconsin 53706-1544, Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2153 Sheridan Road, Evanston, Illinois 60208-3500, and Department of Chemistry, Northern Illinois University, DeKalb, Illinois 60115
| | - Edwin Rivera
- Department of Biochemistry and National Magnetic Resonance Facility at Madison, University of WisconsinMadison, Madison, Wisconsin 53706-1544, Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2153 Sheridan Road, Evanston, Illinois 60208-3500, and Department of Chemistry, Northern Illinois University, DeKalb, Illinois 60115
| | - Gordon C. Kresheck
- Department of Biochemistry and National Magnetic Resonance Facility at Madison, University of WisconsinMadison, Madison, Wisconsin 53706-1544, Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2153 Sheridan Road, Evanston, Illinois 60208-3500, and Department of Chemistry, Northern Illinois University, DeKalb, Illinois 60115
| | - Francis C. Neuhaus
- Department of Biochemistry and National Magnetic Resonance Facility at Madison, University of WisconsinMadison, Madison, Wisconsin 53706-1544, Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2153 Sheridan Road, Evanston, Illinois 60208-3500, and Department of Chemistry, Northern Illinois University, DeKalb, Illinois 60115
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Kiriukhin MY, Debabov DV, Shinabarger DL, Neuhaus FC. Biosynthesis of the glycolipid anchor in lipoteichoic acid of Staphylococcus aureus RN4220: role of YpfP, the diglucosyldiacylglycerol synthase. J Bacteriol 2001; 183:3506-14. [PMID: 11344159 PMCID: PMC99649 DOI: 10.1128/jb.183.11.3506-3514.2001] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Staphylococcus aureus RN4220, lipoteichoic acid (LTA) is anchored in the membrane by a diglucosyldiacylglycerol moiety. The gene (ypfP) which encodes diglucosyldiacylglycerol synthase was recently cloned from Bacillus subtilis and expressed in Escherichia coli (P. Jorasch, F. P. Wolter, U. Zahringer, and E. Heinz, Mol. Microbiol. 29:419-430, 1998). To define the role of ypfP in this strain of S. aureus, a fragment of ypfP truncated from both ends was cloned into the thermosensitive replicon pVE6007 and used to inactivate ypfP. Chloramphenicol-resistant (ypfP::cat) clones did not synthesize the glycolipids monoglucosyldiacylglycerol and diglucosyldiacylglycerol. Thus, YpfP would appear to be the only diglucosyldiacylglycerol synthase in S. aureus providing glycolipid for LTA assembly. In LTA from the mutant, the glycolipid anchor is replaced by diacylglycerol. Although the doubling time of the mutant was identical to that of the wild type in Luria-Bertani (LB) medium, growth of the mutant in LB medium containing 1% glycine was not observed. This inhibition was antagonized by either L- or D-alanine. Moreover, viability of the mutant at 37 degrees C in 0.05 M phosphate (pH 7.2)-saline for 12 h was reduced to <0.1%. Addition of 0.1% D-glucose to the phosphate-saline ensured viability under these conditions. The autolysis of the ypfP::cat mutant in the presence of 0.05% Triton X-100 was 1.8-fold faster than that of the parental strain. Electron microscopy of the mutant revealed not only a small increase in cell size but also the presence of pleomorphic cells. Each of these phenotypes may be correlated with either (or both) a deficiency of free glycolipid in the membrane or the replacement of the usual glycolipid anchor of LTA with diacylglycerol.
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Affiliation(s)
- M Y Kiriukhin
- Department of Biochemistry, Molecular and Cell Biology, Northwestern University, 2153 Sheridan Road, Evanston, IL 60208, USA
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Kiriukhin MY, Neuhaus FC. D-alanylation of lipoteichoic acid: role of the D-alanyl carrier protein in acylation. J Bacteriol 2001; 183:2051-8. [PMID: 11222605 PMCID: PMC95102 DOI: 10.1128/jb.183.6.2051-2058.2001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The D-alanylation of membrane-associated lipoteichoic acid (LTA) in gram-positive organisms requires the D-alanine-D-alanyl carrier protein ligase (AMP) (Dcl) and the D-alanyl carrier protein (Dcp). The dlt operon encoding these proteins (dltA and dltC) also includes dltB and dltD. dltB encodes a putative transport system, while dltD encodes a protein which facilitates the binding of Dcp and Dcl for ligation with D-alanine and has thioesterase activity for mischarged D-alanyl-acyl carrier proteins (ACPs). In previous results it was shown that D-alanyl-Dcp donates its ester residue to membrane-associated LTA (M. P. Heaton and F. C. Neuhaus, J. Bacteriol. 176: 681-690, 1994). However, all efforts to identify an enzyme which catalyzes this D-alanylation process were unsuccessful. It was discovered that incubation of D-alanyl-Dcp in the presence of LTA resulted in the time-dependent hydrolysis of this D-alanyl thioester. D-Alanyl-ACP in the presence of LTA was not hydrolyzed. When Dcp was incubated with membrane-associated D-alanyl LTA, a time and concentration-dependent formation of D-alanyl-Dcp was found. The addition of NaCl to this reaction inhibited the formation of D-alanyl-Dcp and stimulated the hydrolysis of D-alanyl-Dcp. Since these reactions are specific for the carrier protein (Dcp), it is suggested that Dcp has a unique binding site which interacts with the poly(Gro-P) moiety of LTA. It is this specific interaction that provides the functional specificity for the D-alanylation process. The reversibility of this process provides a mechanism for the transacylation of the D-alanyl ester residues between LTA and wall teichoic acid.
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Affiliation(s)
- M Y Kiriukhin
- Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, Evanston, Illinois 60208-3500, USA
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Boyd DA, Cvitkovitch DG, Bleiweis AS, Kiriukhin MY, Debabov DV, Neuhaus FC, Hamilton IR. Defects in D-alanyl-lipoteichoic acid synthesis in Streptococcus mutans results in acid sensitivity. J Bacteriol 2000; 182:6055-65. [PMID: 11029425 PMCID: PMC94739 DOI: 10.1128/jb.182.21.6055-6065.2000] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2000] [Accepted: 08/03/2000] [Indexed: 11/20/2022] Open
Abstract
In the cariogenic organism, Streptococcus mutans, low pH induces an acid tolerance response (ATR). To identify acid-regulated proteins comprising the ATR, transposon mutagenesis with the thermosensitive plasmid pGh9:ISS1 was used to produce clones that were able to grow at neutral pH, but not in medium at pH 5.0. Sequence analysis of one mutant (IS1A) indicated that transposition had created a 6.3-kb deletion, one end of which was in dltB of the dlt operon encoding four proteins (DltA-DltD) involved in the synthesis of D-alanyl-lipoteichoic acid. Inactivation of the dltC gene, encoding the D-alanyl carrier protein (Dcp), resulted in the generation of the acid-sensitive mutant, BH97LC. Compared to the wild-type strain, LT11, the mutant exhibited a threefold-longer doubling time and a 33% lower growth yield. In addition, it was unable to initiate growth below pH 6.5 and unadapted cells were unable to survive a 3-h exposure in medium buffered at pH 3.5, while a pH of 3.0 was required to kill the wild type in the same time period. Also, induction of the ATR in BH97LC, as measured by the number of survivors at a pH killing unadapted cells, was 3 to 4 orders of magnitude lower than that exhibited by the wild type. While the LTA of both strains contained a similar average number of glycerolphosphate residues, permeabilized cells of BH97LC did not incorporate D-[(14)C]alanine into this amphiphile. This defect was correlated with the deficiency of Dcp. Chemical analysis of the LTA purified from the mutant confirmed the absence of D-alanine-esters. Electron micrographs showed that BH97LC is characterized by unequal polar caps and is devoid of a fibrous extracellular matrix present on the surface of the wild-type cells. Proton permeability assays revealed that the mutant was more permeable to protons than the wild type. This observation suggests a mechanism for the loss of the characteristic acid tolerance response in S. mutans.
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Affiliation(s)
- D A Boyd
- Department of Oral Biology, University of Manitoba, Winnipeg, Manitoba, Canada
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Hyyryläinen HL, Vitikainen M, Thwaite J, Wu H, Sarvas M, Harwood CR, Kontinen VP, Stephenson K. d-Alanine Substitution of Teichoic Acids as a Modulator of Protein Folding and Stability at the Cytoplasmic Membrane/Cell Wall Interface of Bacillus subtilis. J Biol Chem 2000. [DOI: 10.1016/s0021-9258(19)61432-8] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Debabov DV, Kiriukhin MY, Neuhaus FC. Biosynthesis of lipoteichoic acid in Lactobacillus rhamnosus: role of DltD in D-alanylation. J Bacteriol 2000; 182:2855-64. [PMID: 10781555 PMCID: PMC101995 DOI: 10.1128/jb.182.10.2855-2864.2000] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/1999] [Accepted: 02/22/2000] [Indexed: 11/20/2022] Open
Abstract
The dlt operon (dltA to dltD) of Lactobacillus rhamnosus 7469 encodes four proteins responsible for the esterification of lipoteichoic acid (LTA) by D-alanine. These esters play an important role in controlling the net anionic charge of the poly (GroP) moiety of LTA. dltA and dltC encode the D-alanine-D-alanyl carrier protein ligase (Dcl) and D-alanyl carrier protein (Dcp), respectively. Whereas the functions of DltA and DltC are defined, the functions of DltB and DltD are unknown. To define the role of DltD, the gene was cloned and sequenced and a mutant was constructed by insertional mutagenesis of dltD from Lactobacillus casei 102S. Permeabilized cells of a dltD::erm mutant lacked the ability to incorporate D-alanine into LTA. This defect was complemented by the expression of DltD from pNZ123/dlt. In in vitro assays, DltD bound Dcp for ligation with D-alanine by Dcl in the presence of ATP. In contrast, the homologue of Dcp, the Escherichia coli acyl carrier protein (ACP), involved in fatty acid biosynthesis, was not bound to DltD and thus was not ligated with D-alanine. DltD also catalyzed the hydrolysis of the mischarged D-alanyl-ACP. The hydrophobic N-terminal sequence of DltD was required for anchoring the protein in the membrane. It is hypothesized that this membrane-associated DltD facilitates the binding of Dcp and Dcl for ligation of Dcp with D-alanine and that the resulting D-alanyl-Dcp is translocated to the primary site of D-alanylation.
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Affiliation(s)
- D V Debabov
- Department of Biochemistry, Molecular and Cell Biology, Northwestern University, Evanston, Illinois 60208, USA
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Baltz RH, Norris FH, Matsushima P, DeHoff BS, Rockey P, Porter G, Burgett S, Peery R, Hoskins J, Braverman L, Jenkins I, Solenberg P, Young M, McHenney MA, Skatrud PL, Rosteck PR. DNA sequence sampling of the Streptococcus pneumoniae genome to identify novel targets for antibiotic development. Microb Drug Resist 2000; 4:1-9. [PMID: 9533720 DOI: 10.1089/mdr.1998.4.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We initiated a survey of the Streptococcus pneumoniae genome by DNA sequence sampling. More than 9,500 random DNA sequences of approximately 500 bases average length were determined. Partial sequences sufficient to identify approximately 95% of the aminoacyl tRNA synthetase genes and ribosomal protein (rps) genes were found by comparing the database of partial sequences to known sequences from other organisms. Many genes involved in DNA replication, repair, and mutagenesis are present in S. pneumoniae. Genes for the major subunits of RNA polymerase are also present, as are genes for two alternative sigma factors, rpoD and rpoN. Many genes necessary for amino acid or cofactor biosynthesis and aerobic energy metabolism in other bacteria appear to be absent from the S. pneumoniae genome. A number of genes involved in cell wall biosynthesis and septation were identified, including six homologs to different penicillin binding proteins. Interestingly, four genes involved in the addition of D-alanine to lipoteicoic acid in other gram positive bacteria were found, even though the lipoteicoic acid in S. pneumoniae has not been shown to contain D-alanine. The S. pneumoniae genome contains a number of chaperonin genes similar to those found in other bacteria, but apparently does not contain genes involved in the type III secretion commonly observed in gram negative pathogens. The G+C content of S. pneumoniae genomic DNA is approximately 43 mole percent and the size of the genome is approximately 2.0 Mb as determined by pulsed-field gel electrophoresis. Many of the genes identified by sequence sampling have been physically mapped to the 19 different SmaI fragments derived from the S. pneumoniae genome. The database of random genome sequence tags (GSTs) provides the starting material for determining the complete genome sequence, gene disruption analysis, and comparative genomics to identify novel targets for antibiotic development.
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Affiliation(s)
- R H Baltz
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN 46285, USA
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Wecke J, Perego M, Fischer W. D-alanine deprivation of Bacillus subtilis teichoic acids is without effect on cell growth and morphology but affects the autolytic activity. Microb Drug Resist 2000; 2:123-9. [PMID: 9158734 DOI: 10.1089/mdr.1996.2.123] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Using insertional inactivation of the different genes of the dlt operon in Bacillus subtilis, we searched for metabolic and morphological changes caused by D-alanine ester deprivation of lipoteichoic acid and wall teichoic acid. There were no alterations of cell growth, basic metabolism, cellular content of phosphorus-containing compounds, ultrastructure, cell separation, and surface charge. The only alteration observed was an enhancement of endogenous and beta-lactam-induced cell lysis. Since this enhancement is doubtless correlated with the D-alanine ester deprivation of the teichoic acids, the present view based on in vitro experiments, that negatively charged LTA is inhibitory to autolysins, may be questioned. We propose that negatively charged lipoteichoic acid and/or wall teichoic acid serve in vivo to fix the cationic autolysins within the cell wall-membrane complex by electrostatic interaction. Positively charged D-alanine ester substituents decrease the binding capacity of the teichoic acids for autolysins by charge compensation.
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Affiliation(s)
- J Wecke
- Robert-Koch-Institut, Berlin, Germany
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Vaughan EE, Mollet B, deVos WM. Functionality of probiotics and intestinal lactobacilli: light in the intestinal tract tunnel. Curr Opin Biotechnol 1999; 10:505-10. [PMID: 10508641 DOI: 10.1016/s0958-1669(99)00018-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The commercial interest in functional foods that contain live microorganisms, also termed probiotics, is paralleled by increasing scientific attention to their functionality in the digestive tract. Most studies are focused on intestinal Lactobacillus species, which are part of the natural gastro-intestinal microbiota, and include analysis of colonisation factors and other interactions with the host, the design of novel or improved strains with specific health benefits, and the application of sophisticated molecular tools to determine their fate and activity in situ.
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Affiliation(s)
- E E Vaughan
- Laboratory of Microbiology Department of Biomolecular Sciences Hesselink van Suchtelenweg 4, 6703 CT, Wageningen, The Netherlands.
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Friedman M. Chemistry, nutrition, and microbiology of D-amino acids. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 1999; 47:3457-3479. [PMID: 10552672 DOI: 10.1021/jf990080u] [Citation(s) in RCA: 254] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Exposure of food proteins to certain processing conditions induces two major chemical changes: racemization of all L-amino acids to D-isomers and concurrent formation of cross-linked amino acids such as lysinoalanine. Racemization of L-amino acids residues to their D-isomers in food and other proteins is pH-, time-, and temperature-dependent. Although racemization rates of the 18 different L-amino acid residues in a protein vary, the relative rates in different proteins are similar. The diet contains both processing-induced and naturally formed D-amino acids. The latter include those found in microorganisms, plants, and marine invertebrates. Racemization impairs digestibility and nutritional quality. The nutritional utilization of different D-amino acids varies widely in animals and humans. In addition, some D-amino acids may be both beneficial and deleterious. Thus, although D-phenylalanine in an all-amino-acid diet is utilized as a nutritional source of L-phenylalanine, high concentrations of D-tyrosine in such diets inhibit the growth of mice. Both D-serine and lysinoalanine induce histological changes in the rat kidney. The wide variation in the utilization of D-amino acids is illustrated by the fact that whereas D-methionine is largely utilized as a nutritional source of the L-isomer, D-lysine is totally devoid of any nutritional value. Similarly, although L-cysteine has a sparing effect on L-methionine when fed to mice, D-cysteine does not. Because D-amino acids are consumed by animals and humans as part of their normal diets, a need exists to develop a better understanding of their roles in nutrition, food safety, microbiology, physiology, and medicine. To contribute to this effort, this multidiscipline-oriented overview surveys our present knowledge of the chemistry, nutrition, safety, microbiology, and pharmacology of D-amino acids. Also covered are the origin and distribution of D-amino acids in the food chain and in body fluids and tissues and recommendations for future research in each of these areas. Understanding of the integrated, beneficial effects of D-amino acids against cancer, schizophrenia, and infection, and overlapping aspects of the formation, occurrence, and biological functions of D-amino should lead to better foods and improved human health.
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Affiliation(s)
- M Friedman
- Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 800 Buchanan Street, Albany, California 94710, USA.
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50
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Clemans DL, Kolenbrander PE, Debabov DV, Zhang Q, Lunsford RD, Sakone H, Whittaker CJ, Heaton MP, Neuhaus FC. Insertional inactivation of genes responsible for the D-alanylation of lipoteichoic acid in Streptococcus gordonii DL1 (Challis) affects intrageneric coaggregations. Infect Immun 1999; 67:2464-74. [PMID: 10225909 PMCID: PMC115992 DOI: 10.1128/iai.67.5.2464-2474.1999] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/1998] [Accepted: 02/25/1999] [Indexed: 11/20/2022] Open
Abstract
Most human oral viridans streptococci participate in intrageneric coaggregations, the cell-to-cell adherence among genetically distinct streptococci. Two genes relevant to these intrageneric coaggregations were identified by transposon Tn916 mutagenesis of Streptococcus gordonii DL1 (Challis). A 626-bp sequence flanking the left end of the transposon was homologous to dltA and dltB of Lactobacillus rhamnosus ATCC 7469 (formerly called Lactobacillus casei). A 60-kb probe based on this flanking sequence was used to identify the homologous DNA in a fosmid library of S. gordonii DL1. This DNA encoded D-alanine-D-alanyl carrier protein ligase that was expressed in Escherichia coli from the fosmid clone. The cloned streptococcal dltA was disrupted by inserting an ermAM cassette, and then it was linearized and transformed into S. gordonii DL1 for allelic replacement. Erythromycin-resistant transformants containing a single insertion in dltA exhibited a loss of D-alanyl esters in lipoteichoic acid (LTA) and a loss of intrageneric coaggregation. This phenotype was correlated with the loss of a 100-kDa surface protein reported previously to be involved in mediating intrageneric coaggregation (C. J. Whittaker, D. L. Clemans, and P. E. Kolenbrander, Infect. Immun. 64:4137-4142, 1996). The mutants retained the parental ability to participate in intergeneric coaggregation with human oral actinomyces, indicating the specificity of the mutation in altering intrageneric coaggregations. The mutants were altered morphologically and exhibited aberrant cell septa in a variety of pleomorphs. The natural DNA transformation frequency was reduced 10-fold in these mutants. Southern analysis of chromosomal DNAs from various streptococcal species with the dltA probe revealed the presence of this gene in most viridans streptococci. Thus, it is hypothesized that D-alanyl LTA may provide binding sites for the putative 100-kDa adhesin and scaffolding for the proper presentation of this adhesin to mediate intrageneric coaggregation.
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MESH Headings
- Adhesins, Bacterial/genetics
- Adhesins, Bacterial/metabolism
- Amino Acid Sequence
- Bacterial Adhesion/genetics
- Bacterial Adhesion/physiology
- Base Sequence
- Cloning, Molecular
- DNA Primers/genetics
- DNA Transposable Elements/genetics
- DNA, Bacterial/genetics
- Genes, Bacterial
- Humans
- Microscopy, Electron
- Microscopy, Electron, Scanning
- Molecular Sequence Data
- Mouth/microbiology
- Mutagenesis, Insertional
- Sequence Homology, Amino Acid
- Streptococcus/genetics
- Streptococcus/metabolism
- Streptococcus/ultrastructure
- Teichoic Acids/biosynthesis
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Affiliation(s)
- D L Clemans
- Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, USA
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