Abstract:Staphylococcus
aureus
peptidoglycan (PG) is densely functionalized with anionic polymers called wall teichoic acids (WTAs). These polymers contain three tailoring modifications:
d
-alanylation, α-
O
-GlcNAcylation, and β-
O
-GlcNAcylation. Here we describe the discovery and biochemical characterization of a unique glycosyltransferase, TarS, that attaches β-
O
-GlcNAc (β-
O
… Show more
“…These glycosyltransferases catalyze the addition either α- or β-linked GlcNAc, respectively, to the repeating phospho-ribitol unit. 29,34 Using these strains, we tested the ability of the panel of four antibodies to bind S. aureus that displayed WTA containing either α- or β-linked GlcNAc. Flow cytometry analysis showed that three antibodies, 4462, 4497 and 6078, bound the S. aureus USA300 ΔtarM , but not the S. aureus USA300 ΔtarS strain (Figure 2A-C).…”
Section: Resultsmentioning
confidence: 99%
“…S. aureus WTA is synthesized by a group of eight enzymes found in the Tar (teichoic acid ribitol) operon, 24 with functionalization of the ribitol groups performed by the enzymes TarM and TarS (α-GlcNAc and β-GlcNAc) 25 and enzymes from the Dlt operon (D-alanyl ester) 26 (Figure 1). Importantly, S. aureus WTA has vital roles in colonization and virulence 27 with terminal modifications such as D-alanylation and β-O-GlcNAcylation required for resistance to anti-microbial peptides 28 and methicillin, 29 suggesting that the presence of WTA is essential for productive infection. Moreover, WTA has been shown to be a target of host antibody responses, 30,31 and therefore could be a target for antibody-based therapeutic development.10.1080/19420862.2018.1501252-F0001Figure 1.Schematic of S. aureus Wall Teichoic Acid (WTA) molecular structure.…”
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.
“…These glycosyltransferases catalyze the addition either α- or β-linked GlcNAc, respectively, to the repeating phospho-ribitol unit. 29,34 Using these strains, we tested the ability of the panel of four antibodies to bind S. aureus that displayed WTA containing either α- or β-linked GlcNAc. Flow cytometry analysis showed that three antibodies, 4462, 4497 and 6078, bound the S. aureus USA300 ΔtarM , but not the S. aureus USA300 ΔtarS strain (Figure 2A-C).…”
Section: Resultsmentioning
confidence: 99%
“…S. aureus WTA is synthesized by a group of eight enzymes found in the Tar (teichoic acid ribitol) operon, 24 with functionalization of the ribitol groups performed by the enzymes TarM and TarS (α-GlcNAc and β-GlcNAc) 25 and enzymes from the Dlt operon (D-alanyl ester) 26 (Figure 1). Importantly, S. aureus WTA has vital roles in colonization and virulence 27 with terminal modifications such as D-alanylation and β-O-GlcNAcylation required for resistance to anti-microbial peptides 28 and methicillin, 29 suggesting that the presence of WTA is essential for productive infection. Moreover, WTA has been shown to be a target of host antibody responses, 30,31 and therefore could be a target for antibody-based therapeutic development.10.1080/19420862.2018.1501252-F0001Figure 1.Schematic of S. aureus Wall Teichoic Acid (WTA) molecular structure.…”
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.
“…In the absence of WTA, Atl binding on the cell surface is delocalized, causing lysis (21). Furthermore, WTA are required for -lactam resistance in methicillin-resistant S. aureus, and the cells which lack WTA are sensitized to -lactam-induced cell lysis (26)(27)(28). The genes involved in teichoic acid biosynthesis are called the tar genes (for teichoic acid ribitol).…”
Section: Teixobactin-induced Lysis Is Dependent On the Atl Autolysinmentioning
Teixobactin represents the first member of a newly discovered class of antibiotics that act through inhibition of cell wall synthesis. Teixobactin binds multiple bactoprenol-coupled cell wall precursors, inhibiting both peptidoglycan and teichoic acid synthesis. Here, we show that the impressive bactericidal activity of teixobactin is due to the synergistic inhibition of both targets, resulting in cell wall damage, delocalization of autolysins, and subsequent cell lysis. We also find that teixobactin does not bind mature peptidoglycan, further increasing its activity at high cell densities and against vancomycin-intermediate Staphylococcus aureus (VISA) isolates with thickened peptidoglycan layers. These findings add to the attractiveness of teixobactin as a potential therapeutic agent for the treatment of infection caused by antibiotic-resistant Gram-positive pathogens.
“…Among antibioticresistant organisms, methicillin-resistant Staphylococcus aureus (MRSA) emerged early and presents one of the most serious challenges, a situation compounded by the extension of its range from being primarily a nosocomial problem to include community-acquired and livestock-associated spread (2,3). Novel strategies to combat MRSA are therefore urgently needed, and so it is notable that, in PNAS, Brown et al (4) have identified a surprising chink in the bacterial armor that may allow the development of novel therapeutic strategies to target MRSA.…”
mentioning
confidence: 99%
“…By using a TA null mutant (9) in comparison with a panel of S. aureus strain MW2 mutants lacking specific decorations of the TA, Brown et al (4) are able to dissect out the contribution of different TA structural features to various phenotypes associated with TA function. Most strikingly, they convincingly demonstrate that it is the TarS-mediated β-O-GlcNac modification of the TA that influences the MRSA phenotype.…”
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
