In Vitro Reconstitution of Two Essential Steps in Wall Teichoic Acid Biosynthesis

ArticleinACS Chemical Biology 1(1):25-8 · March 2006with23 Reads
DOI: 10.1021/cb0500041 · Source: PubMed
Abstract
Wall teichoic acids (WTAs) are anionic polymers that decorate the cell walls of many gram-positive bacteria. These structures are essential for survival or virulence in many organisms, which makes the enzymes involved in their biosynthesis attractive targets for the development of new antibacterial agents. We present a strategy to obtain WTA biosynthetic intermediates that involves a combination of chemical and enzymatic transformations. Using these intermediates, we have reconstituted the first two committed steps in the biosynthetic pathway. This work enables the exploration of WTA-synthesizing enzymes as antibiotic targets.
    • "The GroP units are derived from CDP-glycerol, which is synthesized by TarD (Badurina et al. 2003). The >40 RboP units of the main chain are then polymerized by TarL (or a second enzyme termed TarK, see below) (Pereira et al. 2008; Ginsberg et al. 2006; Brown et al. 2008). These enzymes both prime the linkage unit and complete the main chain of the polymer (Brown et al. 2008; Fig. 5 Pathway for the biosynthesis of WTA in S. aureus. "
    [Show abstract] [Hide abstract] ABSTRACT: The major surface polysaccharides of Staphylococcus aureus include the capsular polysaccharide (CP), cell wall teichoic acid (WTA), and polysaccharide intercellular adhesin/poly-β(1-6)-N-acetylglucosamine (PIA/PNAG). These glycopolymers are important components of the staphylococcal cell envelope, but none of them is essential to S. aureus viability and growth in vitro. The overall biosynthetic pathways of CP, WTA, and PIA/PNAG have been elucidated, and the functions of most of the biosynthetic enzymes have been demonstrated. Because S. aureus CP and WTA (but not PIA/PNAG) utilize a common cell membrane lipid carrier (undecaprenyl-phosphate) that is shared by the peptidoglycan biosynthesis pathway, there is evidence that these processes are highly integrated and temporally regulated. Regulatory elements that control glycopolymer biosynthesis have been described, but the cross talk that orchestrates the biosynthetic pathways of these three polysaccharides remains largely elusive. CP, WTA, and PIA/PNAG each play distinct roles in S. aureus colonization and the pathogenesis of staphylococcal infection. However, they each promote bacterial evasion of the host immune defences, and WTA is being explored as a target for antimicrobial therapeutics. All the three glycopolymers are viable targets for immunotherapy, and each (conjugated to a carrier protein) is under evaluation for inclusion in a multivalent S. aureus vaccine. Future research findings that increase our understanding of these surface polysaccharides, how the bacterial cell regulates their expression, and their biological functions will likely reveal new approaches to controlling this important bacterial pathogen.
    Article · Jan 2016
    • "Engineering these modifications into intermediate analogues simplified their preparation and prevented aggregation in biochemical assays. Access to WTA substrate analogues has facilitated the characterization of several WTA biosynthetic enzymes from B. subtilis and S. aureus, including glycosyltransferases involved in: linkage unit formation [42,43], priming [43,45], polymerization [44,46] and modification [47,48]. However, many of these glycosyltransferases are membrane-associated and catalytically operate on undecaprenyl-linked substrates at the lipid–water interface in vivo. "
    [Show abstract] [Hide abstract] ABSTRACT: Some of the most successful drugs in the antibiotic pharmacopeia are those that inhibit bacterial cell wall biosynthesis. However, the worldwide spread of bacterial antibiotic resistance has eroded the clinical efficacy of these drugs and the antibiotic pipeline continues to be lean as drug discovery programs struggle to bring new agents to the clinic. Nevertheless, cell wall biogenesis remains a high interest and celebrated target. Recent advances in the preparation of chemical probes and biosynthetic intermediates provide the tools necessary to better understand cell wall assembly. Likewise, these tools offer new opportunities to identify and evaluate novel biosynthetic inhibitors. This review aims to highlight these advancements and to provide context for their utility as innovative new tools to study cell wall biogenesis and for antibacterial drug discovery. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Full-text · Article · Aug 2015
    • "Enzymes in this family are known to catalyze the transfer of a nucleotide diphosphate (NDP)-activated sugar to monoglycosylated Und-PP (i.e. lipid I) [44,45]. The product of this reaction is the phosphoglycolipid, Und-PPdisaccharide (i.e. "
    [Show abstract] [Hide abstract] ABSTRACT: In natural environments, bacteria often adhere to surfaces where they form complex multicellular communities. Surface adherence is determined by the biochemical composition of the cell envelope. We describe a novel regulatory mechanism by which the bacterium, Caulobacter crescentus, integrates cell cycle and nutritional signals to control development of an adhesive envelope structure known as the holdfast. Specifically, we have discovered a 68-residue protein inhibitor of holdfast development (HfiA) that directly targets a conserved glycolipid glycosyltransferase required for holdfast production (HfsJ). Multiple cell cycle regulators associate with the hfiA and hfsJ promoters and control their expression, temporally constraining holdfast development to the late stages of G1. HfiA further functions as part of a 'nutritional override' system that decouples holdfast development from the cell cycle in response to nutritional cues. This control mechanism can limit surface adhesion in nutritionally sub-optimal environments without affecting cell cycle progression. We conclude that post-translational regulation of cell envelope enzymes by small proteins like HfiA may provide a general means to modulate the surface properties of bacterial cells.
    Full-text · Article · Jan 2014
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