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Category: Bacterial Pathogenesis
Inhibitors of Peptidoglycan Biosynthesis, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555817794/9781555812584_Chap14-1.gif /docserver/preview/fulltext/10.1128/9781555817794/9781555812584_Chap14-2.gifAbstract:
The action of vancomycin and teicoplanin depends on their ability to bind specifically to the terminal D-alanyl-D-alanine group on the peptide side chain of the membrane-bound intermediates in peptidoglycan synthesis. Bacitracin was isolated in 1943 from a strain of a Bacillus sp., which was originally classified as Bacillus subtilis but now is known as Bacillus licheniformis. Binding of bacitracin prevents the enzymatic dephosphorylation of the lipid carrier molecule to its monophosphate form, a reaction which occurs during the second stage of peptidoglycan biosynthesis. Bacitracin is highly active against most gram-positive bacteria, particularly Staphylococcus aureus and Streptococcus pyogenes. Vancomycin binds reversibly to the D-Ala–D-Ala dipeptide segment of the muramyl pentapeptide present in peptidoglycan monomers which are exposed at the external cell surface of the cytoplasmic membrane. The dimeric structure of vancomycin is held together by four hydrogen bonds between the two amide backbones. Dimerization results in an enhanced antibacterial activity of vancomycin and other glycopeptides through cooperative binding effects. Vancomycin is the antibiotic of choice for serious infections caused by methicillinresistant S. aureus (MRSA) and coagulase-negative staphylococci, including methicillinresistant S. epidermidis. The development of glycopeptide antibiotics with activity against vancomycin- and teicoplanin-resistant organisms is of utmost importance because of the recent emergence of low-level vancomycin resistance in S. aureus and the prevelance of vancomycin-resistant enterococci (VRE) in immunocompromised patients.
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Schematic representation of the reactions at the cytoplasmic membrane during peptidoglycan synthesis in S. aureus. The sites of inhibition by bacitracin and the glycopeptides (vancomycin and teicoplanin) are indicated by large hollow arrows.
Schematic representation of the reactions at the cytoplasmic membrane during peptidoglycan synthesis in S. aureus. The sites of inhibition by bacitracin and the glycopeptides (vancomycin and teicoplanin) are indicated by large hollow arrows.
Chemical structures of vancomycin and of five teicoplanins.
Chemical structures of vancomycin and of five teicoplanins.
Chemical structure of bacitracin A.
Chemical structure of bacitracin A.
Chemical representation of the 1:1 complex between vancomycin and the dipeptide D-Ala–D-Ala from the muramyl pentapeptide pyrophosphoryl undecaprenol (lipid II).
Chemical representation of the 1:1 complex between vancomycin and the dipeptide D-Ala–D-Ala from the muramyl pentapeptide pyrophosphoryl undecaprenol (lipid II).
Reaction catalyzed by the transglycosylases at the outer surface of the cytoplasmic membrane. Reprinted from R. C. Goldman and D. Gange, Curr. Med. Chem. 7:801–820, 2000, with permission from the publisher.
Reaction catalyzed by the transglycosylases at the outer surface of the cytoplasmic membrane. Reprinted from R. C. Goldman and D. Gange, Curr. Med. Chem. 7:801–820, 2000, with permission from the publisher.
The hydrogen-bonding network in the vancomycin dimer. The peptide backbones of two molecules of vancomycin dimerize, forming four hydrogen bonds. In the structure shown in the figure, two units of the D-Ala–D-Ala ligand dock in the two binding pockets of the dimer through five hydrogen bonds each. Reprinted from D. A. Beauregard, A. J. Maguire, D. H. Williams, and P. E. Reynolds, Antimicrob. Agents Chemother. 41:2418–2423, 1997, with permission from the American Society for Microbiology.
The hydrogen-bonding network in the vancomycin dimer. The peptide backbones of two molecules of vancomycin dimerize, forming four hydrogen bonds. In the structure shown in the figure, two units of the D-Ala–D-Ala ligand dock in the two binding pockets of the dimer through five hydrogen bonds each. Reprinted from D. A. Beauregard, A. J. Maguire, D. H. Williams, and P. E. Reynolds, Antimicrob. Agents Chemother. 41:2418–2423, 1997, with permission from the American Society for Microbiology.
Schematic representation of the genes required for a high level of resistance to vancomycin in the VanA phenotype found within transposon Tn1546. The vanR, vanS, vanH, vanA, and vanX genes are essential for high-level resistance; the vanY and vanZ genes are nonessential. ORF1 and ORF2 encode proteins required for transposition. Reprinted from M. Arthur and P. Courvalin, Antimicrob. Agents Chemother. 37:1563–1571, 1993, with permission from the American Society for Microbiology.
Schematic representation of the genes required for a high level of resistance to vancomycin in the VanA phenotype found within transposon Tn1546. The vanR, vanS, vanH, vanA, and vanX genes are essential for high-level resistance; the vanY and vanZ genes are nonessential. ORF1 and ORF2 encode proteins required for transposition. Reprinted from M. Arthur and P. Courvalin, Antimicrob. Agents Chemother. 37:1563–1571, 1993, with permission from the American Society for Microbiology.
Illustration of vancomycin interacting with the peptidoglycan termini of vancomycin-sensitive bacteria (a) and vancomycin-resistant bacteria of the VanA phenotype (b). Adapted from V. L. Healy, E. S. Park, and C. T. Walsh, Chem. Biol. 5:197–207, 1998, with permission from the publisher.
Illustration of vancomycin interacting with the peptidoglycan termini of vancomycin-sensitive bacteria (a) and vancomycin-resistant bacteria of the VanA phenotype (b). Adapted from V. L. Healy, E. S. Park, and C. T. Walsh, Chem. Biol. 5:197–207, 1998, with permission from the publisher.
Pathway for the assembly of cytoplasmic peptidoglycan precursors. (a) Synthesis of UDP-muramyl pentapeptide in enterococci susceptible to glycopeptides. (b) Incorporation of D-lactate at the C-terminal position of peptidoglycan precursors of enterococci resistant to glycopeptides. There is an amide functional group in panel a and an ester functionality in the equivalent position in panel b.
Pathway for the assembly of cytoplasmic peptidoglycan precursors. (a) Synthesis of UDP-muramyl pentapeptide in enterococci susceptible to glycopeptides. (b) Incorporation of D-lactate at the C-terminal position of peptidoglycan precursors of enterococci resistant to glycopeptides. There is an amide functional group in panel a and an ester functionality in the equivalent position in panel b.
Illustration of vancomycin interacting with the peptidoglycan termini of vancomycin-sensitive bacteria (a) and mildly vancomycin-resistant bacteria of the VanC type (b). Adapted from V. L. Healy, E. S. Park, and C. T. Walsh, Chem. Biol. 5:197–207, 1998, with permission from the publisher.
Illustration of vancomycin interacting with the peptidoglycan termini of vancomycin-sensitive bacteria (a) and mildly vancomycin-resistant bacteria of the VanC type (b). Adapted from V. L. Healy, E. S. Park, and C. T. Walsh, Chem. Biol. 5:197–207, 1998, with permission from the publisher.
Figure 14.11 Chemical structures of vancomycin, LY264826, and its semisynthetic derivative LY333328. Reprinted from T. I. Nicas et al., Antimicrob. Agents Chemother. 39:2585–2597, 1995, with permission from the American Society for Microbiology.
Figure 14.11 Chemical structures of vancomycin, LY264826, and its semisynthetic derivative LY333328. Reprinted from T. I. Nicas et al., Antimicrob. Agents Chemother. 39:2585–2597, 1995, with permission from the American Society for Microbiology.
Chemical structures of teicoplanin and the related semisynthetic compounds MDL62,476 and MDL63,246. Commercial teicoplanin is a complex of five structurally related natural products that differ in the fatty acid acylating the glucosamine sugar. The most abundant component is shown. Reprinted from T. I. Nicas, M. L. Zeckel, and D. K. Braun, Trends Microbiol. 5:240–250, 1997, with permission from the publisher.
Chemical structures of teicoplanin and the related semisynthetic compounds MDL62,476 and MDL63,246. Commercial teicoplanin is a complex of five structurally related natural products that differ in the fatty acid acylating the glucosamine sugar. The most abundant component is shown. Reprinted from T. I. Nicas, M. L. Zeckel, and D. K. Braun, Trends Microbiol. 5:240–250, 1997, with permission from the publisher.
Generic and common trade names of bacitracin, the preparations available, and manufacturers in the United States
Generic and common trade names of bacitracin, the preparations available, and manufacturers in the United States
Phenotypic characteristics of glycopeptide-resistant enterococci a
Phenotypic characteristics of glycopeptide-resistant enterococci a