Affiliation:
1. Trius Therapeutics, San Diego, California
Abstract
ABSTRACT
The biowarfare-relevant bacterial pathogen
Bacillus anthracis
contains two paralogs each of the
metS
and
murB
genes, which encode the important antibiotic target functions methionyl-tRNA synthetase and UDP-
N
-acetylenolpyruvoylglucosamine reductase, respectively. Empirical screens were conducted to detect and characterize gene fragments of each of these four genes that could cause growth reduction of
B. anthracis
when inducibly expressed from a plasmid-borne promoter. Numerous such gene fragments that were overwhelmingly in the antisense orientation were identified for the
metS1
and
murB2
alleles, while no such orientation bias was seen for the
metS2
and
murB1
alleles. Gene replacement mutagenesis was used to confirm the essentiality of the
metS1
and
murB2
alleles, and the nonessentiality of the
metS2
and
murB1
alleles, for vegetative growth. Induced transcription of RNA from
metS1
and
murB2
antisense-oriented gene fragments resulted in specific reduction of mRNA of their cognate genes. Attenuation of MetS1 enzyme expression hypersensitized
B. anthracis
cells to a MetS-specific antimicrobial compound but not to other antibiotics that affect cell wall assembly, fatty acid biosynthesis, protein translation, or DNA replication. Antisense-dependent reduction of MurB2 enzyme expression caused hypersensitivity to beta-lactam antibiotics, a synergistic response that has also been noted for the MurA-specific antibiotic fosfomycin. These experiments form the basis of mode-of-action detection assays that can be used in the discovery of novel MetS- or MurB-specific antibiotic drugs that are effective against
B. anthracis
or other gram-positive bacterial pathogens.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Cited by
15 articles.
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