Affiliation:
1. Versicor, Inc., Fremont, California 94555
Abstract
ABSTRACT
Peptide deformylase, a bacterial enzyme, represents a novel target for antibiotic discovery. Two deformylase homologs,
defA
and
defB
, were identified in
Staphylococcus aureus
. The
defA
homolog, located upstream of the transformylase gene, was identified by genomic analysis and was cloned from chromosomal DNA by PCR. A distinct homolog,
defB
, was cloned from an
S. aureus
genomic library by complementation of the arabinose-dependent phenotype of a P
BAD
-def Escherichia coli
strain grown under arabinose-limiting conditions. Overexpression in
E. coli
of
defB
, but not
defA
, correlated to increased deformylase activity and decreased susceptibility to actinonin, a deformylase-specific inhibitor. The
defB
gene could not be disrupted in wild-type
S. aureus
, suggesting that this gene, which encodes a functional deformylase, is essential. In contrast, the
defA
gene could be inactivated; the function of this gene is unknown. Actinonin-resistant mutants grew slowly in vitro and did not show cross-resistance to other classes of antibiotics. When compared to the parent, an actinonin-resistant strain produced an attenuated infection in a murine abscess model, indicating that this strain also has a growth disadvantage in vivo. Sequence analysis of the actinonin-resistant mutants revealed that each harbors a loss-of-function mutation in the
fmt
gene. Susceptibility to actinonin was restored when the wild-type
fmt
gene was introduced into these mutant strains. An
S. aureus
Δ
fmt
strain was also resistant to actinonin, suggesting that a functional deformylase activity is not required in a strain that lacks formyltransferase activity. Accordingly, the
defB
gene could be disrupted in an
fmt
mutant.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Cited by
115 articles.
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