Previous Article | Next Article ![]()
J. Bacteriol., 09 1997, 5903-5913, Vol 179, No. 18
A Haldimann, SL Fisher, LL Daniels, CT Walsh and BL Wanner
An Escherichia coli K-12 model system was developed for studying the
VanS-VanR two-component regulatory system required for high-level inducible
vancomycin resistance in Enterococcus faecium BM4147. Our model system is
based on the use of reporter strains with lacZ transcriptional and
translational fusions to the PvanR or PvanH promoter of the vanRSHAX gene
cluster. These strains also express vanR and vanS behind the native PvanR
promoter, the arabinose-inducible ParaB promoter, or the rhamnose-inducible
PrhaB promoter. Our reporter strains have the respective fusions stably
recombined onto the chromosome in single copy, thereby avoiding aberrant
regulatory effects that may occur with plasmid-bearing strains. They were
constructed by using allele replacement methods or a conditionally
replicative attP plasmid. Using these reporter strains, we demonstrated
that (i) the response regulator VanR activates PvanH, but not PvanR,
expression upon activation (phosphorylation) by the partner kinase VanS,
the noncognate kinase PhoR, or acetyl phosphate, indicating that
phospho-VanR (P-VanR) is a transcriptional activator; (ii) VanS interferes
with activation of VanR by PhoR or acetyl phosphate, indicating that VanS
also acts as a P- VanR phosphatase; and (iii) the conserved,
phosphate-accepting histidine (H164) of VanS is required for activation
(phosphorylation) of VanR but not for deactivation (dephosphorylation) of
P-VanR. Similar reporter strains may be useful in new studies on these and
other interactions of the VanS-VanR system (and other systems), screening
for inhibitors of these interactions, and deciphering the molecular logic
of the signal(s) responsible for activation of the VanS-VanR system in
vivo. Advantages of using an E. coli model system for in vivo studies on
VanS and VanR are also discussed.
Copyright © 1997, American Society for Microbiology
Transcriptional regulation of the Enterococcus faecium BM4147 vancomycin resistance gene cluster by the VanS-VanR two-component regulatory system in Escherichia coli K-12
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»