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J. Bacteriol., Jul 1996, 3796-3802, Vol 178, No. 13
MM Nakano, P Zuber, P Glaser, A Danchin and FM Hulett
Bacillus subtilis can grow anaerobically in the presence of nitrate as a
terminal electron acceptor. The two component regulatory proteins, ResD and
ResE, and an anaerobic gene regulator, FNR, were previously shown to be
indispensable for nitrate respiration in B. subtilis. Unlike Escherichia
coli fnr, B. subtilis fnr transcription was shown to be highly induced by
oxygen limitation. fnr is transcribed from its own promoter as well as from
a promoter located upstream of narK, the first gene in the narK-fnr
dicistronic operon. DNA fragments containing the narK promoter, the fnr
promoter, and both of the promoters were used to construct three lacZ
fusions to examine the transcriptional regulation of the narK-fnr operon.
ResDE was found to be required for transcriptional activation of fnr from
the fnr-specific promoter, and FNR was required for activation of narK-fnr
transcription from the FNR- dependent narK operon promoter under
anaerobiosis. In order to determine if the requirement for ResDE in nitrate
respiration is solely to activate fnr transcription, fnr was placed under
control of the IPTG (isopropyl-beta-D-thiogalactopyranoside)-inducible
promoter, Pspac. The observed defect in anaerobic growth of a Pspac-fnr
delta resDE mutant in the presence of IPTG indicated that resDE has an
additional role in B. subtilis anaerobic gene regulation.
Copyright © 1996, American Society for Microbiology
Two-component regulatory proteins ResD-ResE are required for transcriptional activation of fnr upon oxygen limitation in Bacillus subtilis
Department of Biochemistry and Molecular Biology, Louisiana State University Medical Center, Shreveport, Louisiana 71130-3932, USA.
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