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J. Bacteriol., 06 1996, 3434-3439, Vol 178, No. 12
PG de Ruyter, OP Kuipers, MM Beerthuyzen, I van Alen-Boerrigter and WM de Vos
The promoters in the nisin gene cluster nisABTCIPRKFEG of Lactococcus
lactis were characterized by primer extension and transcriptional fusions
to the Escherichia coli promoterless beta-glucuronidase gene (gusA). Three
promoters preceding the nisA, nisR, and nisF genes, which all give rise to
gusA expression in the nisin-producing strain L. lactis NZ9700, were
identified. The transcriptional autoregulation of nisA by signal
transduction involving the sensor histidine kinase NisK and the response
regulator NisR has been demonstrated previously (0. P. Kuipers, M. M.
Beerthuyzen, P. G. G. A. de Ruyter, E. J. Luesink, and W. M. de Vos, J.
Biol. Chem. 270: 27299-27304, 1995), and therefore the possible
nisin-dependent expression of gusA under control of the nisR and nisF
promoters was also investigated. The nisR promoter was shown to direct
nisin-independent gusA expression in L. lactis MG 1363, which is a
nisin-transposon- and plasmid-free strain. L. lactis NZ9800, which does not
produce nisin because of a deletion in the nisA gene, containing the
nisF-gusA fusion plasmid, gave rise to beta- glucuronidase production only
after induction by nisin. A similar regulation was found in L. lactis
NZ3900, which contains a single copy of the nisR and nisK genes but no
other genes of the nisin gene cluster. In contrast, when the nisK gene was
disrupted, no beta- glucuronidase activity directed by the nisF promoter
could be detected even after induction with nisin. These results show that,
like the nisA promoter, the nisF promoter is nisin inducible. The nisF and
nisA promoter sequences have significant similarities and contain a
conserved region that could be important for transcriptional control.
Copyright © 1996, American Society for Microbiology
Functional analysis of promoters in the nisin gene cluster of Lactococcus lactis
Department of Biophysical Chemistry, Netherlands Institute for Dairy Research, Ede The Netherlands.
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