Journal of Bacteriology, February 1999, p. 1054-1058, Vol. 181, No. 3
Department of Biology, The University of
Michigan, Ann Arbor, Michigan 49109-1048
Received 11 September 1998/Accepted 16 November 1998
The lrp gene, which codes for the leucine-responsive
regulatory protein (Lrp), was cloned from Klebsiella
aerogenes W70. The DNA sequence was determined, and the clone was
used to create a disruption of the lrp gene. The lack of
functional Lrp led to an increased expression of the alanine catabolic
operon (dad) in the absence of the inducer
L-alanine but also to a decreased expression of the operon
in the presence of L-alanine. Thus, Lrp is both a repressor
and activator of dad expression. Lrp is also necessary for
glutamate synthase formation but not for the formation of two other
enzymes controlled by the nitrogen regulatory (Ntr) system, glutamate
dehydrogenase and histidase.
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Two Roles for the Leucine-Responsive Regulatory Protein in
Expression of the Alanine Catabolic Operon (dadAB) in
Klebsiella aerogenes
*
Corresponding author. Mailing address: Department of
Biology, The University of Michigan, Ann Arbor, MI 49109-1048. Phone: (734) 936-2530. Fax: (734) 647-0884. E-mail:
rbender{at}umich.edu.
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