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J. Bacteriol., 08 1995, 4372-4376, Vol 177, No. 15
J Malakooti, SP Wang and B Ely
Caulobacter crescentus differentiates prior to each cell division to form
two different daughter cells: a monoflagellated swarmer cell and a
nonmotile stalked cell. Thus, one might expect that developmentally
expressed genes would be regulated by mechanisms different from those used
to regulate the expression of the biosynthetic genes. To determine a
consensus promoter sequence for genes involved in biosynthetic or
housekeeping functions, DNA fragments containing the regulatory regions of
the ilvD, ilvR, cysC, pleC, and fdxA genes were cloned. S1 nuclease
protection mapping and primer extension techniques were used to identify
the transcription initiation sites. Comparison of the regulatory regions of
these genes with those of the published sequences of the ilvBN, rrnA,
trpFBA, dnaA, dnaK, hemE, and rsaA genes has resulted in the identification
of a putative promoter consensus sequence. The -35 region contains the
sequence TTGACGS, which is similar to the Escherichia coli -35 region,
while the -10 region, GCTANAWC, has a more balanced GC content than the
corresponding region in E. coli. Oligonucleotide-directed site-specific
mutagenesis of both the ilvBN and pleC promoters indicates that mutations
that make a promoter more like the consensus result in increased promoter
activity, while mutations decreasing similarity to the consensus result in
decreased promoter activity.
Copyright © 1995, American Society for Microbiology
A consensus promoter sequence for Caulobacter crescentus genes involved in biosynthetic and housekeeping functions
Department of Biological Sciences, University of South Carolina, Columbia 29208, USA.
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