Affiliation:
1. Department of Microbiology and Molecular Genetics
2. Department of Entomology, Michigan State University, East Lansing, Michigan 48824
Abstract
ABSTRACT
Sequences that mediate the initiation of transcription in
Flavobacterium
species are not well known. The majority of identified
Flavobacterium
promoter elements show homology to those of other members of the phylum
Bacteroidetes
, but not of proteobacteria, and they function poorly in
Escherichia coli
. In order to analyze the
Flavobacterium
promoter structure systematically, we investigated the −33 consensus element, −7 consensus element, and spacer length of the
Flavobacterium ompA
promoter by measuring the effects of site-directed mutations on promoter activity. The nonconserved sequences in the spacer region and in regions close to the consensus motifs were randomized in order to determine their importance for promoter activity. Most of the base substitutions in these regions caused large decreases in promoter activity. The optimal −33/−7 motifs (TTTG/TANNTTTG) were identical to
Bacteroides fragilis
σ
ABfr
consensus −33/−7 promoter elements but lacked similarity to the
E. coli
σ
70
promoter elements. The length of the spacer separating the −33 and −7 motifs of the
ompA
promoter also had a pronounced effect on promoter activity, with 19 bp being optimal. In addition to the consensus promoter elements and spacer length, the GC content of the core promoter sequences had a pronounced effect on
Flavobacterium
promoter activity. This information was used to conduct a scan of the
Flavobacterium johnsoniae
and
B. fragilis
genomes for putative promoters, resulting in 188 hits in
B. fragilis
and 109 hits in
F. johnsoniae
.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
48 articles.
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