Affiliation:
1. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
Abstract
ABSTRACT
Clostridium perfringens
is a Gram-positive anaerobic pathogen which causes many diseases in humans and animals. While some genetic tools exist for working with
C. perfringens
, a tightly regulated, inducible promoter system is currently lacking. Therefore, we constructed a plasmid-based promoter system that provided regulated expression when lactose was added. This plasmid (pKRAH1) is an
Escherichia coli-C. perfringens
shuttle vector containing the gene encoding a transcriptional regulator, BgaR, and a divergent promoter upstream of gene
bgaL
(
bgaR
-P
bgaL
). To measure transcription at the
bgaL
promoter in pKRAH1, the
E. coli
reporter gene
gusA
, encoding β-glucuronidase, was placed downstream of the P
bgaL
promoter to make plasmid pAH2. When transformed into three strains of
C. perfringens
, pAH2 exhibited lactose-inducible expression.
C. perfringens
strain 13, a commonly studied strain, has endogenous β-glucuronidase activity. We mutated gene
bglR
, encoding a putative β-glucuronidase, and observed an 89% decrease in endogenous activity with no lactose. This combination of a system for regulated gene expression and a mutant of strain 13 with low β-glucuronidase activity are useful tools for studying gene regulation and protein expression in an important pathogenic bacterium. We used this system to express the
yfp
-
pilB
gene, comprised of a yellow fluorescent protein (YFP)-encoding gene fused to an assembly ATPase gene involved in type IV pilus-dependent gliding motility in
C. perfringens
. Expression in the wild-type strain showed that YFP-PilB localized mostly to the poles of cells, but in a
pilC
mutant it localized throughout the cell, demonstrating that the membrane protein PilC is required for polar localization of PilB.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
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