Affiliation:
1. Dows Institute for Research, University of Iowa College of Dentistry, Iowa City, Iowa 52242
2. Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas 66160
Abstract
ABSTRACT
Bacteria produce a variety of enzymes capable of methylating DNA. In many species, the majority of adenine methylation is accomplished by the DNA adenine methylase Dam. In
Escherichia coli
the Dam methylase plays roles in the initiation of replication, mismatch repair, and gene regulation. In a number of other bacterial species, mutation or overexpression of Dam leads to attenuation of virulence. Homologues of the
dam
gene exist in some members of the
Firmicutes
, including
Streptococcus mutans
, a dental pathogen. An
S. mutans
strain inactivated in the
dam
gene (SMU.504; here designated
damA
) was engineered, and phenotypes linked to cariogenicity were examined. A prominent observation was that the
damA
mutant produced greater amounts of glucan than the parental strain. Real-time PCR confirmed upregulation of
gtfB
. To determine whether other loci were affected by the
damA
mutation, a microarray analysis was carried out. Seventy genes were upregulated at least 2-fold in the
damA
mutant, and 33 genes were downregulated at least 2-fold. In addition to
gtfB
(upregulated 2.6-fold; 1.7-fold when measured by real-time PCR), other upregulated virulence factors included
gbpC
(upregulated 2.1-fold) and loci predicted to encode bacteriocins (upregulated 2- to 7-fold). Various sugar transport operons were also upregulated, the most extreme being the cellobiose operon (upregulated nearly 40-fold). Expression of
sacB
, encoding fructosyltransferase, was downregulated 2.4-fold. The sequence 5′-GATC-3′ appeared to constitute the recognition sequence for methylation. These results provide evidence that DNA methylation in
S. mutans
has a global effect on gene expression, including that of genes associated with cariogenic potential.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
20 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献