Linked Life Data

9282745

Source:http://linkedlifedata.com/resource/pubmed/id/9282745

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1998-1-8
pubmed:databankReference
pubmed:abstractText
The dental pathogen Streptococcus mutans persists and causes diseases in highly dynamic environments and gains a selective ecological advantage in environmental conditions that frequently exceed the limits for growth of the organism, particularly with regard to environmental pH. The goal of this study was to begin a molecular genetic analysis of a major stress protein, DnaK/Hsp70, to begin to understand how stress responses are regulated in this lactic acid bacterium and to establish a relationship between dnaK gene expression and exposure to acidic environments. Cloning and nucleotide sequence analysis revealed that the dnaK gene is preceded by, and is in an operon-like arrangement with, the hrcA and grpE genes, although intergenic spacing was unlike that described in other bacteria. An inverted repeat (a CIRCE element) was identified by sequence analysis and, using primer extensions, a heat shock-responsive, sigmaA-type promoter, P1, 5' to the hrcA gene, and a sigmaB-type promoter, 5' to the grpE translational start site, were identified. No promoters were detected between grpE and dnaK. A strain carrying a strongly polar insertion in the hrcA gene had markedly diminished levels of dnaK mRNA, indicating that dnaK was transcribed as part of an operon from P1, and to a lesser extent from P2. Results from physiological manipulation of S. mutans in continuous chemostat culture demonstrated that steadystate levels of S. mutans dnaK mRNA and DnaK protein were (i) increased in response to acid shock; (ii) elevated in acid 'adapted' cells; and (iii) induced in response to alkali shock of acid 'adapted' cells. In all cases, increased amounts of dnaK mRNA could be correlated with enhanced transcription from P1. This study provides the first detailed analysis of the expression of a heat shock gene from an oral isolate, and the evidence provided suggests that sigmaB-like promoters may also be involved in class I heat shock gene expression in some Gram-positive organisms.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0950-382X
pubmed:author
pubmed:issnType
Print
pubmed:volume
25
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
329-41
pubmed:dateRevised
2009-7-17
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Transcriptional analysis of the Streptococcus mutans hrcA, grpE and dnaK genes and regulation of expression in response to heat shock and environmental acidification.
pubmed:affiliation
Department of Microbiology and Immunology, University of Rochester Medical Center, NY 14642, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.