Open AccessInvolvement of the LuxR-Type Transcriptional Regulator RamA in Regulation of Expression of the gapA Gene, Encoding Glyceraldehyde-3-Phosphate Dehydrogenase of Corynebacterium glutamicum
Author(s) -
K. Toyoda,
Haruhiko Teramoto,
Masayuki Inui,
Hideaki Yukawa
Publication year - 2009
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.01425-08
Subject(s) - corynebacterium glutamicum , biology , gene , repressor , gene expression , glyceraldehyde 3 phosphate dehydrogenase , mutant , transcriptional regulation , regulation of gene expression , microbiology and biotechnology , promoter , biochemistry
SugR, RamA, GlxR, GntR1, and a MarR-type transcriptional regulator bind to the promoter region of thegapA gene encoding glyceraldehyde-3-phosphate dehydrogenase (GAPDH), essential for glycolysis inCorynebacterium glutamicum . We previously showed that SugR, a transcriptional repressor of phosphotransferase system genes for the sugar transport system, is involved in the downregulation ofgapA expression in the absence of sugar. In this study, the role of RamA in the expression of thegapA gene was examined. Comparing thegapA expression and GAPDH activity of aramA mutant with those of the wild type revealed that RamA is involved in upregulation ofgapA expression in glucose-grown cells. DNase I footprint analyses and electrophoretic mobility shift assays revealed that RamA binds with different affinities to three sites in thegapA promoter.lacZ reporter assays with mutated RamA binding sites in thegapA promoter showed that the middle binding site is the most important for RamA to activategapA expression and that binding of RamA to thegapA promoter activates the gene expression not only in glucose-grown cells but also in acetate-grown cells. Furthermore, RamA also directly activatessugR expression, indicating that two global regulators, RamA and SugR, are coordinately involved in the complex regulation ofgapA expression inC. glutamicum .