Open AccessIdentification and characterization of a novel transcriptional regulator, MatR, for malonate metabolism in Rhizobium leguminosarum bv. trifolii
Author(s) -
Lee Hwan Young,
An Jae Hyung,
Kim Yu Sam
Publication year - 2000
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2000.01834.x
Subject(s) - biology , reporter gene , microbiology and biotechnology , promoter , electrophoretic mobility shift assay , luciferase , gene , biochemistry , transcription factor , gene expression , transfection
A novel gene, matR , located upstream of matABC, transcribed in the opposite direction, and encoding a putative regulatory protein by sequence analysis was discovered from Rhizobium leguminosarum bv. trifolii . The matA , matB, and matC genes encode malonyl‐CoA decarboxylase, malonyl‐CoA synthetase, and a presumed malonate transporter, respectively. Together, these enzymes catalyze the uptake and conversion of malonate to acetyl‐CoA. The deduced amino‐acid sequence of matR showed sequence similarity with GntR from Bacillus subtilis in the N‐terminal region encoding a helix‐turn‐helix domain. Electrophoretic mobility shift assay indicated that MatR bound to a fragment of DNA corresponding to the mat promoter region. The addition of malonate or methylmalonate increased the association of MatR and DNA fragment. DNase I footprinting assays identified a MatR binding site encompassing 66 nucleotides near the mat promoter. The mat operator region included an inverted repeat (TCTTGTA/TACACGA) centered −46.5 relative to the transcription start site. Transcriptional assays, using the luciferase gene, revealed that MatR represses transcription from the mat promoter and malonate alleviates MatR‐mediated repression effect on the expression of P mat ‐luc + reporter fusion.