Open AccessThe upstream region of the nodD3 gene of Sinorhizobium meliloti carries enhancer sequences for the transcriptional activator NtrC
Author(s) -
Dusha Ilona,
Austin Sara,
Dixon Ray
Publication year - 1999
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1999.tb08768.x
Subject(s) - enhancer , sinorhizobium meliloti , activator (genetics) , promoter , transcription (linguistics) , biology , gene , footprinting , two component regulatory system , upstream activating sequence , regulation of gene expression , regulatory sequence , genetics , microbiology and biotechnology , gene expression , transcription factor , mutant , linguistics , philosophy
In Sinorhizobium meliloti the expression of the nodulation genes nodABC is regulated in response to the level of fixed nitrogen (ammonia). Previous results suggested that the response to the nitrogen status is mediated by the two‐component NtrB/NtrC system which controls transcription of the nodD3 gene, encoding a positive regulatory protein for the activation of nodABC transcription. Here we confirm by DNase I footprinting and gel shift assays that NtrC, when phosphorylated by NtrB, is able to interact with the enhancer sequences present upstream of nodD3 . A model is proposed whereby NtrC functions to control the transcription from the two promoters in the upstream region of nodD3 in response to nitrogen status.