Open AccessIn vivo activity of the nitrogen control transcription factor NtcA is subjected to metabolic regulation in Synechococcus sp. strain PCC 7942
Author(s) -
Luque Ignacio,
VázquezBermúdez María Félix,
PazYepes Javier,
Flores Enrique,
Herrero Antonia
Publication year - 2004
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.1574-6968.2004.tb09625.x
Subject(s) - operon , transcription (linguistics) , psychological repression , biology , gene , promoter , transcriptional regulation , transcription factor , regulation of gene expression , microbiology and biotechnology , repressor , gene expression , biochemistry , escherichia coli , linguistics , philosophy
Abstract The cyanobacterial protein NtcA is a global transcriptional regulator of genes involved in nitrogen assimilation that are subjected to ammonium‐promoted repression and is itself controlled by positive autoregulation. Strain CSI70 derived from Synechococcus sp. strain PCC 7942 was constructed to overexpress an additional ntcA gene copy from a constitutive promoter. This strain exhibited high levels of the NtcA protein both in the presence and in the absence of ammonium. However, expression of the NtcA‐dependent nir operon and glnA gene (tested by RNA/DNA hybridization and enzyme activity) was still subjected to nitrogen regulation. These results indicate in vivo regulation of the activity of NtcA at activation of transcription of nitrogen‐regulated genes as a function of the nitrogen status of the cell.