Transcriptional activation of NtcA-dependent promoters of Synechococcus sp. PCC 7942 by 2-oxoglutarate in vitro.
The transcription factor NtcA is a global regulator of nitrogen homeostasis in cyanobacteria. It thus positively regulates the expression of genes related to nitrogen assimilation such as glnA (which encodes glutamine synthetase) and ntcA itself in response to nitrogen shortage or depletion. The binding of NtcA to the glnA and ntcA promoters of Synechococcus sp. PCC 7942 in vitro now has been shown to be enhanced by 2-oxoglutarate. In vitro analysis of gene transcription also revealed that the interaction of NtcA with its promoter element was not sufficient for activation of transcription, and 2-oxoglutarate was required for transcriptional initiation by NtcA. Given that the intracellular concentration of 2-oxoglutarate is inversely related to nitrogen availability, it is proposed that this metabolite functions as a signaling molecule that transmits information on cellular nitrogen status to NtcA and thereby regulates the transcription of genes related to nitrogen assimilation in cyanobacteria.
Tanigawa
Ryohei
R
Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-0032, Japan.
Shirokane
Masao
M
Maeda Si
Shin-ichi
S
Omata
Tatsuo
T
Tanaka
Kan
K
Takahashi
Hideo
H
D001426:Bacterial Proteins; D000458:Cyanobacteria / Q000235:genetics*; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005974:Glutamate-Ammonia Ligase / Q000235:genetics; D007656:Ketoglutaric Acids / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation / Q000187:drug effects*
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D007656:Ketoglutaric Acids; D014157:Transcription Factors; C075617:ntcA protein, Synechococcus; D004247:DNA; D005974:Glutamate-Ammonia Ligase