SigC, the Group 2 Sigma Factor of RNA Polymerase, Contributes to the Late-stage Gene Expression and Nitrogen Promoter Recognition in the CyanobacteriumSynechocystissp. Strain PCC 6803

Munehiko ASAYAMA, Sousuke IMAMURA, Satoshi YOSHIHARA, Ai MIYAZAKI, Naoko YOSHIDA, Takashi SAZUKA, Takakazu KANEKO, Osamu OHARA, Satoshi TABATA, Takashi OSANAI, Kan TANAKA, Hideo TAKAHASHI (+1 others)
2004 Bioscience, biotechnology and biochemistry  
We examined the role of SigC (Sll0184), a sigma factor of RNA polymerase (RNAP), in a unicellular cyanobacterium, Synechocystis sp. strain PCC 6803. On the inactivation of sigC, which is an Escherichia coli rpoD homolog, cells were viable but had a low survival rate in the stationary phase of growth under normal physiological conditions, indicating that SigC is a group 2 type sigma factor. In analyses of transcript and protein levels using the sigC knockout strain, it was found that expression
more » ... nd that expression of glnB, a nitrogen key regulatory gene, is controlled by SigC in the stationary phase. Primer extension revealed that the glnB nitrogen promoter (P2) was specifically recognized by SigC in the stationary phase under conditions of nitrogen starvation. In vitro studies with purified enzymes indicated effective transcription, on supercoiled DNA templates, from P2 by SigC-RNAP with NtcA which is an activator for nitrogen gene transcription. DNase I footprinting also indicated binding and related sites of NtcA and/or RNAP with SigC on the nitrogen promoter. The unique promoter architecture and the mechanism of transcription by RNAP with SigC are also discussed.
doi:10.1271/bbb.68.477 pmid:15056876 fatcat:dfpuym24n5g7jiyfe2mu26ttfa