Interference expression at levels of the transcript and protein among group 1, 2, and 3 sigma factor genes in a cyanobacterium

The sigma (σ) factor is a subunit for the RNA polymerase (RNAP) holoenzyme and can confer promoter selectivity at a target gene. On the inactivation of all group 2 and 3 σ factor genes, expression at the level of the transcript and protein was examined under continuous white light at an exponential phase in a unicellular cyanobacterium, Synechocystis sp. strain PCC 6803. It was found that interference expression exists among group 1, 2, and 3 σ factor genes. Authentic echoes of the expression did not always reflect correlations between the transcript and protein levels. Linkages for the expression network of the σ factors were summarized and unique properties discussed.