Regulation of plastid gene transcription by sigma factor binding protein

摘要

Plastid sigma factors have four conserved regions homologous to those of bacterial class I and II sigma factors including E.coli sigma~(70). The function of each region of E.coli sigma~(70) has been detailed (Lonetto et al., 1992). The region 2 is divided into five subregions. The region 2.4 is responsible for the recognition of the -10 element and the region 2.5 recognizes the TGn motif found just upstream of the -10 element in some promoters. The region 4 is also divided into two subregions, and the region 4.2 recognizes the -35 element. In E.coli, many proteins interacting with the region 4 of sigma~(70) have been reported, e.g., Class II activators and anti-sigma~(70) factors. We expected the presence of the protein factors that selectively interact with each of the plastid sigma factors as to regulate their functions and decided to identify the factors which specifically interact with the region 4 of Arabidopsis thaliana Sig1 (At Sig1).