Surzycki S J, Shellenbarger D L
Proc Natl Acad Sci U S A. 1976 Nov;73(11):3961-5. doi: 10.1073/pnas.73.11.3961.
Two proteins with sigma-like activity have been isolated from the alga, Chlamydomonas reinhardi. One protein, sigma 2, has been partially purified and appears to have a molecular weight of 51,000. The interaction of this protein with a heterologous (Escherichia coli) and homologous (Chlamydomonas, chloroplast rifampicin-sensitive) core RNA-polymerase (RNA nucleotidyltransferase, nucleosidetriphosphate: RNA nucleotidyltransferase, EC 2.7.7.6) was studied. Sigma 2 protein appears to stimulate the formation of open (rapid starting) binary complexes by both of the core enzymes. Stimulation of transcription by sigma 2 on chloroplast DNA was greater when Chlamydomonas core enzyme was used. Moreover, in vitro transcription on a variety of templates using RNA polymerases I and II from Chlamydomonas was not stimulated by this protein.
已从莱茵衣藻中分离出两种具有类σ因子活性的蛋白质。其中一种蛋白质,即σ2,已得到部分纯化,其分子量似乎为51,000。研究了该蛋白质与异源(大肠杆菌)和同源(衣藻,叶绿体利福平敏感)核心RNA聚合酶(RNA核苷酸转移酶,核苷三磷酸:RNA核苷酸转移酶,EC 2.7.7.6)的相互作用。σ2蛋白似乎能刺激两种核心酶形成开放(快速起始)二元复合物。当使用衣藻核心酶时,σ2对叶绿体DNA转录的刺激作用更大。此外,该蛋白质不会刺激衣藻RNA聚合酶I和II对多种模板进行体外转录。