title: Enhancement of the frequency of initiation by a stimulatory protein of RNA polymerase II.
abstract: By use of purified RNA polymerase II, it was demonstrated that S-II, a stimulatory protein of RNA polymerase II, enhanced the frequency of initiation of transcription from discrete sites on the promoter region of the silk fibroin gene integrated in a supercoiled plasmid DNA in the presence of manganese. In the absence of S-II, RNA polymerase II preferentially initiated RNA synthesis from site +25, 25 bases downstream from the cap site. Of these initiation sites, the initiation from site +25 was not affected by S-II, suggesting that site +25 is structurally different from other initiation sites, including the cap site, and that S-II modifies the latter sites to the same structure as that of site +25. Direct interaction between S-II and DNA in the initiation complex was shown by demonstrating a conformational change of S-II on its interaction with DNA; namely, S-II in the initiation complex was as sensitive to chymotryptic digestion as S-II interacting with DNA, whereas free S-II was completely insensitive to chymotryptic digestion.
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000201:enzymology; D002918:Chymotrypsin; D004273:DNA, Neoplasm / Q000378:metabolism; D005349:Fibroins / Q000235:genetics; D011401:Promoter Regions, Genetic; D012313:RNA / Q000096:biosynthesis; D012319:RNA Polymerase II / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D004273:DNA, Neoplasm; D012313:RNA; D005349:Fibroins; D012319:RNA Polymerase II; D002918:Chymotrypsin