Utilizations of various uridine 5'-triphosphate analogues by DNA-dependent RNA polymerases I and II purified from liver nuclei of the cherry salmon (Oncorhynchus masou).
Various 5-substituted UTPs (methyl, ethyl, n-propyl, n-butyl, fluoro, chloro, bromo, and iodo) and sulfur-containing UTP analogues (4-thio-, 2-thio-, 5-methyl-2-thio-, and 5-methyl-4-thio-) were synthesized chemically and their utilization by DNA-dependent-RNA polymerases I and II of the cherry salmon (Oncorhynchus masou) were studied in substitution experiments under the condition of limited RNA synthesis in vitro. RNA polymerase I utilized the 5-methyl-, chloro, bromo, and iodo derivatives of UTP more efficiently than unmodified UTP, but RNA polymerase II utilized UTP most efficiently. 5-Methyl-4-thiouridine 5'-triphosphate (4-thio TTP) was utilized more efficiently than UTP by RNA polymerase I. On the other hand, it was found that 4-thio TTP was a selective substrate for RNA polymerase I and that its incorporation by RNA polymerase II was very slow. Thus recognition of UTP analogues as substrates by RNA polymerase I and II was different. These observation were attributed from kinetic analyses to differences in catalytic activity (Vmax).
D000818:Animals; D002467:Cell Nucleus / Q000201:enzymology; D055598:Chemical Phenomena; D002621:Chemistry; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D012318:RNA Polymerase I / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism*; D012474:Salmon; D013379:Substrate Specificity; D014500:Uracil Nucleotides; D014544:Uridine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism
D014500:Uracil Nucleotides; D012319:RNA Polymerase II; D012318:RNA Polymerase I; D014544:Uridine Triphosphate