SUBUNITS OF YEAST RNA POLYMERASE-I INVOLVED IN INTERACTIONS WITH DNA AND NUCLEOTIDES

VALENZUELA, P; BULL, P; ZALDIVAR, J; VENEGAS, A; MARTIAL, J

SUBUNITS OF YEAST RNA POLYMERASE-I INVOLVED IN INTERACTIONS WITH DNA AND NUCLEOTIDES

Date

1978

Authors

Abstract

Reaction of yeast [Saccharomyces cerevisiae] RNA polymerase I with pyridoxal 5''-phosphate and sodium borohydride under conditions which inactivate the enzyme results in the specific binding of pyridoxal 5''-phosphate to subunits of 185,000, 137,000, 48,000 and 36,000 daltons. Nucleotides, which protect the enzyme from inactivation specifically inhibit the binding of pyridoxal 5''-phosphate to subunits of 185,000 and 137,000 daltons. DNA which also protects the enzyme from inactivation by pyridoxal 5''-phosphate prevents the binding of the reagent to the 4 polypeptides. These results suggest that subunits of 185,000 and 137,000 are involved in interactions with both nucleotides and DNA presumably of the type leading to initiation and/or polymerization and that subunits of 48,000 and 36,000 daltons also bind to DNA but this interaction is not strictly required for polymerase activity.