Title

Mutations in the Second Largest Subunit of RNA Polymerase II Cause 6-Azauracil Sensitivity in Yeast and Increased Transcriptional Arrest in Vitro

Document Type

Article

Publication Date

March 1996

Abstract

Yeast RNA polymerase II enzymes containing single amino acid substitutions in the second largest subunit were analyzed in vitro for elongation-related defects. Mutants were chosen for analysis based on their ability to render yeast cells sensitive to growth on medium containing 6-azauracil. RNA polymerase II purified from three different 6-azauracil-sensitive yeast strains displayed increased arrest at well characterized arrest sites in vitro. The extent of this defect did not correlate with sensitivity to growth in the presence of 6-azauracil. The most severe effect resulted from mutation rpb2-10(P1018S), which occurs in region H, a domain highly conserved between prokaryotic and eukaryotic RNA polymerases that is associated with nucleotide binding. The average elongation rate of this mutant enzyme is also slower than wild type. We suggest that the slowed elongation rate and an increase in dwell time of elongating pol II leads to rpb2-10's arrest-prone phenotype. This mutant enzyme can respond to SII for transcriptional read-through and carry out SII-activated nascent RNA cleavage.

Journal

Journal of Biological Chemistry

Volume

271

Issue

12

First Page

6866

Last Page

6873

Share

COinS