Localization of nusA-suppressing amino acid substitutions in the conserved regions of the beta' subunit of Escherichia coli RNA polymerase.
Escherichia coli RNA polymerase is composed of four different subunits, alpha (present in two copies), beta, beta' and sigma. Among these, the beta' polypeptide shares nine conserved regions with the largest subunits of eukaryotic RNA polymerases, but its role is poorly understood. We isolated novel mutations in a plasmid-borne copy of rpoC, which encodes beta', as dominant suppressors of two temperature-sensitive nusA alleles. All 20 suppressors of nusA11 (single missense mutation) isolated had either of two specific substitutions: Lys for Glu-402 (rpoC10) and Thr for Ala-904 (rpoC111) in the beta' subunit. In vivo and in vitro transcription assays revealed that the rpoC10 allele of beta' participates in Rho-dependent transcription termination. On the other hand, of 20 suppressors of nusA134 (deletion of C-terminal one-third) scattered at 18 distinct sites, 16 were assigned to one of six conserved regions C-I. These results suggested that the conserved domains of the beta' subunit of E. coli RNA polymerase are involved in transcript termination or interaction with termination factor(s).
Ito
K
K
Department of Tumor Biology, University of Tokyo, Japan.
Nakamura
Y
Y
D000483:Alleles; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D017124:Conserved Sequence / Q000235:genetics*; D012321:DNA-Directed RNA Polymerases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial / Q000235:genetics; D008969:Molecular Sequence Data; D010445:Peptide Elongation Factors; D017354:Point Mutation / Q000235:genetics; D012329:RNA, Bacterial / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D012234:Rho Factor / Q000502:physiology; D017384:Sequence Deletion; D013489:Suppression, Genetic / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics*; D035602:Transcriptional Elongation Factors
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D010445:Peptide Elongation Factors; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012234:Rho Factor; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors; C068727:nusA protein, E coli; D012321:DNA-Directed RNA Polymerases