ISSN:
1617-4623
Keywords:
Key words RNA polymerase
;
β′ subunit
;
NusA
;
Transcription termination
;
Rho factor
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Escherichia coli RNA polymerase is composed of four different subunits, α (present in two copies), β, β′ and σ. Among these, the β′ 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 β′, 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 β′ subunit. In vivo and in vitro transcription assays revealed that the rpoC10 allele of β′ 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 β′ subunit of E. coli RNA polymerase are involved in transcript termination or interaction with termination factor(s).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02174119
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