RNA polymerase during normal elongation 9.2 Transcription is catalyzed by RNA polymerase RNA polymerase is stalled backtracks 3'region of RNA is cleaved Cleavage Figure 9.6 A stalled New 3'end is located in catalytic site RNA polymerase can be released by cleaving the3￠end Catalytic site resumes elongation of RNA of the transcript. 清苇大当
Figure 9.6 A stalled RNA polymerase can be released by cleaving the 3￠ end of the transcript. 9.2 Transcription is catalyzed by RNA polymerase
9.3 RNA polymerase consists of multiple subunits Promoter is a region of DNA involved in binding of RNA polymerase to initiate transcription. Terminator is a sequence of DNA,represented at the end of the transcript,that causes RNA polymerase to terminate transcription. 情莘大当
Promoter is a region of DNA involved in binding of RNA polymerase to initiate transcription. Terminator is a sequence of DNA, represented at the end of the transcript, that causes RNA polymerase to terminate transcription. 9.3 RNA polymerase consists of multiple subunits
Temp late recognition: RNA polymerase binds to duplex DNA 9.3 RNA polymerase NN八入八八 consists of multiple DNA is unwound at pro moter subunits 八N八N八N Initiation:Chains of 2-9 bases are synthesized and released Figure 9.7 Transcription has 入八N八八 Elongati on:RNA polymerase synthesizes R NA four stages,which involve different types of interaction between RNA polymerase and Unwound region moves w ith RNA polymerase DNA.The enzyme binds to the promoter and melts DNA, RNA polymerase reaches end of gene remains stationary during initiation,moves along the 入入入入八怀 template durign elongation,and RNA polymerase and RNA are released dissociates at termination. 清苇大当
Figure 9.7 Transcription has four stages, which involve different types of interaction between RNA polymerase and DNA. The enzyme binds to the promoter and melts DNA, remains stationary during initiation, moves along the template durign elongation, and dissociates at termination. 9.3 RNA polymerase consists of multiple subunits
Gene product Functions 9.3 RNA polymerase enzyme assembly poA 2 o.subunits promoter recognition consists of multiple (40kD each) binds some activ ators subunits po8 B subunit (155kD) catalytic center rpoCB'subunit Figure 9.8 Eubacterial (160kD) RNA polymerases have s subunit four types of subunit,oa,β， poD(32-90 kD) promoter specifcity and B have rather constant sizes in different bacterial species,but o varies more 八八八 widely. E.coli enzyme 465 kD 清菜大当
Figure 9.8 Eubacterial RNA polymerases have four types of subunit; a, b, and b have rather constant sizes in different bacterial species, but s varies more widely. 9.3 RNA polymerase consists of multiple subunits
9.4 Sigma factor controls binding to DNA Sigma factor is the subunit of bacterial RNA polymerase needed for initiation; is the major influence on selection of binding sites (promoters). 清菜大当
Sigma factor is the subunit of bacterial RNA polymerase needed for initiation; is the major influence on selection of binding sites (promoters). 9.4 Sigma factor controls binding to DNA