MBIO 3410 lecture Sept 20 2007

MBIO 3410 lecture - Outline Last lecture DNA replication Bacterial DNA replication Initiation Elongation Termination DNA polymerases E coli DNA

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1 Outline- Last lecture DNA replication Bacterial DNA replication Initiation Elongation Termination DNA polymerases E. coli DNA polymerase III holoenzyme Eukaryotic DNA replication Prokaryotic DNA Transcription overview Initiation Elongation Termination Prokaryotic transcriptional unit E. coli RNA polymerase The E. coli σ70 promoter Prokaryote transcription initiation elongation termination
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2 Eukaryotic transcription Single genes are produced and regulated individually Activator and repressor at the 5’ end of a gene May have enhancers several thousands of bp upstream (req’d for full expression) Fig 1.22
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3 RNA polymerase II : Catalyzes the synthesis of mRNA (→protein) mRNA are processed through cap addition, poly(A) tail addition and intron splicing Promoters : Contain a TATA box 25-30 bp upstream of the start site Has a similar role to -10 sequence of E. coli promoters May also contain initiator elements rather than TATA box, they are located around the transcription start site Other promoters do not contain either of these elements, instead they contain GC-rich 20-50 bp region within the first 100-200 bp upstream of the start sites
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4 Eukaryotes have multiple RNA polymerase enzymes Eukaryotes have three different RNA polymerases responsible for the transcription of a certain class of genes Each polymerase is a large complex of proteins with 12 or more subunits Transcription occurs in a 5’ to 3’ direction synthesizing DNA complimentary to the antisense template strand
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5 RNA polymerase subunits All three eukaryotic RNA polymerases contain subunits that have homology (related DNA coding sequence) to E. coli RNA polymerase α 2 ββ’ Unlike E. coli RNA polymerase eukaryotic RNA polymerases require the presence of additional initiation proteins before they are able to bind promoters and initiate transcription www.steve.gb.com/science/transcription.html
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6 CTD of RNA polymerase II The carboxy end of RNA polymerase II contains a repeated stretch of 7 amino acids that are repeated Tyr-Ser-Pro-Thr-Ser-Pro-Ser is called the carboxyl-terminal domain (CTD) The CTD is unphosphorylated at transcription initiation and is phosphorylated (Ser and Tyr) as during transcription elongation www.steve.gb.com/science/transcription.html
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7 RNA polymerase II transcription factors: Required for transcription initiation from promoter sequences ( in vitro ) TFIID multicomplex protein binds the TATA box Consists of: TATA binding protein (TBP) and TBP-associated factors (TAF II s) TBP saddle-like structure which binds the minor groove of the
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This note was uploaded on 07/05/2008 for the course MBIO 3410 taught by Professor Richardson during the Fall '07 term at Manitoba.

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MBIO 3410 lecture - Outline Last lecture DNA replication Bacterial DNA replication Initiation Elongation Termination DNA polymerases E coli DNA

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