week_8_lecture_2

Function reflecting progression of lytic development

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Unformatted text preview: n cluster Lytic genes with related function, reflecting progression of lytic development progression • Transcription control in form of Transcription cascade in which gene expressed at one stage required for expression of genes in next stage genes Lewin Genes VII 2000 Oxford University Press Temporal control of transcription in phage SPO1 infected B. subtilis LYTIC CONTROL IN PHAGE T7 LYTIC • Phage T7 (38kb): 3 gene Phage classes expressed sequentially sequentially • Class I early genes: Class includes T7 RNAP includes • Class II genes: DNA Class replication genes transcribed by T7 RNAP transcribed • Class III genes: assembly Class genes for mature particle genes • Phage T4 (165kb): larger Phage phage with many gene groups groups Weaver 2002 Molecular Biology Ed. 2 PHAGE T4 GENE EXPRESSION PHAGE Lewin Genes VII 2000 Oxford University Press • • • • • T4 numbered genes – ESSENTIAL T4 ESSENTIAL T4 genes with 3-letter abbreviation - nonessential T4 nonessential T4 early genes: transcribed by host RNAP --> products include MotA T4 & AsiA AsiA Middle genes: lack -35 promoter consensus but transcribed by host Middle RNAP aided by MotA & AsiA RNAP MotA binding sites at -30 in middle gene promoters & AsiA coactivator interacting with E. coli σ 70 factor at -10 consensus activator E. PHAGE T4 GENE EXPRESSION PHAGE N antiterminator (works at nut site, permits replcation of delayed early genes) cro (control of repressor and other things) represses transcription, like the Lac repressor cI gene encodes λ repressor O and P code for proteins necessary for phage DNA replication Q is another antiterminator (works at qut site, permits replication of late genes) λ REGULATORY CONTROL: LYSIS vs. vs LYSOGENY LYSOGENY • When λ enters host, lysis When & lysogeny start off together the same way: immediate early & delayed early genes expressed early • LYSIS: if late genes LYSIS: expressed expressed • LYSOGENY: if λ repressor LYSOG...
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This note was uploaded on 03/26/2014 for the course MBB 321 taught by Professor Davidson during the Spring '11 term at Simon Fraser.

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