BCHM 4116 1st Edition Lecture 26Outline of Last Lecture I. The structure and function of RNA polymerase II, the mRNA-synthesizing RNA polymeraseII. Transcription regulation in eukaryotes, including: Outline of Current Lecture I. Transcription initiation by RNA pol II requires TBP and GTFsCurrent LectureChapter 29: Transcription and Regulation of Gene Expression cont. #3i. Transcription initiation by RNA pol II requires TBP and GTFs1. The general transcription factors (GTFs) a. GTFs = TFIIA, TFIIB, TFIID, TFIIF, TFIIH, TFIISb. TFIID – TBPc. TFIIA – stabilizes TFIID and TATA boxd. TFIIB – recruits preinitiation complex (PIC) to promoter, positioning RNA pol active site over promotere. TFIIE & TFIIF – enhance promoter: PIC interaction f. TFIIH – helicase, aids in creating transcription bubble2. Mediatorsa. Bridge b/w enhancers & transcription co-activators to RNA pol at the promoterb. Ultimate regulator of transcription c. Acts as repressor and activator of transcription 3. Alleviating the repression due to nucleosomes a. Relief from repression imposed by chromatin structure requires factors that can reorganize chromatin & alter nucleosomes so that promoters become accessible to transcriptional machinery i. Chromatin-remodeling complexes1. Mediate ATP-dependent conformational noncovalent changes in nucleosome structures2. Nucleic acid stimulated multisubunit ATPaseii. Histone-modifying enezymesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1. Introduce covalent modifications into N-terminal tails of histone a. 1. Diminish DNA:histone associations via disruption of electrostatic interactionsb. 2. Introduce subsititutaions that can recruit binding of new protein participants through protein-protein interactionsb. Histone acetyl transferases (HATs)i. Acetylation of amino group on lysine residues in histone tails ii. N-acetylation suppresses positive charge in histone tails, diminishing their interaction w/ negatively charged DNAc. Transcription regulation: i. Phosphorylation of Ser residues ii. Methylation of Lys
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