Lec13+notes

Lec13+notes - RNAs must often be processed to create a...

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Lecture 13 RNA Processing 1 RNAs must often be processed to create a functional gene product RNAs must eventually be degraded to allow changes in gene expression RNA is the “disposable” nucleic acid Kinds of RNA processing events Different nucleases, hydrolytic, phosphorolytic tRNA processing rRNA processing ModiFcation Splicing--different mechanisms Homing--a connection between transposition and introns
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Lecture 13 RNA Processing 2 Different RNA processing events are more or less prominent in different parts of the tree
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Lecture 13 RNA Processing 3 There are several kinds of RNA processing events. These include changes to: The 5’ end Position Addition or removal of phosphates, addition of methyl groups and or a "cap” Ligation of a “leader” RNA The 3' end Position Addition of oligoadenylate or oligouridylate residues Addition of CCA (tRNA) The middle Removal of chunks of sequence with rejoining (splicing) Adding and deleting new nucleotides (insertional editing) Changing the identity of speciFc nucleotides (editing) Adding methyl groups at speciFc positions in the chain (on base or sugar) Changing U to pseudoU at speciFc positions
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Lecture 13 RNA Processing 4 Endonucleolytic cleavage: RNAse III : specifc For dsRNA or stems RNase E : sequence specifc, activated by 5’monophosphate RNase P : cleaves 5’ leader oF RNAs SelF-cleaving ribozymes
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Lecture 13 RNA Processing 5 Exonucleolytic trimming: 3' specifc ribonucleases, oFten in a large complex with others: The degradosome (bacteria) The bacterial “degradosome” is a complex oF proteins · Polynucleotide phosphorylase (PNP): releases 5' ribonucleoside diphosphates, can add to 3’ end in reverse reaction · RhlB: An ATP-dependent RNA helicase · Enolase: a metabolic enzyme that acts as a scaFFold and is required For degradation oF glucose transporter mRNA in metabolic stress
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Lecture 13 RNA Processing 6 Transfer RNA (tRNA) processing in bacteria RNAse P is an endonuclease that cleaves pre-tRNA to form the 5' end tRNA is transcribed with extra RNA at the 5' end ( the leader ) RNAse P has an RNA subunit and a protein subunit (it is a ribonucleoprotein particle or RNP) The RNA is the catalytic subunit RNase F, and RNase D, two protein
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This note was uploaded on 01/17/2011 for the course BIOC 100A taught by Professor Harrynoller during the Fall '10 term at UCSC.

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Lec13+notes - RNAs must often be processed to create a...

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