14 BIO 326R Regulatory RNA

14 BIO 326R Regulatory RNA - BIO 326R RNA chemistry,...

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BIO 326R RNA chemistry, Regulatory RNAs and gene expression February 25
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RNAse Within a cell, RNA is almost constantly synthesized, degraded and recycled. In contrast, DNA is rarely degraded RNase A - Ubiquitous enzyme Highly stable – survives boiling Very active, low sequence specificity Single strand specific – will degrade ds RNA given time RNA turnover is rapid RNA generally less stable molecule than DNA 2’ OH group on ribose can attack nearby Phosphate this is the mechanism underlying b ase hydrolysis and some RNAses
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O N CH 2 O - – P - O O N CH 2 PO 4 CH 2 PO 4 O H OH O N O N CH 2 PO 4 CH 2 PO 4 O - OH O N CH 2 OH O N CH 2 PO 4 CH 2 PO 4 OH O O CH 2 HO – P = O O O High Ph or Enzyme P O O O OH Base Hydrolysis of RNA 2’ 3’ cyclic phosphate 3’ 2’ Phosphorous is electropositive and attracts the negatively charged oxygen 3’ 2’ 2’ Hydroxyl group is deprotonated
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Structural (non-translated) RNAs In E. coli , ~95% of RNA is not translated Ribosomal RNA (rRNA) Transfer RNA (tRNA) Small nuclear RNAs (snRNA) Splicing factors in eukaryotes Regulatory RNAs Xist Large (18kb) untranslated RNA responsible for X inactivation in females Short length RNAs snRNAs – splicing factors in eukaryotic mRNA processing Other short length RNAs have recently discovered significant role siRNA, microRNA and small RNAs ~ 21 – 100 nt in length MicroRNA and small RNAs have regulatory functions, siRNA is an antiviral defense mechanism
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History of smaller RNAs RNAs below about 100 nt in length have traditionally been dismissed Difficult to deal with Degradation products Discovery of RNA interference First described in petunias in 1990 and
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This note was uploaded on 04/09/2009 for the course BIO 326R taught by Professor Whiteley during the Spring '08 term at University of Texas at Austin.

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14 BIO 326R Regulatory RNA - BIO 326R RNA chemistry,...

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