Document Detail

Differential effects of nucleotide analogs on scanning-dependent initiation and elongation of mammalian mRNA translation in vitro.
MedLine Citation:
PMID:  20423978     Owner:  NLM     Status:  MEDLINE    
Codon-anticodon interactions are central to both the initiation and elongation phases of eukaryotic mRNA translation. The obvious difference is that the interaction takes place in the ribosomal A-site during elongation, whereas the 40S ribosomal subunit and associated initiation factors scan the mRNA sequence in search of an initiation codon with Met-tRNA(i) bound in the P-site, ceasing once codon-anticodon interaction is established at the AUG. As an indirect test of whether the two mechanisms of mRNA sequence inspection are basically similar or not, the effects of six different uridine analog substitutions in the mRNA were examined in reticulocyte lysate translation assays and 80S initiation complex formation assays. Four constructs, each with the same reporter coding sequence, were used, differing in whether the initiation codon was AUG or ACG, and in whether the 5'-UTR had U residues or not. Three analogs (5-bromoU, 5-aminoallylU, and pseudoU) inhibited both elongation and initiation, but the other three had striking differential effects. Ribothymidine had a negligible effect on elongation but caused a approximately 50% inhibition of initiation, with little effect on actual AUG recognition, which implies that inhibition must have occurred at some earlier step in initiation. In complete contrast, 2' deoxyU was prohibitive to elongation but had no effect on initiation, and 4-thioU actually stimulated initiation but quite strongly inhibited elongation processivity. These results show that the detailed mechanisms of inspection of the mRNA sequence during scanning-dependent initiation and elongation must be considerably different.
Julie L Aspden; Richard J Jackson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-04-27
Journal Detail:
Title:  RNA (New York, N.Y.)     Volume:  16     ISSN:  1469-9001     ISO Abbreviation:  RNA     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-05-24     Completed Date:  2010-07-07     Revised Date:  2013-05-29    
Medline Journal Info:
Nlm Unique ID:  9509184     Medline TA:  RNA     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1130-7     Citation Subset:  IM    
Department of Molecular and Cell Biology and Center of Integrative Genomics, University of California at Berkeley, Berkeley, CA 94720-3204, USA.
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MeSH Terms
Codon / genetics
Mammals / genetics
Protein Biosynthesis*
Pseudouridine / metabolism
RNA, Messenger / chemistry,  genetics*,  metabolism
Trinucleotide Repeats / genetics
Uridine / analogs & derivatives,  metabolism
Uridine Triphosphate / analogs & derivatives,  metabolism
Grant Support
062348//Wellcome Trust; //Medical Research Council
Reg. No./Substance:
0/Codon; 0/RNA, Messenger; 1445-07-4/Pseudouridine; 58-96-8/Uridine; 63-39-8/Uridine Triphosphate; KEY8PG1BRC/5-bromouridine

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