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There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
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Prof. Paul Agris, University of Albany
The importance of being modified: Tautomeric forms of pyrimidines provide expanded use of the genetic code
RiboEvo Seminar Series
Tautomeric shifts of 5-modified uridines have been established in E. coli tRNAValcmo5UAC as well as in the human cytoplasmic tRNALys3mcm5s2UUU. These shifts enable the recognition of multiple codons with the wobble base pair in the Watson-Crick geometry suggesting an energetic preference for, and perhaps enhanced efficiency with, this conformation. Thus, modifications at the 5-position of wobble position uridines appear to be a common mechanism for expanding tRNA’s codon recognition. One deviation from the universal code that is particularly interesting is the reading of AUG and the universal isoleucine codon AUA as methionine in both the A- and P-sites of the mitochondrial ribosome of most metazoans. We have established a mechanism by which 5-formylcytidine (f5C) at the wobble position of human mitochondrial tRNAMet (hmtRNAMetf5CAU) expands the decoding ability of this tRNA enabling it to read AUA as methionine. We have also found that another modified cytidine can restrict wobble base formation. This underscores the ability of cytidines, as well as uridine, modifications within the anticodon loop to modulate the decoding ability of the tRNA, providing insight into decoding mechanisms and evolution of the genetic code.
For more information contact Prof. Loren Williams (404-894-9752).
