| Literature DB >> 18466919 |
Marcel Dupasquier1, Sangbumn Kim, Konstantine Halkidis, Howard Gamper, Ya-Ming Hou.
Abstract
CCA addition to the 3' end is an essential step in tRNA maturation. High-resolution crystal structures of the CCA enzymes reveal primary enzyme contact with the tRNA minihelix domain, consisting of the acceptor stem and T stem-loop. RNA and DNA minihelices are efficient substrates for CCA addition in steady-state kinetics. However, in contrast to structural models and steady-state experiments, we show here by single-turnover kinetics that minihelices are insufficient substrates for the Escherichia coli CCA enzyme and that only the full-length tRNA is kinetically competent. Even a nick in the full-length tRNA backbone in the T loop, or as far away from the minihelix domain as in the anticodon loop, prevents efficient CCA addition. These results suggest a kinetic quality control provided by the CCA enzyme to inspect the integrity of the tRNA molecule and to discriminate against nicked or damaged species from further maturation.Entities:
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Year: 2008 PMID： 18466919 PMCID： PMC2430420 DOI： 10.1016/j.jmb.2008.04.005
Source DB: PubMed Journal: J Mol Biol ISSN： 0022-2836 Impact factor: 5.469