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TRNA integrity is a prerequisite for rapid CCA addition: implication for quality control.

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.

SUBMITTER: Dupasquier M

PROVIDER: S-EPMC2430420 | biostudies-literature | 2008 Jun

REPOSITORIES: biostudies-literature

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tRNA integrity is a prerequisite for rapid CCA addition: implication for quality control.

Dupasquier Marcel M Kim Sangbumn S Halkidis Konstantine K Gamper Howard H Hou Ya-Ming YM

Journal of molecular biology 20080408 3

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 Escherich ...[more]

PMID: 18466919

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