Modification of tRNA anticodons plays a critical role in ensuring accurate translation. N4-acetylcytidine (ac4C) is present at the anticodon first position (position 34) of bacterial elongator tRNAMet. Herein, we identified Bacillus subtilis ylbM (renamed tmcAL) as a novel gene responsible for ac4C34 formation. Unlike general acetyltransferases that use acetyl-CoA, TmcAL activates an acetate ion to form acetyladenylate and then catalyzes ac4C34 formation through a mechanism similar to tRNA aminoacylation. The crystal structure of TmcAL with an ATP analog reveals the molecular basis of ac4C34 formation. The ÎtmcAL strain displayed a cold-sensitive phenotype and a strong genetic interaction with tilS that encodes the enzyme responsible for synthesizing lysidine (L) at position 34 of tRNAIle to facilitate AUA decoding. Mistranslation of the AUA codon as Met in the ÎtmcAL strain upon tilS repression suggests that ac4C34 modification of tRNAMet and L34 modification of tRNAIle act cooperatively to prevent misdecoding of the AUA codon. A comparative genomic approach identified a novel acetate-dependent tRNA-modifying enzyme that catalyzes RNA acetylation with a mechanism similar to tRNA aminoacylation. This modification maintains decoding fidelity in protein synthesis.
Kellerman, Journal of Biological Chemistry, 1958, vol. 231, p. 427,433-435
作者:Kellerman
DOI:——
日期:——
Berg, Journal of Biological Chemistry, 1956, vol. 222, p. 1015,1017
作者:Berg
DOI:——
日期:——
Characterization of Acyl Adenyl Anhydrides: Differences in the Hydrolytic Rates of Fatty Acyl-AMP and Aminoacyl-AMP Derivatives
作者:Otto F. Schall、Iwao Suzuki、Clare L. Murray、Jeffrey I. Gordon、George W. Gokel
DOI:10.1021/jo971874f
日期:1998.11.1
An improved procedure has been developed to prepare RCOOPO2-Ado (R = C6H13 and C15H31), the intermediate in the enzymatic synthesis of acyl-CoA's. The product has been characterized by spectral methods which, in turn, were used to define the hydrolysis rates of RCO-AMP. When R is a fatty acyl group, the hydrolysis rate is 10-fold slower than when R is aminoacyl. In both cases, the hydrolysis rate is enhanced by Mg2+. We speculate that the rate acceleration is due to intramolecular participation of the second carbonyl group in the aminoacyl residue.
Whitehouse et al., Journal of Biological Chemistry, 1957, vol. 226, p. 813,814