Structure, mechanism and evolution of chloroplast transfer RNA processing systems

被引:20
作者
Gegenheimer, P
机构
[1] UNIV KANSAS,DEPT BOT,LAWRENCE,KS 66045
[2] UNIV KANSAS,MOL GENET PROGRAM,LAWRENCE,KS 66045
关键词
catalytic mechanism; endonuclease; magnesium; NADPH; pathway; protein; RNase P;
D O I
10.1007/BF00988720
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Chloroplasts of land plants have an active transfer RNA processing system, consisting of an RNase P-like 5' endonuclease, a 3' endonuclease, and a tRNA:CCA nucleotidyltransferase. The specificity of these enzymes resembles more that of their eukaryotic counterparts than that of their cyanobacterial predecessors. Most strikingly, chloroplast RNase P activity almost certainly resides in a protein, rather than in an RNA protein complex as in Bacteria, Archaea, and Eukarya. The chloroplast enzyme may have evolved from a preexisting chloroplast NADP-binding protein. Chloroplast RNase P cleaves pre-tRNA by a reaction mechanism in which at least one of the Mg2+ ions utilized by the bacterial ribozyme RNase P is replaced by an amino acid side chain.
引用
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页码:147 / 150
页数:4
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