Structure, mechanism and evolution of chloroplast transfer RNA processing systems.
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.
University of Kansas, Department of Biochemistry, Lawrence 66045-2106, USA.
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Gegenheimer
D000818:Animals; D005075:Biological Evolution; D002736:Chloroplasts / Q000378:metabolism*; D004722:Endoribonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D012322:RNA Precursors / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D016337:RNA, Catalytic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018749:RNA, Plant / Q000378:metabolism*; D012343:RNA, Transfer / Q000096:biosynthesis*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D043262:Ribonuclease P; D012261:Ribonucleoproteins / Q000378:metabolism; D013768:Tetrahymena / Q000201:enzymology
D029968:Escherichia coli Proteins; D012322:RNA Precursors; D016337:RNA, Catalytic; D018749:RNA, Plant; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D012343:RNA, Transfer; D004722:Endoribonucleases; D043262:Ribonuclease P; C470865:ribonuclease P, E coli