Structure,mechanism and evolution of chloroplast transfer RNA processing systems |
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Authors: | Peter Gegenheimer |
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Institution: | (1) Departments of Biochemistry and of Botany, and Molecular Genetics Program, The University of Kansas, 2045 Haworth Hall, 66045-2106 Lawrence, KS, USA |
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Abstract: | 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.Abbreviations pre-tRNA
precursor to tRNA
- pCp
cytidine 5 , 3 -bisphosphate
- IC50
inhibitor concentration giving 50% inhibition
- GAPDH
glyceraldehyde 3-phosphate dehydrogenase |
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Keywords: | catalytic mechanism endonuclease magnesium NADPH pathway protein RNase P |
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