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Updated: Jul 22, 2026

Isolation of Physiologically Active Thylakoids and Their Use in Energy-Dependent Protein Transport Assays
Published on: September 28, 2018
Structure, mechanism and evolution of chloroplast transfer RNA processing systems
1University of Kansas, Department of Biochemistry, Lawrence 66045-2106, USA.
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.
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