Novel mechanisms for maturation of chloroplast transfer RNA precursors.

摘要: Abstract Despite the prokaryotic origins of chloroplasts, a plant chloroplast tRNA precursor is processed in homologous vitro system by pathway distinct from that observed Escherichia coli, but identical to utilized for maturation nuclear pre-tRNAs. The mature 5' terminus generated site-specific endonucleolytic cleavage an RNase P (or P-type) activity. 3' end likewise produced single precise cut at encoded domain. This first complete structural characterization organellar processing using substrate. In contrast eubacterial P, does not appear contain RNA subunit. activity bands with bulk protein 1.28 g/ml CsCI density gradients, whereas E.coli as ribonucleoprotein 1.73 g/ml. Chloroplast survives treatment micrococcal nuclease (MN) levels 10- 100-fold higher than those required totally inactivate enzyme. sensitive suppression processing, caused binding inactive MN pre-tRNA substrate, which readily overcome addition carrier assay.