Abstract
Chloroplast gene expression has been shown to be regulated at transcriptional level and also at various post-transcriptional steps, including RNA stabilization, RNA processing, RNA splicing and translation. We isolated Arabidopsis thaliana mutants pgr3 (proton gradient regulation 3) .The accumulation of Cytocrome b6f complex was affected in pgr3-1 and pgr3-2 but not in pgr3-3, while that of the NDH complex was in pgr3-1 and pgr3-3 but not in pgr3-2. PGR3 contains of 27 PPR (Pentatrico-Peptide Repeat) motifs. PPR motifs are present in proteins functioning in the post-transcriptional regulation of organellar gene expression.Actually,pgr3 defects impaired the stabilization of petL operon RNA and possibly also translation of petL and one of ndh genes. We determined the localization of PGR3 in the thylakoid membrane.These results suggest that PGR3 is involved in different steps of chloroplast RNA maturation for distinct target RNAs in the thylakoid membrane.
