RNA-binding protein required for chloroplast 16S rRNA maturation, an important process which supports chloroplast gene expression and biogenesis. Binds to 16S rRNA precursor and is involved in its 5'-end processing (PubMed:24585838). May act as negative regulator of defense response against bacterial pathogens (PubMed:18003861). Down-regulated during infection with the bacterial pathogen Pseudomonas syringae pv. tomato avirulent avrRpt2 strain. Retarded growth and photobleaching phenotype (PubMed:18003861, PubMed:24585838). Enhanced resistance to the bacterial pathogen Pseudomonas syringae pv. tomato (PubMed:18003861).