CHARACTERIZATION OF THE NUCLEAR GENE ENCODING CHLOROPLAST RIBOSOMAL-PROTEIN S13 FROM ARABIDOPSIS-THALIANA

We have characterised a cDNA clone and a nuclear gene encoding the chl oroplast 30 s ribosomal protein S13 from Arabidopsis thaliana. The ide ntification is based on the high similarity of the predicted amino-aci d sequence with eubacterial S13 protein sequences, and immunodetection of a 14.5-kDa chloroplast ribosomal polypeptide using antibodies rais ed against the polypeptide produced from part of the cDNA expressed in bacteria. The predicted amino-acid sequence contains an N-terminal ex tension which has several features characteristic of chloroplast trans it peptides. Experiments suggest there is a single copy of this gene i n A. thaliana and multiple copies in Brassica species. The origin of t he mitochondrial S13 polypeptide in crucifers is also discussed.