Molecular Genetics of Chloroplast Ribosomes In Chlamydomonas

Abstract

The green alga Chlamydomonas reinhardtii is an ideal model organism in which to investigate the cooperation of nuclear and chloroplast genomes in chloroplast ribosome formation from both developmental and evolutionary perspectives. Mutations affecting a variety of ribosomal components have been isolated and mapped genetically (see Boynton et al., 1990a and Harris, 1989 for reviews), and both the chloroplast (Boynton et al., 1988, 1990b; Blowers et al., 1989) and nuclear genomes (Debuchy et al., 1989; Kindle et al., 1989; Mayfield and Kindle, 1990; Diener et al., 1990) can be manipulated using newly developed transformation methods. In this paper we review our recent work on 1) the genetics and molecular biology of mutations to antibiotic resistance affecting the rRNA genes; 2) identification of chloroplast and nuclear genes encoding chloroplast ribosomal proteins (r-proteins); 3) expression of chloroplast genes encoding r-proteins; and 4) the transformation of chloroplast rRNA genes. We also outline the direction our current research is taking to define more precisely the rRNA-r-protein interactions involved in chloroplast ribosome biogenesis and function, as well as the molecular mechanisms involved in regulating expression of chloroplast r-protein genes.