CHLOROPLAST STRUCTURE AND FUNCTION IN ac-20, A MUTANT STRAIN OF CHLAMYDOMONAS REINHARDI III. Chloroplast Ribosomes and Membrane Organization
نویسنده
چکیده
The fine structure of the ac-20 strain of Chlamydomonas reinhardi is described . Cells grown mixotrophically in the presence of acetate have a highly disordered chloroplast membrane organization and usually lack pyrenoids. Chloroplast ribosome levels are only 5-10% of wild-type levels. Cells grown phototrophically without acetate possess more chloroplast ribosomes and have more normal membrane and pyrenoid organization . Chloroplast ribosome levels rise rapidly when cells are transferred from acetate to minimal medium, whereas membrane reorganization occurs only after a lag . These results, combined with earlier studies of the photosynthetic properties of the mutant strain, suggest that proper membrane organization, Photosystem II activity, and ribulose-1 ,5-diphosphate carboxylase formation are dependent on the presence of chloroplast ribosomes . Other chloroplast components tested are unaffected by a 10-fold reduction in levels of chloroplast ribosomes .
منابع مشابه
The Effects of Inhibitors of Rna and Protein Synthesis on Chloroplast Structure and Function in Wild-type Chlamydomonas Reinhardi
Wild-type cells of the unicellular green alga Chlamydomonas reinhardi have been grown for several generations in the presence of rifampicin, an inhibitor of chloroplast DNA-dependent RNA polymerase, spectinomycin and chloramphenicol, two inhibitors of protein synthesis on chloroplast ribosomes, and cycloheximide, an inhibitor of protein synthesis on cytoplasmic ribosomes. The effects of cyclohe...
متن کاملCHLOROPLAST STRUCTURE AND FUNCTION IN ac-20, A MUTANT STRAIN OF CHLAMYDOMONAS REINHARDI
A mutant strain of the green alga Chlamydomonas reinhardi, ac-20, is described in which both the rate of CO(2) fixation by whole cells and the rate of carboxylation of ribulose-1,5-diphosphate in cell-free extracts are reduced, particularly when sodium acetate is present in the growth medium. Of the enzymes of the reductive pentose phosphate cycle tested, only ribulose-1,5-diphosphate carboxyla...
متن کاملCharacterization of the EYE2 gene required for eyespot assembly in Chlamydomonas reinhardtii.
The unicellular biflagellate green alga Chlamydomonas reinhardtii can perceive light and respond by altering its swimming behavior. The eyespot is a specialized structure for sensing light, which is assembled de novo at every cell division from components located in two different cellular compartments. Photoreceptors and associated signal transduction components are localized in a discrete patc...
متن کاملProteomic characterization of the small subunit of Chlamydomonas reinhardtii chloroplast ribosome: identification of a novel S1 domain-containing protein and unusually large orthologs of bacterial S2, S3, and S5.
To understand how chloroplast mRNAs are translated into functional proteins, a detailed understanding of all of the components of chloroplast translation is needed. To this end, we performed a proteomic analysis of the plastid ribosomal proteins in the small subunit of the chloroplast ribosome from the green alga Chlamydomonas reinhardtii. Twenty proteins were identified, including orthologs of...
متن کاملComplete sequence of Euglena gracilis chloroplast DNA.
We report the complete DNA sequence of the Euglena gracilis, Pringsheim strain Z chloroplast genome. This circular DNA is 143,170 bp, counting only one copy of a 54 bp tandem repeat sequence that is present in variable copy number within a single culture. The overall organization of the genome involves a tandem array of three complete and one partial ribosomal RNA operons, and a large single co...
متن کامل