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Preferential translation of chloroplast ribosomal proteins in Chlamydomonas reinhardtti

Conference · · Plant Physiol., Suppl.; (United States)
OSTI ID:6077873

The nuclear cr-1 mutant of C. reinhardtii is deficient in the 30S subunit of the chloroplast (cp) ribosome and in cp protein synthesis. The cp spectinomycin resistant mutant, spr-u-1-27-3, has a normal level of 70S ribosomes but only a low rate of cp protein synthesis with spectinomycin present. In both mutants there is little accumulation of the large subunit of ribulose 1,5-bisphosphate carboxylase (Rubisco LSU), but near wild-type levels of cp synthesized r-proteins. In cells pulse-labelled with /sup 35/SO/sub 4/ and immunoprecipitated with specific antisera, the ratio of the rate of synthesis of cp r-proteins to that of Rubisco LSU is 7 times greater in both mutants than in wild-type. No difference in the rate of turnover between r-proteins and Rubisco LSU in mutant and wild-type cells was observed during a one hour chase. The mRNA levels for r-protein L1 and Rubisco LSU actually increase slightly in the mutants. These data suggest that C. reinhardtii has a translation mechanism for preferential synthesis of cp r-proteins that operates under conditions of reduced total cp protein synthesis.

Research Organization:
Duke Univ., Durham, NC
OSTI ID:
6077873
Report Number(s):
CONF-8707108-
Journal Information:
Plant Physiol., Suppl.; (United States), Journal Name: Plant Physiol., Suppl.; (United States) Vol. 83:4; ISSN PPYSA
Country of Publication:
United States
Language:
English