title: Relationship between mRNA levels and protein accumulation in a chloroplast promoter-mutant of Chlamydomonas reinhardtii.
abstract: The photosynthetic chloroplast mutant G64 of Chlamydomonas reinhardtii was shown to contain a single point mutation within the 5' region of the psbD gene encoding the D2 protein of the photosystem II reaction center. The mutation affects the sequence element TATAATAT which has previously been hypothesized to function as the psbD promoter. Run-on analysis confirmed that transcription of psbD in the mutant was reduced to approximately 10% of the wild-type level. However, psbD mRNA accumulated to approximately 35%, despite the prominent decrease in RNA synthesis. This suggests that RNA-stabilization effects can compensate to some extent for a reduction in transcriptional activity. Interestingly, a direct correlation between transcript levels and the accumulation of the psbD gene product, the D2-protein, was observed in G64. The data suggest that posttranscriptionally acting regulatory factors determine the rate-limiting steps of chloroplast psbD gene expression.
authors.affiliation: Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Klinkert
authors.forename: Christian
authors.initials: C
authors.lastname: Schwarz
authors.forename: Stephan
authors.initials: S
authors.lastname: Pohlmann
authors.forename: Yves
authors.initials: Y
authors.lastname: Pierre
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Girard-Bascou
authors.forename: Jörg
authors.initials: J
authors.lastname: Nickelsen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000235:genetics*; D002736:Chloroplasts / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism*; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D012333:RNA, Messenger; D018749:RNA, Plant