Structural Analysis and Expression during Dark-Light Transitions of a Gene for Cytochrome f in <italic>Chlamydomonas reinhardtii</italic><xref ref-type="fn" rid="fn1"><sup>1</sup></xref>

Abstract

The nucleotide sequence of a region of about 2.3 kb within the BamH 1-7 fragment of the ctDNA from Chlamydomonas reinhardtii was determined. Three open reading frames, ORF35, ORF62 and ORF317, were found in this region. These ORFs overlap one another and have different reading frames. ORF317 was identified as the petA gene which encodes cytochrome f preprotein. Six transcripts, ranging in size from 0.2 kb to 3.4 kb, hybridized to the DNA strand that contained pet A, and a 1.3-kb mRNA appeared to be a major transcript for cytochrome f. Expression of the petA gene was analyzed by Northern blotting and immunoblotting analysis, and a comparison was made between wild-type and y-1 mutant cells during dark-light transitions. The cytochrome f polypeptide was undetectable in both wild-type and y-1 cells grown in the dark and accumulated progressively after transfer to light. Steady-state levels of mRNA that encoded cytochrome f were nearly constant throughout the dark-light transitions in both wild-type and y-1 cells. The results suggest that the expression of pet A is regulated by light at the translational and /or post-translational levels.