An unusual organization of the genes encoding cytochrome b(559) in Chlamydomonas reinhardtii: psbE and psbF genes are separately transcribed from different regions of the plastid chromosome
1995
Mor, T.S. | Ohad, I. | Hirschberg, J. | Pakrasi, H.B. (Hebrew Univ., Jerusalem (Israel). Inst. of Life Sciences. Dept. of Biological Chemistry)
The psbE and psbF genes encode the apoproteins of cytochrome b(559), an essential component of the pigment protein complex photosystem 2. Together with psbL and psbJ, these genes constitute a single operon in all photosynthetic organisms examined thus far. The psbE and psbF genes of the Chlamydomonas reinhardtii plastid genome were cloned and sequenced. The predicted amino-terminal domains of both polypeptides are more basic than those of other organisms, and the sequence of the psbE gene product indicates a departure from the 'positive-inside' rule for the insertion of proteins in the thylakoid membrane. Northern blot analysis demonstrated that psbE is transcribed into a 0.3 kb mRNA, while transcription of psbF and psbL genes results in a 0.9 kb transcript. The splitting of the psbEFLJ operon into separate transcription units suggests a unique mechanism of regulation of expression of these genes in C. reinhardtii.
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