Abstract
Plastocyanin (PC) or cytochrome c6 (Cyt.c6) functions between cytochrome f and P700 in the photosynthetic electron transport system. In some green algae and cyanobacteria, PC accumulates in the cells grown with copper, whereas Cyt.c6 accumulates under copper-deficient conditions. We have investigated the structure and expression of PC gene in the green alga Eudorina elegans Ehrenberg var. elegans NIES-456 that shows reciprocal formation of PC and Cyt.c6. Partial sequence of the PC gene was determined by PCR and 3' RACE; the deduced amino acid sequence of Eudorina PC shows the highest homology with that for Chlamydomonas reinhardtii. Northern blot analysis using the PCR product as a probe showed that the amount of PC mRNA was reduced and the low molecular weight species of mRNA appeared under copper-deficient conditions, suggesting that the PC synthesis may be regulated at the level of mRNA stability.
