Photosynthetic fuel for heterologous enzymes: the role of electron carrier proteins
Fifteen species from different genera of blue-green algae have been examined for their formation of plastocyanin (PC) and cytochrome c-553 (cyt c-553) in high or low Cu media. In addition to species which contain only cyt c-553 and those which completely exchange their cyt c-553 by PC, a new regulatory type was detected in which this exchange was incomplete. By comparing different species, it could be shown that either this incomplete exchange of cyt c-553 by PC as well as lack of PC in some other blue-green algae is not caused by restricted Cu uptake but is due to different biosynthetic and regulatory properties. Occurrence of PC and cyt c-553 cannot be used as a taxonomic criterium to classify blue-green algae. However, formation of either one or both of these redox components fits well into a line of evolution of the photosynthetic apparatus from the blue-green algae via green algae to higher plants.