The structurally unique photosynthetic Chlorella variabilis NC64A hydrogenase does not interact with plant-type ferredoxins

摘要

Hydrogenases from green algae are linked to the photosynthetic electron transfer chain via the plant-type ferredoxin PetF. In this work the [FeFe]-hydrogenase from the Trebouxiophycean alga Chlorella variabilis NC64A (CvHydAl), which in contrast to other green algal hydrogenases contains additional FeS-cluster binding domains, was purified and specific enzyme activities for both hydrogen (H-2) production and H-2 oxidation were determined. Interestingly, although C. variabilis NC64A, like many Chlorophycean algal strains, exhibited light dependent H-2 production activity upon sulfur deprivation, CvHydAl did not interact in vitro with several plant type [2Fe-2S]-ferredoxins, but only with a bacterial2[4Fe4S]-ferredoxin. In an electrochemical characterization, the enzyme exhibited features typical of bacterial [FeFe]-hydrogenases (e.g. minor anaerobic oxidative inactivation), as well as of algal enzymes (very high oxygen sensitivity).