Cytochrome c (cyt) is important in oxidative phosphorylation as well as in apoptosis. This protein's cellular function is governed by its distinct conformations, which are influenced by interactions with cardiolipin (CL). Cyt has been studied extensively in mammals, but surprisingly not in nematodes. We have recombinantly expressed, purified and characterized the two C. elegans cytochromes CYC-2.1 and CYC-2.2. They are 83% homologous to each other and 62% and 61% homologous, respectively, to horse-heart cyt. Similar to mammalian cyt, CYC-2.1 and CYC-2.2 possess a-helical secondary and compact tertiary structures. Furthermore, the nematode proteins also have a methionine/histidine axial heme coordination and redox potentials in the range of 240-260 mV. Importantly, CYC-2.1 and CYC-2.2 both bind to membrane CL, whereupon they partially unfold and acquire peroxidase activity. Our results suggest that CYC-2.1 and CYC-2.2 can serve as useful models for studies of cyt-CL interactions both in vitro and in live C. elegans.

Biophysical characterization of <i>Caenorhabditis elegans</i> cytochromes

243rd National Meeting (2012)

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Biophysical characterization of Caenorhabditis elegans cytochromes