Proteomic analysis of the ATP synthase interactome in notothenioids highlights a pathway that inhibits ceruloplasmin production.

Antarctic notothenioids have unique adaptations that allow them to thrive in subzero Antarctic waters. Within the suborder Notothenioidei, species of the family Channichthyidae (icefish) lack hemoglobin and in some instances myoglobin too. In studies of mitochondrial function of notothenioids, few have focused specifically on ATP synthase. In this study, we find that the icefish has a significantly higher level of ATP synthase subunit α expression than the red-blooded , but a much smaller interactome than the other species. We characterize the interactome of ATP synthase subunit α in two red-blooded species , and in the icefish and and find that, in comparison with the other species, reactome enrichment for lacks chaperonin-mediated protein folding, and fewer oxidative-stress-associated proteins are present in the identified interactome of . Reactome enrichment analysis also identifies a transcript-specific translational silencing pathway for the iron oxidase protein ceruloplasmin, which has previously been reported in studies of icefish as distinct from other red-blooded fish and vertebrates in its activity and RNA transcript expression. Ceruloplasmin protein expression is detected by Western blot in the liver of , but not in , , and We suggest that the translation of ceruloplasmin transcripts is silenced by the identified pathway in icefish notothenioids, which is indicative of altered iron metabolism and Fe(II) detoxification.