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Abstract:
The terminal enzyme of the mitochondrial respiratory
chain, cytochrome oxidase, transfers electrons to
molecular oxygen, generating water. Within the
inner mitochondrial membrane, cytochrome oxidase
assembles into supercomplexes, together with other
respiratory chain complexes, forming so-called res-
pirasomes. Little is known about how these higher
oligomeric structures are attained. Here we report
on Rcf1 and Rcf2 as cytochrome oxidase subunits
in
S. cerevisiae
. While Rcf2 is specific to yeast,
Rcf1 is a conserved subunit with two human ortho-
logs, RCF1a and RCF1b. Rcf1 is required for growth
in hypoxia and complex assembly of subunits Cox13
and Rcf2, as well as for the oligomerization of a
subclass of cytochrome oxidase complexes into
respirasomes. Our analyses reveal that the cyto-
chrome oxidase of mitochondria displays intrinsic
heterogeneity with regard to its subunit composition
and that distinct forms of respirasomes can be
formed by complex variants.
