Part of the alcohol dehydrogenase multicomponent enzyme system which is involved in the production of acetic acid and in the ethanol oxidase respiratory chain. Does not play an obligatory role for the alcohol dehydrogenase (ADH) activity. The alcohol dehydrogenase multicomponent enzyme system is composed of a dehydrogenase subunit I (AdhA), a cytochrome c subunit II (AdhB) and a subunit III (AdhS).