Fig 7. Functions of ERG251 and ERG25 in ergosterol metabolism.

C. albicans has two paralogs that specify C-4 sterol methyl oxidase, ERG251 and ERG25. Under planktonic conditions, either Erg251 or Erg25 is sufficient to support ergosterol synthesis. Under biofilm conditions, Erg251 is required for ergosterol synthesis at levels adequate for growth and filamentation. Biofilm conditions may impair ergosterol synthesis through limitation of oxygen and iron. ERG251 may be more critical than ERG25 for growth under biofilm conditions due to differences in expression levels, substrate affinities, catalytic rates, or ability to assemble into the C-4 demethylation complex [42,64] with Erg26, Erg27, and Erg28.