Abstract
Two Candida albicans sterol mutants deficient in Δ8,7-isomerization and 5-desaturation, respectively, were studied in relation to those phenotypes associated with the 14α-demethylation deficiency, i.e. repression of hypha formation, inability to grow with non-fermentable substrates, and increased sensitivity to nonpolyene-nonazole chemicals. It was found that the Δ8,7-isomerization deficiency, resulting in the accumulation of Δ8 sterols (mostly Δ24(28) or Δ5,22), was associated with severe reduction in hyphal growth and utilization of non-fermentable substrates. These cellular activities were reduced only slightly when 5-desaturation was deficient, causing the accumulation of Δ7 sterols. On the other hand, both the isomerization and desaturation deficiencies were accompanied by multiple increases in drug sensitivity which were small in magnitude compared with those associated with the 14α-demethylation deficiency.