Transport of acidic amino acids in Candida albicans

Abstract

In Candida albicans ATCC 10261, two kinetically different amino acid transport systems with a high (S₁) and a low (S₂) affinity for aspartic acid (asp) and glutamic acid (glu) were identified. The S₁ for the two acidic amino acids was characterized by low K_t values while K_t values of S₂ were 30 to 40 times higher. Based on competitive studies of both systems, S₁ was found to be specific and common to both asp and glu while S₂ was relatively less specific. The S₁ and S₂ systems were also different in their sensitivity to respiratory inhibitors, mercurials and a K⁺ channel blocker. Both systems, however, showed maximum transport rates during the mid-exponential growth phase.