Dimorphism-associated changes in amino acid transport of Candida albicans

Abstract

SUMMARYAmino acid uptake was followed during pHregulated dimorphism of Candida albicans. It was observed that transport activities of various amino acids differed with the morphological phenotype. The uptake rates of L-alanine, L-phenylalanine and of L-lysine were lower and those of Lmethionine were higher in elongated hypha (germ tube), while the rates of glycine, L-glutamic acid and L proline were similar in bud and hyphal phenotypes. Minimum threshold of amino acids transport activity is required at the time of phenotypic commitment in a diverging population of Candida albicans.

Levels of plasma membrane H+-ATPase do not change during growth and morphogenesis ofCandida albicans

“…The enzyme activity profile matches well with the overall growth and acidification of the external media of this organism (not shown). Our group has recently observed transient intracellular alkalinization and variations in the nutrient uptake during morphological transition of C. albicans [5,12]. Considering these findings and their relation to PM-ATPase activity, it became necessary to elucidate the role of this enzyme during growth and dimorphism of this yeast.…”

Lipids of Candida albicans

“…Only recently, studies related to nutrient transport and its relationship to morphogenesis of C. albieans have been initiated [43,67]. Very few reports are available where a role oflipids in transport systems of C. albieans has been implicated [67,68,69].…”

The Plasma Membrane of Candida albicans: Its Relevance to Transport Phenomenon

“…The rate of uptake of proline as compared to other amino acids was maximal in each population. However, since L-proline is a component of the differentiating media, its presence would have triggered the induction of its uptake [45]. The exact pool size of individual amino acids during morphogenesis of C. albicans is not known.…”

“…The fluctuation in amino acid uptake observed by us also did not match with changes in protein synthesis and the amino acid pool size of C. albicans. It has not been established whether the variations in transport activities of different amino acids are the cause of divergence, or whether they are simply an effect of differentiation [45].…”

“…Using the pH-regulated dimorphism method of SolI [98-100], we have recently studied the status of amino acid uptake during bud-to-hyphal transition [45]. It was observed that transport activities of various amino acids differed with the morphological phenotype.…”