Regulation of chitin synthesis during germ-tube formation in Candida albicans.
The synthesis of chitin during germ-tube formation in Candida albicans may be regulated by the first and last steps in the chitin pathway: namely L-glutamine-D-fructose-6-phosphate aminotransferase and chitin synthase. Induction of germ-tube formation with either glucose and glutamine or serum was accompanied by a 4-fold increase in the specific activity of the aminotransferase. Chitin synthase in C. albicans is synthesized as a proenzyme. N-acetyl glucosamine increased the enzymic activity of the activated enzyme 3-fold and the enzyme exhibited positive co-operativity with the substrate. UDP-N-acetylglucosamine. Although chitin synthase was inhibited by polyoxin D (Ki = 1.2 microM) this antibiotic did not affect germination. During germ-tube formation the total chitin synthase activity increased 1.4-fold and the expressed activity (in vivo activated proenxyme) increased 5-fold. These results could account for the reported 5-fold increase in chitin content observed during the yeast to mycelial transformation.
D002176:Candida albicans / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D002238:Carbohydrate Epimerases / Q000378:metabolism*; D002686:Chitin / Q000096:biosynthesis*; D002687:Chitin Synthase / Q000378:metabolism*; D005636:Fructosephosphates / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D005964:Glucosyltransferases / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism; D005945:Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing) / Q000378:metabolism*
D005636:Fructosephosphates; D005973:Glutamine; D002686:Chitin; D005964:Glucosyltransferases; D002687:Chitin Synthase; D005945:Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing); D002238:Carbohydrate Epimerases; D005947:Glucose