Temperature-related expression of the vacuolar aspartic proteinase (APR1) gene and beta-N-acetylglucosaminidase (HEX1) gene during Candida albicans morphogenesis.
Expression of the Candida albicans vacuolar aspartic proteinase (APR1) and beta-N-acetylglucosaminidase (HEX1) genes was studied when carbon-starved cells of strains ATCC 10261 and A72 were induced to grow as yeast or as germ tube-forming cells. Amounts of APR1 mRNA were similar under yeast or germ tube growth conditions. However, more APR1 mRNA was present in cells grown at 28 degrees C than in cells grown at 37 degrees C. The Apr1 enzyme activity of cell-free extracts was not affected by cellular morphology, culture pH or growth temperature. Amounts of HEX1 mRNA were also higher in N-acetylglucosamine (GlcNAc)-induced cells grown at 28 degrees C than in cells grown at 37 degrees C. There was slightly more HEX1 mRNA in cells grown at pH 4.5 than in cells grown at pH 6.7. The beta-N-acetylglucosaminidase activities of GlcNAc-grown cells correlated with the amounts of HEX1 mRNA and were higher when cells were grown at a lower temperature and at a lower pH. Although a similar temperature- and pH-dependent pattern of HEX1 mRNA expression was seen in cells grown on glucose, the enzyme activities in cell-free extracts were all very low. These data indicate that the APR1 and HEX1 genes play no direct role in the dimorphic transition of C. albicans and that transcription of both genes appears to be temperature regulated when the cells are released from carbon starvation. The expression of HEX1 mRNA is in part under the control of culture pH and translation of HEX1 mRNA seems to be regulated by glucose.
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Department of Oral Biology and Oral Pathology, University of Otago, Dunedin, New Zealand. masa.niimi@stonebow.otago.ac.nz
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D000118:Acetylglucosaminidase / Q000235:genetics* / Q000378:metabolism; D016282:Aspartic Acid Endopeptidases / Q000235:genetics* / Q000378:metabolism; D002176:Candida albicans / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D005800:Genes, Fungal; D009024:Morphogenesis; D012333:RNA, Messenger / Q000032:analysis; D013696:Temperature; D014617:Vacuoles / Q000201:enzymology*
D012333:RNA, Messenger; D000118:Acetylglucosaminidase; D016282:Aspartic Acid Endopeptidases