Niimi M, Niimi K, Cannon R D
Department of Oral Biology and Oral Pathology, University of Otago, Dunedin, New Zealand.
FEMS Microbiol Lett. 1997 Mar 15;148(2):247-54. doi: 10.1111/j.1574-6968.1997.tb10296.x.
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.
当白色念珠菌菌株ATCC 10261和A72处于碳饥饿状态的细胞被诱导以酵母形式或形成芽管的细胞形式生长时，研究了其液泡天冬氨酸蛋白酶（APR1）和β-N-乙酰氨基葡萄糖苷酶（HEX1）基因的表达。在酵母或芽管生长条件下，APR1 mRNA的量相似。然而，在28℃生长的细胞中存在的APR1 mRNA比在37℃生长的细胞中更多。无细胞提取物的Apr1酶活性不受细胞形态、培养pH或生长温度的影响。在28℃生长的N-乙酰氨基葡萄糖（GlcNAc）诱导的细胞中，HEX1 mRNA的量也比在37℃生长的细胞中更高。在pH 4.5生长的细胞中比在pH 6.7生长的细胞中存在略多的HEX1 mRNA。GlcNAc生长的细胞的β-N-乙酰氨基葡萄糖苷酶活性与HEX1 mRNA的量相关，并且当细胞在较低温度和较低pH下生长时活性更高。尽管在葡萄糖上生长的细胞中观察到了类似的HEX1 mRNA表达的温度和pH依赖性模式，但无细胞提取物中的酶活性都非常低。这些数据表明，APR1和HEX1基因在白色念珠菌的双态转变中不发挥直接作用，并且当细胞从碳饥饿状态释放时，这两个基因的转录似乎受温度调节。HEX1 mRNA的表达部分受培养pH的控制，并且HEX1 mRNA的翻译似乎受葡萄糖调节。
