Hawkins A R, Gurr S J, Montague P, Kinghorn J R
Department of Biochemistry and Genetics, University of Newcastle upon Tyne, UK.
Mol Gen Genet. 1989 Jul;218(1):105-11. doi: 10.1007/BF00330572.
The nucleotide sequence of the Aspergillus nidulans gdhA gene encoding NADP linked glutamate dehydrogenase has been determined and Northern blot analysis used to study the regulation of expression of this gene. The gdhA gene is 1485 nucleotides long and, by comparison with the corresponding Neurospora crassa am gene, has two putative introns of 53 nucleotides and a protein encoding region of 1380 nucleotides that codes for an inferred protein of 49.63 kDa which shows regions of homology with glutamate dehydrogenase proteins from a range of organisms. mRNA analysis of wild-type mycelium grown under a variety of conditions shows that: (a) the highest levels are seen with glucose as the carbon source with inorganic nitrogen; and (b) no gdhA mRNA is detectable when cells are transferred to amino acids as sole carbon source, closely matching the observed glutamate dehydrogenase activity levels under identical conditions. The results presented strongly suggest that a good carbon source is a prerequisite for transcription, but the molecular mechanism responsible is unclear.
已确定构巢曲霉编码NADP连接谷氨酸脱氢酶的gdhA基因的核苷酸序列，并采用Northern印迹分析来研究该基因表达的调控。gdhA基因长1485个核苷酸，与相应的粗糙脉孢菌am基因相比，有两个53个核苷酸的推定内含子和一个1380个核苷酸的蛋白质编码区，该编码区编码一个推断分子量为49.63 kDa的蛋白质，该蛋白质与一系列生物体的谷氨酸脱氢酶蛋白显示出同源区域。对在各种条件下生长的野生型菌丝体进行的mRNA分析表明：（a）以葡萄糖作为无机氮的碳源时，gdhA mRNA水平最高；（b）当细胞转移到以氨基酸作为唯一碳源时，未检测到gdhA mRNA，这与在相同条件下观察到的谷氨酸脱氢酶活性水平密切匹配。所呈现的结果强烈表明，良好的碳源是转录的先决条件，但负责的分子机制尚不清楚。
