van Hartingsveldt W, van Zeijl C M, Harteveld G M, Gouka R J, Suykerbuyk M E, Luiten R G, van Paridon P A, Selten G C, Veenstra A E, van Gorcom R F
TNO Medical Biological Laboratory, Rijswijk, The Netherlands.
Gene. 1993 May 15;127(1):87-94. doi: 10.1016/0378-1119(93)90620-i.
Phytase catalyzes the hydrolysis of phytate (myo-inositol hexakisphosphate) to myo-inositol and inorganic phosphate. A gene (phyA) of Aspergillus niger NRRL3135 coding for extracellular, glycosylated phytase was isolated using degenerate oligodeoxyribonucleotides deduced from phytase amino acid (aa) sequences. Nucleotide (nt) sequence analysis of the cloned region revealed the presence of an open reading frame coding for 467 aa and interrupted once by an intron of 102 bp in the 5' part of the gene. The start codon is followed by a sequence coding for a putative signal peptide. Expression of phyA is controlled at the level of mRNA accumulation in response to inorganic phosphate levels. After cell growth in low-phosphate medium, a transcript of about 1.8 kb was visualized. Transcription of phyA initiates at at least seven start points within a region located 45-25 nt upstream from the start codon. In transformants of A. niger, expression of multiple copies of phyA resulted in up to more than tenfold higher phytase levels than in the wild-type strain.
植酸酶催化植酸盐（肌醇六磷酸）水解为肌醇和无机磷酸盐。利用从植酸酶氨基酸序列推导而来的简并寡脱氧核糖核苷酸，分离出了黑曲霉NRRL3135编码胞外糖基化植酸酶的基因（phyA）。对克隆区域的核苷酸序列分析显示，存在一个编码467个氨基酸的开放阅读框，且在基因5'端被一个102bp的内含子中断一次。起始密码子后接一段编码假定信号肽的序列。phyA的表达在mRNA积累水平上受无机磷酸盐水平的调控。在低磷酸盐培养基中细胞生长后，可观察到约1.8kb的转录本。phyA的转录在起始密码子上游45 - 25nt区域内的至少七个起始点开始。在黑曲霉转化体中，phyA多拷贝的表达导致植酸酶水平比野生型菌株高出十倍以上。
