Sajidan A, Farouk A, Greiner R, Jungblut P, Müller E-C, Borriss R
Department of Bacterial Genetics, Institute of Biology, Humboldt University, Chaussee-Strasse 117, 10115 Berlin, Germany.
Appl Microbiol Biotechnol. 2004 Jul;65(1):110-8. doi: 10.1007/s00253-003-1530-1. Epub 2004 Jan 16.
Klebsiella sp. strain ASR1 isolated from an Indonesian rice field is able to hydrolyse myo-inositol hexakis phosphate (phytate). The phytase protein was purified and characterised as a 42 kDa protein accepting phytate, NADP and sugar phosphates as substrates. The corresponding gene (phyK) was cloned from chromosomal DNA using a combined approach of protein and genome analysis, and expressed in Escherichia coli. The recombinant enzyme was identified as a 3-phytase yielding myo-inositol monophosphate, Ins(2)P, as the final product of enzymatic phytate hydrolysis. Based on its amino acid sequence, PhyK appears to be a member of a hitherto unknown subfamily of histidine acid phytate-degrading enzymes with the active site RHGXRXP and HD sequence motifs, and is different from other general phosphatases and phytases. Due to its ability to degrade sodium phytate to the mono phosphate ester, the phyK gene product is an interesting candidate for industrial and agricultural applications to make phytate phosphorous available for plant and animal nutrition.
从印度尼西亚稻田分离出的克雷伯氏菌属菌株ASR1能够水解肌醇六磷酸（植酸）。植酸酶蛋白被纯化，并被鉴定为一种42 kDa的蛋白质，它以植酸、NADP和糖磷酸作为底物。使用蛋白质和基因组分析相结合的方法从染色体DNA中克隆出相应的基因（phyK），并在大肠杆菌中表达。重组酶被鉴定为一种3-植酸酶，其产生的肌醇单磷酸（Ins(2)P）是植酸酶促水解的最终产物。基于其氨基酸序列，PhyK似乎是组氨酸酸性植酸降解酶一个迄今未知的亚家族的成员，具有活性位点RHGXRXP和HD序列基序，并且与其他普通磷酸酶和植酸酶不同。由于其能够将植酸钠降解为单磷酸酯，phyK基因产物是工业和农业应用中使植酸磷可供植物和动物营养利用的一个有趣候选物。
