Savouré A, Jaoua S, Hua X J, Ardiles W, Van Montagu M, Verbruggen N
Laboratorium voor Genetica, Universiteit Gent, Belgium.
FEBS Lett. 1995 Sep 18;372(1):13-9. doi: 10.1016/0014-5793(95)00935-3.
A full-length cDNA and the corresponding At-P5S gene encoding the first enzyme of the proline biosynthetic pathway, the delta 1-pyrroline-5-carboxylate (P5C) synthetase, were isolated in Arabidopsis thaliana. The At-P5S cDNA encodes a protein of 717 amino acids showing high identity with the P5C synthetase of Vigna aconitifolia. Strong homology is also found at the N-terminus to bacterial and yeast gamma-glutamyl kinase and at the C-terminus to bacterial gamma-glutamyl phosphate reductase. Putative ATP- and NAD(P)H-binding sites are suggested in the At-P5S protein. The transcribed region of the At-P5S gene is 4.8 kb long and contains 20 exons. Southern analysis suggests the presence of only one At-P5S gene in the A. thaliana genome mapped at the bottom of the chromosome two. Expression analysis of At-P5S in different organs reveals abundant At-P5S transcripts in mature flowering plant. Rapid induction of the At-P5S gene followed by accumulation of proline was observed in NaCl-treated seedlings suggesting that At-P5S is osmoregulated.
在拟南芥中分离出了一个全长cDNA以及相应的At-P5S基因，该基因编码脯氨酸生物合成途径的首个酶——δ1-吡咯啉-5-羧酸（P5C）合成酶。At-P5S cDNA编码一个由717个氨基酸组成的蛋白质，与豇豆的P5C合成酶具有高度同源性。在N端还发现与细菌和酵母的γ-谷氨酰激酶有很强的同源性，在C端与细菌的γ-谷氨酰磷酸还原酶有很强的同源性。在At-P5S蛋白中推测存在假定的ATP和NAD(P)H结合位点。At-P5S基因的转录区域长4.8 kb，包含20个外显子。Southern分析表明在拟南芥基因组中仅存在一个At-P5S基因，定位于第二条染色体的底部。对不同器官中At-P5S的表达分析显示，在成熟开花植物中有丰富的At-P5S转录本。在NaCl处理的幼苗中观察到At-P5S基因的快速诱导，随后脯氨酸积累，这表明At-P5S受渗透调节。
