The tomato hexokinase LeHXK1 cloning, mapping, expression pattern and phylogenetic relationships
The tomato hexokinase LeHXK1 cloning, mapping, expression pattern and phylogenetic relationships
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DOI：
10.1016/s0168-9452(02)00166-8
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发表时间：
2002-09-01
期刊：
影响因子：
5.2
通讯作者：
Granot, D
中科院分区：
文献类型：
--
作者：
Dai, N;Kandel-Kfir, M;Granot, D
番茄（Lycopersicon esculentum L.）Mill.）从番茄果实cDNA文库中克隆了己糖激酶LeHXK1。功能互补的三突变酵母细胞（hxk1 hxk2 glk1），缺乏磷酸化葡萄糖和果糖的能力，证实了身份的LeHXK1作为己糖激酶。LeHXK1定位于番茄3号染色体，与定位于6号染色体的LeHXK2不同。有趣的是，LeHXK1的表达在叶片中非常低，而在年轻的番茄果实中非常高。从幼果提取物中分离出两种己糖激酶同工酶HXK1和HXK2，LeHXK1的同源物反义StHXK1敲除了HXK1同工酶，鉴定HXK1为LeHXK1的基因产物。真核生物和原核生物己糖磷酸化酶的系统发育分析表明，番茄己糖激酶基因，LeHXK1和LeHXK2，以及已知的真核生物己糖激酶和“葡萄糖激酶”属于同一个己糖激酶家族，其成员与细菌的葡萄糖特异性葡萄糖激酶无关。因此，这些数据表明，迄今为止还没有从植物、真菌或哺乳动物细胞中鉴定出真正的真核葡糖激酶。(C)2002爱思唯尔科学爱尔兰有限公司保留所有权利。
A tomato (Lycopersicon esculentum L. Mill.) hexokinase, LeHXK1, was cloned from a tomato fruit cDNA library. Functional complementation of triple-mutant yeast cells (hxk1 hxk2 glk1) that lack the ability to phosphorylate glucose and fructose confirmed the identity of LeHXK1 as a hexokinase. LeHXK1 was mapped to tomato chromosome 3-distinct from LeHXK2 which mapped to chromosome 6. Interestingly, expression of LeHXK1 was very low in leaves and very high in young tomato fruits. Two hexokinase isozymes, HXK1 and HXK2, were chromatographically separated from young fruit extracts, Antisense StHXK1 the homologue of, LeHXK1, knocked out the HXK1 isozyme, identifying HXK1 as the gene product of LeHXK1. Phylogenetic analysis of eukaryotic and prokaryotic hexose phosphorylating enzymes indicates that tomato hexokinase genes, LeHXK1 and LeHXK2, and the known eukaryotic hexokinases and 'glucokinases' belong to the same hexokinase family whose members are unrelated to the glucose-specific glucokinases of bacteria. Hence, the data suggest that thus far no true eukaryotic glucokinases have been identified, neither from plants, nor from fungi or mammalian cells. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.