高等植物己糖激酶基因研究进展

Research Advances in the Hexokinase Gene Family in Higher Plant

己糖激酶(HXK)具有催化己糖磷酸化的作用,是植物体呼吸代谢过程中的关键酶之一。近十几年的研究发现,HXK在植物的糖感知和糖信号转导过程中扮演重要的角色。目前GenBank已登录28种高等植物的HXK同源基因,其在不同物种中均以多基因家族形式存在。HXK基因家族多数成员包括9个外显子,编码492-522个氨基酸。HXK亚细胞定位研究发现,植物HXK家族成员主要分布于线粒体,少数成员存在于细胞质、叶绿体和质体基质中。植物HXK基因家族大部分成员在不同器官或组织中均有表达,但是拟南芥(Arabidopsis thaliana)AtHKL3和水稻(Oryza sativa)OsHXK10仅在花中表达。高等植物部分HXK不仅影响植物生长发育,还调控植物激素信号转导以及调节植物花青素合成途径中相关基因表达。应用MEGA 4.0软件对18个物种HXK基因氨基酸序列构建系统进化树,HXK基因序列聚为7小支,聚类关系能反映不同基因结构和功能的差异。

Hexokinase（HXK）,one of the key enzymes in the process of plant respiration and metabolism,acts on hexose phosphorylating,and have been found to play a vital role in plant sugar sense and sugar signal transduction.Until present,HXK homologous genes sequence cloned from more than 20 species and the deduced protein sequence have been recorded in GenBank.HXKs exist in species as multi-gene family.Generally,HXK genes are comprised of 9 exons,coding 492-522 amino acids.Analysis of subcellular localization of HXKs reveals that majority of HXK are expressed preferentially in mitochondria,few in the cytosol,chloroplast and plastid-stroma.Most members mRNA are found in different organs or tissues,while AtHKL3 from Arabidopsis thaliana and OsHXK10 from Oryza sativa just express in flower.HXKs in higher plants involve in plant growth and development,phytohormone signal transduction and expression of genes related to anthocyanin biosynthesis.Phylogenetic evolutionary analyses of HXK amino acid sequences from 18 species were conducted with MEGA version 4.0.These sequences were divided into seven subgroups,and the result was in accord with discrepancy of HXK genes structure and function.