Molecular evolution of the vertebrate hexokinase gene family: Identification of a conserved fifth vertebrate hexokinase gene
Molecular evolution of the vertebrate hexokinase gene family: Identification of a conserved fifth vertebrate hexokinase gene
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DOI：
10.1016/j.cbd.2007.11.002
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发表时间：
2008-03-01
影响因子：
3
通讯作者：
Tan, Huanran
中科院分区：
文献类型：
--
作者：
Irwin, David M.;Tan, Huanran
己糖激酶（HK）在糖进入细胞后立即磷酸化糖，使这些糖被代谢。在多种脊椎动物中共有四种己糖激酶——hki、HKII、HKIII和HKIV。HKIV通常被称为葡萄糖激酶（GCK），其分子量是其他己糖激酶的一半，因为它只有一个己糖激酶结构域，而其他脊椎动物的HKs则有两个。已经提出了不同的假说来解释己糖激酶基因家族的多样化。我们使用基因组方法来表征己糖激酶基因在不同的脊椎动物物种和近亲阵列。令人惊讶的是，我们发现了第五个己糖激酶样基因HKDC1，它存在并在多种脊椎动物中表达。对HKDC1的氨基酸序列分析表明它可能具有己糖激酶的功能。为了了解脊椎动物己糖激酶基因家族的进化，我们建立了所有脊椎动物己糖激酶基因的己糖激酶结构域的系统发育，以及来自脊椎动物近亲的己糖激酶基因。我们的系统发育表明，在己糖激酶基因家族多样化之前，己糖激酶结构域的重复产生了一个具有两个己糖激酶结构域的HK。我们还确定GCK是从一个含有两个己糖激酶结构域的基因进化而来的，但失去了它的n端己糖激酶结构域。我们还发现HKI和HKIII的酶功能发生了平行的变化。(C) 2007爱思唯尔公司版权所有。
Hexokinases (HK) phosphorylate sugar immediately upon its entry into cells allowing these sugars to be metabolized. A total of four hexokinases have been characterized in a diversity of vertebrates-HKI, HKII, HKIII, and HKIV HKIV is often called glucokinase (GCK) and has half the molecular weight of the other hexokinases, as it only has one hexokinase domain, while other vertebrate HKs have two. Differing hypothesis has been proposed to explain the diversification of the hexokinase gene family. We used a genomic approach to characterize hexokinase genes in a diverse array of vertebrate species and close relatives. Surprisingly we identified a fifth hexokinase-like gene, HKDC1 that exists and is expressed in diverse vertebrates. Analysis of the amino acid sequence of HKDC1 suggests that it may function as a hexokinase. To understand the evolution of the vertebrate hexokinase gene family we established a phylogeny of the hexokinase domain in all of the vertebrate hexokinase genes, as well as hexokinase genes from close relatives of the vertebrates. Our phylogeny demonstrates that duplication of the hexokinase domain, yielding a HK with two hexokinase domains, occurred prior to the diversification of the hexokinase gene family. We also establish that GCK evolved from a two hexokinase domain-containing gene, but has lost its N-terminal hexokinase domain. We also show that parallel changes in enzymatic function of HKI and HKIII have occurred. (C) 2007 Elsevier Inc. All rights reserved.