Dehydration-induced tps gene transcripts from an anhydrobiotic nematode contain novel spliced leaders and encode atypical GT-20 family proteins
Dehydration-induced tps gene transcripts from an anhydrobiotic nematode contain novel spliced leaders and encode atypical GT-20 family proteins
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DOI：
10.1016/j.biochi.2005.01.010
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发表时间：
2005-06-01
期刊：
影响因子：
3.9
通讯作者：
Tunnacliffe, A
中科院分区：
文献类型：
--
作者：
Goyal, K;Browne, JA;Tunnacliffe, A
无脊椎动物，但这些生物中海藻糖生物合成基因的信息很少。我们在无水线虫中鉴定了两个海藻糖-6-磷酸合成酶（tps）基因，并确定了这两个基因的全长cDNA序列；为了进行比较，还获得了模型线虫秀丽隐杆线虫的全长tps cdna。A. avenae基因编码的蛋白质非常相似，含有GT-20糖基转移酶家族的催化结构域特征，与秀丽隐杆线虫的tps-2最相似；未发现黄连中存在与Ce-tps-1相对应的基因。对A. avenae tps cdna的分析揭示了几个感兴趣的特征，包括Aav-tps-1中剪接先导序列的选择性反式剪接，以及四个不同的新型SL1相关的反式剪接先导序列，它们与所有其他线虫中发现的典型SL1序列不同。后一种观察结果表明，A. avenae不符合在其他物种中观察到的严格的SL1序列进化保守。在预测的线虫TPS蛋白中也发现了不同寻常的特征，这将它们与其他高等真核生物（植物和昆虫）和微生物中的同源物区分开来。系统发育分析证实它们属于GT-20糖基转移酶家族，但表明分子进化速度加快。此外，线虫的TPS蛋白具有与其他真核生物无关的N-和c -末端结构域：例如，线虫的c -末端结构域不包含海藻糖-6-磷酸磷酸酶样序列，这在植物和昆虫的同源物中可见。在缺氧开始时，a . avenae的两个tps基因都上调，但暴露于寒冷或渗透压增加也会导致基因诱导，尽管程度较小。海藻糖似乎因此在线虫的许多应激反应中发挥作用。(c) 2005 Elsevier SAS。版权所有。
invertebrates, but there is little information on trehalose biosynthetic genes in these organisms. We have identified two trehalose-6-phosphate synthase (tps) genes in the anhydrobiotic nematode Aphelenchus avenae and determined full length cDNA sequences for both; for comparison, full length tps cDNAs from the model nematode, Caenorhabditis elegans, have also been obtained. The A. avenae genes encode very similar proteins containing the catalytic domain characteristic of the GT-20 family of glycosyltransferases and are most similar to tps-2 of C. elegans; no evidence was found for a gene in A. avenae corresponding to Ce-tps-1. Analysis of A. avenae tps cDNAs revealed several features of interest, including alternative trans-splicing of spliced leader sequences in Aav-tps-1, and four different, novel SL1-related trans-spliced leaders, which were different to the canonical SL1 sequence found in all other nematodes studied. The latter observation suggests that A. avenae does not comply with the strict evolutionary conservation of SL1 sequences observed in other species. Unusual features were also noted in predicted nematode TPS proteins, which distinguish them from homologues in other higher eukaryotes (plants and insects) and in micro-organisms. Phylogenetic analysis confirmed their membership of the GT-20 glycosyltransferase family, but indicated an accelerated rate of molecular evolution. Furthermore, nematode TPS proteins possess N- and C-terminal domains, which are unrelated to those of other eukaryotes: nematode C-terminal domains, for example, do not contain trehalose-6-phosphate phosphatase-like sequences, as seen in plant and insect homologues. During onset of anhydrobiosis, both tps genes in A. avenae are upregulated, but exposure to cold or increased osmolarity also results in gene induction, although to a lesser extent. Trehalose seems likely therefore to play a role in a number of stress responses in nematodes. (c) 2005 Elsevier SAS. All rights reserved.