Comparative studies of Bombyx mori nucleopolyhedrovirus chitinase and its host ortholog, BmChi-h
Comparative studies of Bombyx mori nucleopolyhedrovirus chitinase and its host ortholog, BmChi-h
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DOI：
10.1016/j.bbrc.2006.04.112
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发表时间：
2006-06-30
影响因子：
3.1
通讯作者：
Shimada, Toru
中科院分区：
文献类型：
--
作者：
Daimon, Takaaki;Katsuma, Susumu;Shimada, Toru
杆状病毒编码的几丁质酶（V-CHIA）首先被提出通过水平基因转移从细菌获得。然而，我们最近报道，鳞翅目宿主也编码v-chiA直系同源。在这里，我们描述了家蚕核型多角体病毒（BmNPV）几丁质酶及其宿主直系同源物，BmChi-h的比较研究。我们构建了重组BmNPV，其中天然和修饰形式的BmChi-h在多角体蛋白启动子下驱动，并且真正的v-chiA被删除。蛋白质印迹分析表明，BmCHI-h是迅速分泌的病毒感染的BmN细胞，而BmNPV CHIA是本地化的病毒感染的细胞内，可能是因为存在的C-末端内质网保留基序BmNPV CHIA。酶学研究表明，BmNPV CHIA在碱性条件下仍能保持较高的几丁质降解活性。为了B。用v-chiA缺失的BmNPV感染家蚕幼虫，没有观察到死亡幼虫的终末液化和杆状病毒编码的半胱氨酸蛋白酶的激活，并且BmChi-h的引入没有挽救这些缺陷。我们的研究结果表明，BmNPV chiA具有独特的功能，不共享的主机直系同源物，这可能反映了杆状病毒几丁质酶的功能专业化。
Baculovirus-encoded chitinases (V-CHIAs) were first proposed to be acquired from a bacterium via horizontal gene transfer. However, we have recently reported that lepidopteran hosts also encode v-chiA orthologs. Here we describe comparative studies of Bombyx mori nucleopolyhedrovirus (BmNPV) chitinase and its host ortholog, BmChi-h. We constructed recombinant BmNPVs in which native and modified forms of BmChi-h were driven under the polyhedrin promoter and the authentic v-chiA was deleted. Western blot analysis indicated that BmCHI-h was rapidly secreted from virus-infected BmN cells whereas BmNPV CHIA was localized within the virus-infected cells; probably because of the presence of a C-terminal endoplasmic reticulum retention motif on BmNPV CHIA. Enzymological studies showed that BmNPV CHIA was able to retain much higher chitinolytic activity under alkaline conditions. For B. mori larvae infected with v-chiA-deleted BmNPV, the terminal liquefaction of dead larvae and the activation of baculovirus-encoded cysteine protease were not observed, and the introduction of BmChi-h did not rescue these defects. Our findings show that BmNPV chiA possesses unique features that are not shared by host orthologs, which may reflect functional specialization of baculovirus chitinases.