The sialate-4-O-acetylesterases of coronaviruses related to mouse hepatitis virus:: a proposal to reorganize group 2 Coronaviridae
The sialate-4-O-acetylesterases of coronaviruses related to mouse hepatitis virus:: a proposal to reorganize group 2 Coronaviridae
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DOI：
10.1099/0022-1317-83-2-395
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发表时间：
2002-02-01
影响因子：
3.8
通讯作者：
Vlasak, R
中科院分区：
文献类型：
--
作者：
Wurzer, WJ;Obojes, K;Vlasak, R
第2组冠状病毒在巢病毒目内的特征在于独特的基因组组织。第2组冠状病毒的一个特征是存在编码血凝素酯酶（HE）蛋白的基因，而第1组和第3组冠状病毒中不存在这种基因。第2组中至少有三种冠状病毒株表达具有唾液酸-4-O-乙酰酯酶活性的结构蛋白，将它们与第2组的其他成员区分开来，第2组的其他成员编码对5-N-乙酰基-9-O-乙酰基神经氨酸特异的酶。小鼠肝炎病毒（MHV）S株和JHM株以及海雀病毒（PV）的酯酶特异性水解5-N-乙酰基-4-O-乙酰基神经氨酸（Neu 4，5Ac（2））以及合成底物乙酸对硝基苯酯、乙酸4-甲基伞形酮酯和荧光素二乙酸酯。MHV样酯酶对后者底物的K值比C型流感病毒的唾液酸-9-O-乙酰酯酶的K值低2 - 10倍。另一种非特异性酯酶底物，α-醋酸萘酯，用于原位检测的二聚体HE蛋白在SDS-聚丙烯酰胺凝胶。MHV-S、MHV-JHM和PV与含有Neu 4，5Ac的马血清糖蛋白结合（2）。通过碱处理或与病毒酯酶孵育使糖蛋白脱O-乙酰化导致完全丧失识别，表明MHV样冠状病毒与Neu 4，5Ac的特异性相互作用（2）。结合组2冠状病毒的不同系统发育谱系的证据，建议细分为亚组2a（MHV样病毒）和2b（牛冠状病毒样病毒）。
Group 2 coronaviruses are characterized within the order Nidovirales by a unique genome organization. A characteristic feature of group 2 coronaviruses is the presence of a gene encoding the haemagglutinin-esterase (HE) protein, which is absent in coronaviruses of groups 1 and 3. At least three coronavirus strains within group 2 expressed a structural protein with sialate-4-O-acetylesterase activity, distinguishing them from other members of group 2, which encode an enzyme specific for 5-N-acetyl-9-O-acetyl neuraminic acid. The esterases of mouse hepatitis virus (MHV) strains S and JHM and puffinosis virus (PV) specifically hydrolysed 5-N-acetyl-4-O-acetylneuraminic acid (Neu4,5Ac(2)) as well as the synthetic substrates p-nitrophenyl acetate, 4-methylumbelliferyl acetate and fluorescein diacetate. The K values of the MHV-like esterases for the latter substrates were two- to tenfold lower than those of the sialate-9-O-acetylesterases of influenza C viruses. Another unspecific esterase substrate, alpha-naphthyl acetate, was used for the in situ detection of the dimeric HE proteins in SDS-polyacrylamide gels. MHV-S, MHV-JHM and PV bound to horse serum glycoproteins containing Neu4,5Ac(2). De-O-acetylation of the glycoproteins by alkaline treatment or incubation with the viral esterases resulted in a complete loss of recognition, indicating a specific interaction of MHV-like coronaviruses with Neu4,5Ac(2). Combined with evidence for distinct phylogenetic lineages of group 2 coronaviruses, subdivision into subgroups 2a (MHV-like viruses) and 2b (bovine coronavirus-like viruses) is suggested.