N-terminal mutants of herpes simplex virus type 2 gH are transported without gL but require gL for function
N-terminal mutants of herpes simplex virus type 2 gH are transported without gL but require gL for function
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DOI：
10.1128/jvi.00097-07
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发表时间：
2007-05-01
影响因子：
5.4
通讯作者：
Eisenberg, Roselyn J.
中科院分区：
文献类型：
--
作者：
Cairns, Tina M.;Friedman, Lisa S.;Eisenberg, Roselyn J.
糖蛋白H(Gh)在所有疱疹病毒中都是保守的，与g1、gB和大多数甲型疱疹病毒中的gD一样，对于病毒进入和细胞融合是必不可少的。在Gh/Gl异源二聚体中，Gh起融合作用，Gl作为Gh折叠和转运的伴侣。在这里，我们发现GH2的N端包含了参与其折叠和运输的重要元件。我们的结论是基于一系列Gh缺失突变体的表型，在这些突变体中，信号序列(残基1到18)被保留，N末端残基被移除到指定的数量。第一个突变体GH2 Delta 29(缺失19到28个残基)，与野生型(WT)Gh一样，需要gl来运输和发挥功能。令我们惊讶的是，另外两个突变体(GH2 Delta和GH2 Delta 72)被运输到细胞表面，但不依赖于gl，但即使与gl复合也是无功能的。重要的是，第四个突变体(GH2 Delta 48)是独立于gl运输的，但只有在与gl复合时才具有功能。利用一组抗GH2的单抗，我们发现当GH2 Delta 48单独表达时，其抗原结构与GH2 Delta 48/g1或GH2-WT/gl不同。GH2残基R39、Y41、W42或D44的突变允许Gh不依赖于gl转运。我们的结果还表明，Gl不仅是Gh转运所必需的，而且对于该复合体的折叠和功能也是必需的。由于Gh2 Delta/g1和Gh2 Delta 72/g1是无功能的，我们假设对Gh/gl功能至关重要的残基存在于该缺失区域内。进一步的突变鉴定表明L66和L72对功能是重要的。总之，我们的结果突出了几个关键的Gh残基：R39、Y41、W42和D44用于Gh运输，L66和L72用于Gh/gl结构和功能。
Glycoprotein H (gH) is conserved among all herpesviruses and is essential for virus entry and cell fusion along with gL, gB, and, in most alphaherpesviruses, gD. Within the gH/gL heterodimer, it is thought that gH accounts for the fusion function and gL acts as a chaperone for the folding and transport of gH. Here, we found that the N terminus of gH2 contains important elements involved in both its folding and its transport. Our conclusions are based on the phenotypes of a series of gH deletion mutants in which the signal sequence (residues 1 to 18) was retained and N-terminal residues were removed up to the number indicated. The first mutant, gH2 Delta 29 (deletion of residues 19 to 28), like wild-type (WT) gH, required gL for both transport and function. To our surprise, two other mutants (gH2 Delta 64 and gH2 Delta 72) were transported to the cell surface independent of gL but were nonfunctional, even when complexed with gL. Importantly, a fourth mutant (gH2 Delta 48) was transported independent of gL but was functional only when complexed with gL. Using a panel of monoclonal antibodies against gH2, we found that when gH2 Delta 48 was expressed alone, its antigenic structure differed from that of gH2 Delta 48/gL or gH2-WT/gL. Mutation of gH2 residue R39, Y41, W42, or D44 allowed gL-independent transport of gH. Our results also show that gL is not merely required for gH transport but is also necessary for the folding and function of the complex. Since gH2 Delta 64/gL and gH2 Delta 72/gL were nonfunctional, we hypothesized that residues critical for gH/gL function lie within this deleted region. Additional mutagenesis identified L66 and L72 as important for function. Together, our results highlight several key gH residues: R39, Y41, W42, and D44 for gH transport and L66 and L72 for gH/gL structure and function.