EFFECTS OF EXPOSURE TO LOW PH ON THE LATERAL MOBILITY OF INFLUENZA HEMAGGLUTININ EXPRESSED AT THE CELL-SURFACE - CORRELATION BETWEEN MOBILITY INHIBITION AND INACTIVATION
EFFECTS OF EXPOSURE TO LOW PH ON THE LATERAL MOBILITY OF INFLUENZA HEMAGGLUTININ EXPRESSED AT THE CELL-SURFACE - CORRELATION BETWEEN MOBILITY INHIBITION AND INACTIVATION
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DOI：
10.1021/bi00052a014
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发表时间：
1993-01-12
期刊：
影响因子：
2.9
通讯作者：
HENIS, YI
中科院分区：
文献类型：
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作者：
GUTMAN, O;DANIELI, T;HENIS, YI
为了研究病毒糖蛋白迁移率在膜融合中的可能作用，采用荧光光漂白恢复来研究暴露于弱酸性pH（将许多病毒融合蛋白转化为融合活性形式所需）对转染细胞表面表达的流感血凝素（HA）蛋白的侧向迁移率的影响。比较来自两种不同菌株的HA蛋白：X：31 HA，其通过短暂暴露于pH 4.9而活化，但在较长的暴露时间下不可逆地失活，和来自A/Japan/305/57的HA，其在该pH下相对稳定地失活[Puri，A.，Booy，F. P.，多姆斯河W.，白色，J.M.，&布卢门塔尔，R. Virol. 64，3824-3832]。使用VS-40载体在CV-1细胞中表达的来自两种菌株的HA蛋白在细胞表面表现出相对不受限制的侧向扩散。在短暂暴露于pH 4.9（1 min）以介导转化为融合状态后，高迁移率持续存在。较长时间（长达15分钟）的预孵育在pH 4.9抑制X：31 HA的横向流动性（横向扩散速率显着降低，随后固定），但不是A/日本HA，其融合活性是耐这样的治疗。由于在低pH值下预孵育，X：31 HA的侧向移动性的抑制对CV-1细胞没有特异性，并且在稳定表达该蛋白的CHO细胞系中也发现了该抑制。所呈现的结果证明了迁移率的丧失和融合活性的失活之间的密切相关性，这与HA蛋白的横向运动是融合所需的概念雅阁。我们建议，X：31 HA在低pH值下长时间孵育后的失活涉及一种类型的增强聚集，导致固定。
To investigate the possible role of viral glycoprotein mobility in membrane fusion, fluorescence photobleaching recovery was employed to study the effects of exposure to mildly acidic pH (required to convert many viral fusion proteins to the fusion-active form) on the lateral mobility of influenza hemagglutinin (HA) proteins expressed at the surface of transfected cells. HA proteins from two different strains were compared: X:31 HA, which is activated by a brief exposure to pH 4.9 but is irreversibly inactivated at longer exposure times, and HA from A/Japan/305/57, which is relatively stable to inactivation at this pH [Puri, A., Booy, F. P., Doms, R. W., White, J. M., & Blumenthal, R. (1990) J. Virol. 64, 3824-3832]. The HA proteins from both strains, expressed in CV-1 cells using VS-40 vectors, exhibited relatively unrestricted lateral diffusion at the cell surface. The high mobility persisted following a brief exposure (1 min) to pH 4.9 to mediate conversion to the fusogenic state. Longer times (up to 15 min) of preincubation at pH 4.9 inhibited the lateral mobility of X:31 HA (the lateral diffusion rate was markedly reduced, followed by immobilization) but not of A/Japan HA, whose fusion activity is resistant to such treatment. Inhibition of the lateral mobility of X:31 HA due to preincubation at low pH was not specific to the CV-1 cells and was found also in a CHO cell line stably expressing this protein. The results presented demonstrate a close correlation between loss of mobility and inactivation of fusogenic activity, in accord with the notion that lateral motion of the HA proteins is required for fusion. We propose that the inactivation of X:31 HA following prolonged incubation at low pH involves a type of enhanced aggregation that leads to immobilization.