The coxsackievirus 2B protein increases efflux of ions from the endoplasmic reticulum and Golgi, thereby inhibiting protein trafficking through the Golgi
The coxsackievirus 2B protein increases efflux of ions from the endoplasmic reticulum and Golgi, thereby inhibiting protein trafficking through the Golgi
复制标题
DOI：
10.1074/jbc.m511766200
复制
发表时间：
2006-05-19
影响因子：
4.8
通讯作者：
van Kuppeveld, Frank J.
中科院分区：
文献类型：
--
作者：
De Jong, Arjan S.;Visch, Henk-Jan;van Kuppeveld, Frank J.
柯萨奇病毒感染导致内质网 (ER) 和高尔基体 Ca2+ 储备的充盈状态迅速降低。柯萨奇病毒 2B 蛋白是一种小膜蛋白，定位于高尔基体，并在较小程度上定位于内质网，已被认为通过形成膜积分孔，从而增加 Ca2+ 从储备中的流出，在这种效应中发挥重要作用。这里提供的证据支持这一观点，并排除了 2B 减少钙储存中 Ca2+ 吸收的可能性。对透化细胞中细胞器内游离 Ca2+ 的测量表明，2B 降低储存的 Ca2+ 充盈状态的能力在稳定的 ATP 下得以保留。无细胞系统中的生化分析进一步表明，2B 对肌浆/内质网钙 ATP 酶（将 Ca2+ 从细胞质转运至储存库的 Ca2+-ATP 酶）的活性没有不利影响。为了研究 2B 是否特别影响 Ca2+ 稳态或其他离子梯度，我们测量了腔内高尔基体 pH 值。 2B 的表达导致高尔基体 pH 值升高，表明 H+ 从高尔基体腔流出。这些数据共同支持了这样一个模型：2B 通过形成膜积分孔来增加内质网和高尔基体的离子流出。我们已经证明，这种活性的一个主要结果是抑制通过高尔基复合体的蛋白质运输。
Coxsackievirus infection leads to a rapid reduction of the filling state of the endoplasmic reticulum ( ER) and Golgi Ca2+ stores. The coxsackievirus 2B protein, a small membrane protein that localizes to the Golgi and to a lesser extent to the ER, has been proposed to play an important role in this effect by forming membrane-integral pores, thereby increasing the efflux of Ca2+ from the stores. Here, evidence is presented that supports this idea and that excludes the possibility that 2B reduces the uptake of Ca2+ into the stores. Measurement of intra-organelle-free Ca2+ in permeabilized cells revealed that the ability of 2B to reduce the Ca2+ filling state of the stores was preserved at steady ATP. Biochemical analysis in a cell-free system further showed that 2B had no adverse effect on the activity of the sarco/endoplasmic reticulum calcium ATPase, the Ca2+-ATPase that transports Ca2+ from the cytosol into the stores. To investigate whether 2B specifically affects Ca2+ homeostasis or other ion gradients, we measured the lumenal Golgi pH. Expression of 2B resulted in an increased Golgi pH, indicative for the efflux of H+ from the Golgi lumen. Together, these data support a model that 2B increases the efflux of ions from the ER and Golgi by forming membrane-integral pores. We have demonstrated that a major consequence of this activity is the inhibition of protein trafficking through the Golgi complex.