Differential utilization of a conserved motif for the proteolytic maturation of vaccinia virus proteins.
Differential utilization of a conserved motif for the proteolytic maturation of vaccinia virus proteins.
复制标题
痘苗病毒蛋白蛋白水解成熟中保守基序的差异利用。
DOI：
10.1006/viro.1994.1174
复制
发表时间：
1994
期刊：
影响因子：
3.7
通讯作者：
Hruby,DE
中科院分区：
文献类型：
--
作者：
Whitehead,SS;Hruby,DE
一些牛痘病毒核心蛋白被合成为大的前体蛋白，随后在病毒成熟过程中被加工成较小的产物。这些蛋白的氨基酸比对显示，在它们确定的切割位点有一个保守的Ala-Gly-X基序（AG*X）。为了更好地了解卵裂位点选择的调控，我们在整个牛痘病毒基因组序列中搜索该AG*X基序在预测的开放阅读框中的出现。在发现的82个位点中，有19个类似于先前被证明活跃加工的裂解位点，即P25K和P4b的AG*A，以及P4a的AG*S和AG*T。为了测试AG*X基序利用的普遍性，已经使用免疫学方法与n端微测序程序相一致来确定含有AG*A位点的预测蛋白的哪个子集在体内被利用。在7个含AG* a的底物中，4个被切割，3个不被切割。考虑到所有已知的AG*X加工事件，似乎只有那些在感染后期表达并与组装病毒粒子相关的蛋白质才是蛋白水解裂解的候选底物。这些蛋白包括P4a， P4b, P25K，以及新发现的P21K和P17K（分别来源于基因A17L和A12L）。尽管诸如DNA聚合酶、P37K和宿主范围蛋白等蛋白质含有一致的切割位点，但它们被排除在加工之外。这种蛋白水解排除可能是因为这些蛋白不符合上述两个标准，这表明组装病毒粒子中的时间表达或区隔化（底物呈递）可能在蛋白水解中起调节作用。
Several of the vaccinia virus core proteins are synthesized as large precursor proteins which are subsequently processed to smaller products during the course of viral maturation. Amino acid alignment of these proteins reveals a conserved Ala-Gly-X motif (AG*X) at their confirmed cleavage sites. To better understand the regulation of cleavage site selection, the sequence of the entire vaccinia virus genome was searched for the occurrence of this AG*X motif in predicted open reading frames. Of the 82 sites found, 19 resembled cleavage sites which have previously been shown to be actively processed, namely AG*A of P25K and P4b, and AG*S and AG*T of P4a. To test the universality of the AG*X motif utilization, immunological methods in concert with N-terminal microsequencing procedures have been used to determine which of the subset of predicted proteins containing AG*A sites are utilizedin vivo.Of the seven AG*A-containing substrates, four were cleaved and three were not. Considering all the known AG*X processing events, it appears that only those proteins expressed at late times during infection and associated with the assembling virion are candidate substrates for proteolytic cleavage. Such proteins include P4a, P4b, P25K, and the newly identified P21K and P17K (derived from genes A17L and A12L, respectively). Although proteins such as DNA polymerase, P37K, and a host range protein contain a consensus cleavage site, they are excluded from processing. This proteolytic exclusion presumably occurs because these proteins do not meet both of the above criteria, which suggests that temporal expression or compartmentalization (substrate presentation) in the assembling virion may play a regulatory role in proteolysis.