Schuy W, Will C, Kuroda K, Scholtissek C, Garten W, Klenk H D
EMBO J. 1986 Nov;5(11):2831-6. doi: 10.1002/j.1460-2075.1986.tb04576.x.
Mutants ts1 and ts227 of fowl plague virus have a temperature-sensitive defect in the transport of the hemagglutinin from the rough endoplasmic reticulum to the Golgi apparatus. The primary structure of the hemagglutinin of the mutants and of a number of revertants derived from them has been analysed by nucleotide sequencing. The transport block of the hemagglutinin of ts227 can be attributed to a single amino acid exchange. It involves the replacement of aspartic acid at position 457 by asparagine thereby introducing a new glycosylation site which appears to be located in a cryptic position in the lower part of the hemagglutinin stalk. Attachment of carbohydrate to this site is temperature-dependent. At permissive temperature only a small fraction of the monomers (approximately 30%) is glycosylated in this position, whereas at nonpermissive temperature this is the case with all subunits. The data suggest that under the latter conditions the new oligosaccharide interferes by steric hindrance with the trimerization of the hemagglutinin. The hemagglutinin of ts1 has an essential amino acid exchange at position 275 where serine is replaced by glycine. This substitution may increase the flexibility of the molecule in the hinge region between the globular domain and the stalk. The exchange of a conserved glutamic acid residue at position 398 that is involved in the interaction between different monomers contributes also to the structural instability of the ts1 hemagglutinin. These observations support the notion that the transport of the hemagglutinin from the rough endoplasmic reticulum to the Golgi apparatus depends on trimer assembly.
禽痘病毒的ts1和ts227突变体在血凝素从粗面内质网运输到高尔基体的过程中存在温度敏感缺陷。通过核苷酸测序分析了突变体及其衍生的一些回复株血凝素的一级结构。ts227血凝素的运输阻断可归因于单个氨基酸的交换。它涉及457位的天冬氨酸被天冬酰胺取代，从而引入了一个新的糖基化位点，该位点似乎位于血凝素柄下部的一个隐蔽位置。碳水化合物与该位点的连接是温度依赖性的。在允许温度下，只有一小部分单体（约30%）在此位置被糖基化，而在非允许温度下，所有亚基均如此。数据表明，在后一种情况下，新的寡糖通过空间位阻干扰血凝素的三聚化。ts1的血凝素在275位有一个必需的氨基酸交换，丝氨酸被甘氨酸取代。这种取代可能增加分子在球状结构域和柄之间的铰链区的柔韧性。参与不同单体间相互作用的398位保守谷氨酸残基的交换也导致ts1血凝素的结构不稳定。这些观察结果支持了血凝素从粗面内质网运输到高尔基体取决于三聚体组装的观点。
