Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA.
Protein and Crystallography Facility, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
Commun Biol. 2022 Feb 8;5(1):115. doi: 10.1038/s42003-022-03063-y.
β-Coronaviruses such as SARS-CoV-2 hijack coatomer protein-I (COPI) for spike protein retrograde trafficking to the progeny assembly site in endoplasmic reticulum-Golgi intermediate compartment (ERGIC). However, limited residue-level details are available into how the spike interacts with COPI. Here we identify an extended COPI binding motif in the spike that encompasses the canonical K-x-H dibasic sequence. This motif demonstrates selectivity for αCOPI subunit. Guided by an in silico analysis of dibasic motifs in the human proteome, we employ mutagenesis and binding assays to show that the spike motif terminal residues are critical modulators of complex dissociation, which is essential for spike release in ERGIC. αCOPI residues critical for spike motif binding are elucidated by mutagenesis and crystallography and found to be conserved in the zoonotic reservoirs, bats, pangolins, camels, and in humans. Collectively, our investigation on the spike motif identifies key COPI binding determinants with implications for retrograde trafficking.
β 冠状病毒（如 SARS-CoV-2）劫持衣壳蛋白 I（COPI）用于棘突蛋白逆行转运到内质网-高尔基体中间池（ERGIC）中的子代组装位点。然而，关于棘突与 COPI 相互作用的细节有限。在这里，我们确定了棘突中包含经典 K-x-H 双碱性序列的扩展 COPI 结合基序。该基序显示对 αCOPI 亚基的选择性。受人类蛋白质组中二碱基基序的计算机分析的指导，我们通过突变和结合测定来显示棘突基序末端残基是复合物解离的关键调节剂，这对于 ERGIC 中的棘突释放是必不可少的。通过突变和晶体学阐明了对棘突基序结合至关重要的 αCOPI 残基，并且在人畜共患病宿主蝙蝠、穿山甲、骆驼和人类中发现这些残基是保守的。总的来说，我们对棘突基序的研究确定了关键的 COPI 结合决定因素，对逆行转运具有重要意义。
