PDF(Pubmed)
Abstract：
The multibasic furin cleavage site at the S1/S2 boundary of the spike protein is a hallmark of SARS-CoV-2 and plays a crucial role in viral infection. However, the mechanism underlying furin activation and its regulation remain poorly understood. Here, we show that GalNAc-T3 and T7 jointly initiate clustered O-glycosylations in the furin cleavage site of the SARS-CoV-2 spike protein, which inhibit furin processing, suppress the incorporation of the spike protein into virus-like-particles and affect viral infection. Mechanistic analysis reveals that the assembly of the spike protein into virus-like particles relies on interactions between the furin-cleaved spike protein and the membrane protein of SARS-CoV-2, suggesting a possible mechanism for furin activation. Interestingly, mutations in the spike protein of the alpha and delta variants of the virus confer resistance against glycosylation by GalNAc-T3 and T7. In the omicron variant, additional mutations reverse this resistance, making the spike protein susceptible to glycosylation in vitro and sensitive to GalNAc-T3 and T7 expression in human lung cells. Our findings highlight the role of glycosylation as a defense mechanism employed by host cells against SARS-CoV-2 and shed light on the evolutionary interplay between the host and the virus.
摘要：
刺突蛋白S1/S2边界的多碱性弗林蛋白酶裂解位点是SARS-CoV-2的标志，在病毒感染中起着至关重要的作用。然而,弗林蛋白酶激活及其调节的潜在机制仍然知之甚少。这里,我们显示GalNAc-T3和T7共同启动SARS-CoV-2刺突蛋白的弗林蛋白酶裂解位点的成簇O-糖基化，抑制弗林蛋白酶加工，抑制刺突蛋白掺入病毒样颗粒并影响病毒感染。机理分析表明，刺突蛋白组装成病毒样颗粒依赖于弗林蛋白酶切割的刺突蛋白与SARS-CoV-2的膜蛋白之间的相互作用，这表明弗林蛋白酶激活的可能机制。有趣的是,病毒α和δ变体的刺突蛋白中的突变赋予对GalNAc-T3和T7糖基化的抗性。在omicron变体中，额外的突变逆转了这种抗性，使得刺突蛋白在体外对糖基化敏感，对人肺细胞中的GalNAc-T3和T7表达敏感。我们的发现强调了糖基化作为宿主细胞针对SARS-CoV-2的防御机制的作用，并阐明了宿主与病毒之间的进化相互作用。
