Asunto(s)
COVID-19 , ADN Helicasas , ARN Helicasas , Proteínas con Motivos de Reconocimiento de ARN , SARS-CoV-2 , Replicación Viral , Humanos , Replicación Viral/fisiología , SARS-CoV-2/fisiología , COVID-19/metabolismo , COVID-19/virología , Proteínas con Motivos de Reconocimiento de ARN/metabolismo , Proteínas con Motivos de Reconocimiento de ARN/fisiología , ARN Helicasas/metabolismo , ARN Helicasas/fisiología , ADN Helicasas/metabolismo , ADN Helicasas/fisiología , Animales , Proteínas de Unión a Poli-ADP-RibosaRESUMEN
Abscission is the final stage of cytokinesis, which cleaves the intercellular bridge (ICB) connecting two daughter cells. Abscission requires tight control of the recruitment and polymerization of the Endosomal Protein Complex Required for Transport-III (ESCRT-III) components. We explore the role of post-translational modifications in regulating ESCRT dynamics. We discover that SMYD2 methylates the lysine 6 residue of human CHMP2B, a key ESCRT-III component, at the ICB, impacting the dynamic relocation of CHMP2B to sites of abscission. SMYD2 loss-of-function (genetically or pharmacologically) causes CHMP2B hypomethylation, delayed CHMP2B polymerization and delayed abscission. This is phenocopied by CHMP2B lysine 6 mutants that cannot be methylated. Conversely, SMYD2 gain-of-function causes CHMP2B hypermethylation and accelerated abscission, specifically in cells undergoing cytokinetic challenges, thereby bypassing the abscission checkpoint. Additional experiments highlight the importance of CHMP2B methylation beyond cytokinesis, namely during ESCRT-III-mediated HIV-1 budding. We propose that lysine methylation signaling fine-tunes the ESCRT-III machinery to regulate the timing of cytokinetic abscission and other ESCRT-III dependent functions.
Asunto(s)
Citocinesis , Complejos de Clasificación Endosomal Requeridos para el Transporte , N-Metiltransferasa de Histona-Lisina , Humanos , Complejos de Clasificación Endosomal Requeridos para el Transporte/metabolismo , Complejos de Clasificación Endosomal Requeridos para el Transporte/genética , Células HeLa , N-Metiltransferasa de Histona-Lisina/metabolismo , N-Metiltransferasa de Histona-Lisina/genética , VIH-1/metabolismo , VIH-1/genética , VIH-1/fisiología , Lisina/metabolismo , Metilación , Procesamiento Proteico-PostraduccionalRESUMEN
Considerable progress has been made in understanding the molecular host-virus battlefield during SARS-CoV-2 infection. Nevertheless, the assembly and egress of newly formed virions are less understood. To identify host proteins involved in viral morphogenesis, we characterize the proteome of SARS-CoV-2 virions produced from A549-ACE2 and Calu-3 cells, isolated via ultracentrifugation on sucrose cushion or by ACE-2 affinity capture. Bioinformatic analysis unveils 92 SARS-CoV-2 virion-associated host factors, providing a valuable resource to better understand the molecular environment of virion production. We reveal that G3BP1 and G3BP2 (G3BP1/2), two major stress granule nucleators, are embedded within virions and unexpectedly favor virion production. Furthermore, we show that G3BP1/2 participate in the formation of cytoplasmic membrane vesicles, that are likely virion assembly sites, consistent with a proviral role of G3BP1/2 in SARS-CoV-2 dissemination. Altogether, these findings provide new insights into host factors required for SARS-CoV-2 assembly with potential implications for future therapeutic targeting.
