Continuous flexibility analysis of SARS-CoV-2 spike prefusion structures
Roberto Melero, Carlos Óscar S. Sorzano, Brent Foster, José Luis Vilas, Marta Martínez, R. Marabini, Erney Ramírez-Aportela, Rubén Sánchez-García, David Herreros, Laura del Caño, Patricia Losana, Yunior César Fonseca-Reyna, Pablo Conesa, Daniel Wrapp, Pablo Chacón, Jason S. McLellan, Hemant D. Tagare, J.M. Carazo
Abstract
Using a new consensus-based image-processing approach together with principal component analysis, the flexibility and conformational dynamics of the SARS-CoV-2 spike in the prefusion state have been analysed. These studies revealed concerted motions involving the receptor-binding domain (RBD), N-terminal domain, and subdomains 1 and 2 around the previously characterized 1-RBD-up state, which have been modeled as elastic deformations. It is shown that in this data set there are not well defined, stable spike conformations, but virtually a continuum of states. An ensemble map was obtained with minimum bias, from which the extremes of the change along the direction of maximal variance were modeled by flexible fitting. The results provide a warning of the potential image-processing classification instability of these complicated data sets, which has a direct impact on the interpretability of the results.