Approaches toab initiomolecular replacement of α-helical transmembrane proteins

Abstract

α-Helical transmembrane proteins are a ubiquitous and important class of proteins, but present difficulties for crystallographic structure solution. Here, the effectiveness of theAMPLEmolecular replacement pipeline in solving α-helical transmembrane-protein structures is assessed using a small library of eight ideal helices, as well as search models derived fromab initiomodels generated both with and without evolutionary contact information. The ideal helices prove to be surprisingly effective at solving higher resolution structures, butab initio-derived search models are able to solve structures that could not be solved with the ideal helices. The addition of evolutionary contact information results in a marked improvement in the modelling and makes additional solutions possible.