Mechanisms of membrane protein crystallization in 'bicelles'

Despite remarkable progress, mainly due to the development of LCP and 'bicelle' crystallization, lack of structural information remains a bottleneck in membrane protein (MP) research. A major reason is the absence of complete understanding of the mechanism of crystallization. Here we present small-angle scattering studies of the evolution of the bicelle crystallization matrix in the course of MP crystal growth. Initially, the matrix corresponds to liquid-like bicelle state. However, after adding the precipitant, the crystallization matrix transforms to jelly-like state. The data suggest that this final phase is composed of interconnected ribbon-like bilayers, where crystals grow. A small amount of multilamellar phase appears, and its volume increases concomitantly with the volume of growing crystals. We suggest that the lamellar phase surrounds the crystals and is critical for crystal growth, which is also common for LCP crystallization. The study discloses mechanisms of bicelle MP crystallization and will support rational design of crystallization.

Automated summary

Despite remarkable progress in LCP and 'bicelle' crystallization, the lack of structural information remains a bottleneck in membrane protein research. This study uses small-angle scattering to investigate the evolution of the bicelle crystallization matrix during MP crystal growth and reveals the mechanisms of bicelle MP crystallization, providing support for rational design of crystallization.