On the Mechanism of Membrane Protein Crystallization in Lipidic Mesophases

Abstract

The in meso method for crystallizing membrane proteins has been shown to work with a range of different protein types. The method involves reconstituting the target protein into the bilayer of a bicontinuous lipid mesophase followed by an induced phase separation brought on by the addition of a precipitant. A mechanism has been proposed for how in meso crystallogenesis comes about at a molecular level. However, aspects of the hypothesis are not fully developed. These are examined and expanded on here by considering the behavior of related but simpler systems and processes where the mode of action is understood and founded in experiment. By building up from this series of model, well behaved systems a more complete view of what takes place during the in meso crystallogenesis of membrane proteins is obtained. In addition to the underlying theory, some of the more practical aspects of the method are explored and their basis in the hypothesis is established. This treatment suggests a host of experiments to further test and develop the hypothesis. By deciphering the underlying molecular mechanism, clearer insights emerge for practicing a rational approach to membrane protein crystallogenesis.