Modular detergents tailor the purification and structural analysis of membrane proteins including G-protein coupled receptors

Abstract

Detergents enable the purification of membrane proteins and are indispensable reagents in structural biology. Even though a large variety of detergents have been developed in the last century, the challenge remains to identify guidelines that allow fine-tuning of detergents for individual applications in membrane protein research. Addressing this challenge, here we introduce the family of oligoglycerol detergents (OGDs). Native mass spectrometry (MS) reveals that the modular OGD architecture offers the ability to control protein purification and to preserve interactions with native membrane lipids during purification. In addition to a broad range of bacterial membrane proteins, OGDs also enable the purification and analysis of a functional G-protein coupled receptor (GPCR). Moreover, given the modular design of these detergents, we anticipate fine-tuning of their properties for specific applications in structural biology. Seen from a broader perspective, this represents a significant advance for the investigation of membrane proteins and their interactions with lipids.

Structure and Dynamics of GPCRs in Lipid Membranes: Physical Principles and Experimental Approaches

“…Generally, there is no one detergent appropriate for all receptors, requiring screening to find a suitable candidate. Indeed, taking a modular approach a recent publication demonstrated that varying tail and head groups can greatly affect the functionality and lipid retention of preparations of NTR1 [ 180 ]. Within the family of alkyl glucosides, it seems that varieties with branched alky chains, in particular LMNG, increase the stability of isolated receptors [ 181 , 182 ].…”

A new azobenzene-based design strategy for detergents in membrane protein research

“…The basicity of detergents has recently been identied as a key parameter for controlling charge reduction in membrane protein mass spectrometry. 7,59 This prompted an important question. Can azobenzene detergents be used for controlling protein charge reduction by light?…”

“…60 Detergents are in many ways important for the native MS analysis of membrane proteins as they can protect the native structure in solution and during the nESI process. 6,8,59 The detergent concentration used for solubilising membrane proteins is oen adjusted to a multiple of the detergents' critical aggregation concentration (cac). 8 Attempts to solubilise AmtB with concentrations below the cac of trans 6 led to protein precipitation, thus underlining that at least concentrations close to the cac are needed to stabilize AmtB in aqueous buffer.…”

Changes in Membrane Protein Structural Biology

“…Control of detergent concentration is also vital as too much detergent can prevent crystallisation and promotes detergent phase separation and detergent crystals. In some cases, a suitable mixture of detergents must be used to alter the protein-detergent complex instead of a single detergent which is sufficient in most cases [188].…”