Highly Branched Pentasaccharide-Bearing Amphiphiles for Membrane Protein Studies

Abstract

Detergents are essential tools for membrane protein manipulation. Micelles formed by detergent molecules have the ability to encapsulate the hydrophobic domains of membrane proteins. The resulting protein-detergent complexes (PDCs) are compatible with the polar environments of aqueous media, making structural and functional analysis feasible. Although a number of novel agents have been developed to overcome the limitations of conventional detergents, most of them have traditional head groups such as glucoside or maltoside. In this study, we introduce a class of amphiphiles, the PSA’Es with a novel highly branched penta-saccharide hydrophilic group. The PSA’Es conferred markedly increased stability to a diverse range of membrane proteins compared to conventional detergents, indicating a positive role for the new hydrophilic group in maintaining the native protein integrity. In addition, PDCs formed by PSA’Es were smaller and more suitable for electron microscopic analysis than those formed by DDM, indicating that the new agents have significant potential for the structure-function studies of membrane proteins.

Overcoming bottlenecks in the membrane protein structural biology pipeline

“…It is interesting to note that both the GNG/MNGs and Calixarenes contain larger, more structured head groups than conventional detergents, and this may be a key factor in their stabilising properties. In fact a recently published study using an even larger branched pentameric sugar based headgroup reports even greater stabilising properties, but this has not yet been used for structural studies [48].…”

New penta-saccharide-bearing tripod amphiphiles for membrane protein structure studies

“…Examples of these novel amphiphiles include tripod amphiphiles (TPAs), 19 facial amphiphiles (FAs), 20 neopentyl glycol (NG) amphiphiles (GNGs/MNGs/NDTs), 21 xylene- or mesitylene-based amphipiles (XMAs/MGAs), 22 mannitol-based amphiphiles (MNAs), 23 and penta-saccharide amphiphiles (PSEs). 24 Among these agents, the NG class agents (MNG-3 and GNG-3) have contributed to the crystal structure determinations of more than 30 new membrane proteins in the last six years, including several GPCRs. 25 Despite the development of dozens of novel agents, progress in membrane protein structural study remains slow.…”

Resorcinarene‐Based Facial Glycosides: Implication of Detergent Flexibility on Membrane‐Protein Stability

“…Recent representative classes include tripod amphiphiles, [2, 3] lipopeptide detergents, [4] hemifluorinated surfactants, [5] glucose or maltose neopentyl glycols (GNGs or MNGs), [6] glyco-diosgenin, [7] facial amphiphiles, [8] neopentyl glycol-derived triglucosides [9] and penta-saccharide-based amphiphiles. [10] Apart from these small amphiphiles, there are polymeric nano-assemblies (polymeric materials or polymer–lipid superassemblies) such as amphipols, [5, 11] nanodiscs [5, 12] and nanolipodisc particles. [13] In terms of membrane-protein stabilisation, most of these new agents were shown to be superior to DDM, the most widely used conventional detergent.…”

“…Over the subsequent additional incubation period, receptor activity gradually decreased over time, but the final receptor activity ( t = 2 days) observed for this new agent was even higher than the initial receptor activity ( t = 0 h) detected for DDM. It is notable that receptor ligand-binding activity observed at t = 4 h was the highest reported to date, [10, 24] indicating that RGA-C13 has an optimal architecture for receptor stability. The initial increase in receptor activity following the 4 h incubation observed for RGA-C11 and RGA-C13 could be the result of the slow rate of detergent exchange following dilution.…”

“…The large difference in the size of receptor–detergent complexes between RGA-C11/C13 and DDM observed here is unprecedented. [10, 24] …”