title: Detergent-mediated protein aggregation.
abstract: Because detergents are commonly used to solvate membrane proteins for structural evaluation, much attention has been devoted to assessing the conformational bias imparted by detergent micelles in comparison to the native environment of the lipid bilayer. Here, we conduct six 500-ns simulations of a system with >600,000 atoms to investigate the spontaneous self assembly of dodecylphosphocholine detergent around multiple molecules of the integral membrane protein PagP. This detergent formed equatorial micelles in which acyl chains surround the protein's hydrophobic belt, confirming existing models of the detergent solvation of membrane proteins. In addition, unexpectedly, the extracellular and periplasmic apical surfaces of PagP interacted with the headgroups of detergents in other micelles 85 and 60% of the time, respectively, forming complexes that were stable for hundreds of nanoseconds. In some cases, an apical surface of one molecule of PagP interacted with an equatorial micelle surrounding another molecule of PagP. In other cases, the apical surfaces of two molecules of PagP simultaneously bound a neat detergent micelle. In these ways, detergents mediated the non-specific aggregation of folded PagP. These simulation results are consistent with dynamic light scattering experiments, which show that, at detergent concentrations ≥600 mM, PagP induces the formation of large scattering species that are likely to contain many copies of the PagP protein. Together, these simulation and experimental results point to a potentially generic mechanism of detergent-mediated protein aggregation.
authors: Molecular Structure and Function, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada.
authors: Chris
authors: C
authors: Neale
authors: Hamed
authors: H
authors: Ghanei
authors: John
authors: J
authors: Holyoake
authors: Russell E
authors: RE
authors: Bishop
authors: Gilbert G
authors: GG
authors: Privé
authors: Régis
authors: R
authors: Pomès
mesh_terms: D003902:Detergents / Q000494:pharmacology*; D057927:Hydrophobic and Hydrophilic Interactions; D008565:Membrane Proteins / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D011489:Protein Denaturation / Q000187:drug effects; D055503:Protein Multimerization / Q000187:drug effects*; D055550:Protein Stability / Q000187:drug effects; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D014867:Water / Q000494:pharmacology
chemical_list: D003902:Detergents; D008565:Membrane Proteins; D014867:Water