Format

Send to

Choose Destination
Biochim Biophys Acta. 2013 Nov;1828(11):2592-608. doi: 10.1016/j.bbamem.2013.06.023. Epub 2013 Jun 27.

Structural adaptations of proteins to different biological membranes.

Author information

1
College of Pharmacy, Department of Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109-1065, USA. Electronic address: irinap@umich.edu.

Abstract

To gain insight into adaptations of proteins to their membranes, intrinsic hydrophobic thicknesses, distributions of different chemical groups and profiles of hydrogen-bonding capacities (α and β) and the dipolarity/polarizability parameter (π*) were calculated for lipid-facing surfaces of 460 integral α-helical, β-barrel and peripheral proteins from eight types of biomembranes. For comparison, polarity profiles were also calculated for ten artificial lipid bilayers that have been previously studied by neutron and X-ray scattering. Estimated hydrophobic thicknesses are 30-31Å for proteins from endoplasmic reticulum, thylakoid, and various bacterial plasma membranes, but differ for proteins from outer bacterial, inner mitochondrial and eukaryotic plasma membranes (23.9, 28.6 and 33.5Å, respectively). Protein and lipid polarity parameters abruptly change in the lipid carbonyl zone that matches the calculated hydrophobic boundaries. Maxima of positively charged protein groups correspond to the location of lipid phosphates at 20-22Å distances from the membrane center. Locations of Tyr atoms coincide with hydrophobic boundaries, while distributions maxima of Trp rings are shifted by 3-4Å toward the membrane center. Distributions of Trp atoms indicate the presence of two 5-8Å-wide midpolar regions with intermediate π* values within the hydrocarbon core, whose size and symmetry depend on the lipid composition of membrane leaflets. Midpolar regions are especially asymmetric in outer bacterial membranes and cell membranes of mesophilic but not hyperthermophilic archaebacteria, indicating the larger width of the central nonpolar region in the later case. In artificial lipid bilayers, midpolar regions are observed up to the level of acyl chain double bonds.

KEYWORDS:

Hydrophobic thickness; Hyperthermophile; Lipid bilayer; Membrane asymmetry; Membrane protein; Polarity profile

PMID:
23811361
PMCID:
PMC3787962
DOI:
10.1016/j.bbamem.2013.06.023
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center