Helix perturbations in membrane proteins assist in inter-helical interactions and optimal helix positioning in the bilayer.
Biochim Biophys Acta
; 1858(11): 2804-2817, 2016 Nov.
Article
in En
| MEDLINE
| ID: mdl-27521749
ABSTRACT
Transmembrane (TM) helices in integral membrane proteins are primarily α-helical in structure. Here we analyze 1134 TM helices in 90 high resolution membrane proteins and find that apart from the widely prevalent α-helices, TM regions also contain stretches of 310 (3 to 8 residues) and π-helices (5 to 19 residues) with distinct sequence signatures. The various helix perturbations in TM regions comprise of helices with kinked geometry, as well as those with an interspersed 310/π-helical fragment and show high occurrence in a few membrane proteins. Proline is frequently present at sites of these perturbations, but it is neither a necessary nor a sufficient requirement. Helix perturbations are also conserved within a family of membrane proteins despite low sequence identity in the perturbed region. Furthermore, a perturbation influences the geometry of the TM helix, mediates inter-helical interactions within and across protein chains and avoids hydrophobic mismatch of the helix termini with the bilayer. An analysis of π-helices in the TM regions of the heme copper oxidase superfamily shows that interspersed π-helices can vary in length from 6 to 19 amino acids or be entirely absent, depending upon the protein function. The results presented here would be helpful for prediction of 310 and π-helices in TM regions and can assist the computational design of membrane proteins.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Oxidoreductases
/
Proline
/
Hemeproteins
/
Lipid Bilayers
/
Membrane Proteins
Type of study:
Prognostic_studies
Language:
En
Journal:
Biochim Biophys Acta
Year:
2016
Document type:
Article
Affiliation country:
India