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The Membrane- and Soluble-Protein Helix-Helix Interactome: Similar Geometry via Different Interactions

2015; Elsevier BV; Volume: 23; Issue: 3 Linguagem: Inglês

10.1016/j.str.2015.01.009

1878-4186

Shaoqing Zhang, Daniel W. Kulp, Chaim A. Schramm, Marco Mravic, Ilan Samish, William F. DeGrado,

Glycosylation and Glycoproteins Research

Summary α Helices are a basic unit of protein secondary structure and therefore the interaction between helices is crucial to understanding tertiary and higher-order folds. Comparing subtle variations in the structural and sequence motifs between membrane and soluble proteins sheds light on the different constraints faced by each environment and elucidates the complex puzzle of membrane protein folding. Here, we demonstrate that membrane and water-soluble helix pairs share a small number of similar folds with various interhelical distances. The composition of the residues that pack at the interface between corresponding motifs shows that hydrophobic residues tend to be more enriched in the water-soluble class of structures and small residues in the transmembrane class. The latter group facilitates packing via sidechain- and backbone-mediated hydrogen bonds within the low-dielectric membrane milieu. The helix-helix interactome space, with its associated sequence preferences and accompanying hydrogen-bonding patterns, should be useful for engineering, prediction, and design of protein structure.