Sidechain interactions in parallel β sheets: the energetics of cross-strand pairings


Abstract

Background: Both backbone hydrogen bonding and interactions between sidechains stabilize β sheets. Cross-strand interactions are the closest contacts between the sidechains of a β sheet. Here we investigate the energetics of cross-strand interactions using a variant of the B1 domain of immunoglobulin G (IgG) binding protein G (β1) as our model system. Results: Pairwise mutations of polar and nonpolar residues were made at a solvent-exposed site between the two central parallel β strands of β1. Both stabilizing and destabilizing interactions were measured. The greatest stabilizations were observed for charge–charge interactions. Our experimental study of sidechain interactions correlates with statistical preferences: residue pairs for which we measure stabilizing interaction energies occur together frequently, whereas destabilizing pairs are rarely observed together. Conclusions: Sidechain interactions modulate the stability of β sheets. We propose that cross-strand sidechain interactions specify correct strand register and ordering through the energetic benefit of optimally arranged pairings.

Submission Details

ID: sQRJcD7c3

Submitter: Marie Ary

Submission Date: Feb. 22, 2017, 5:33 p.m.

Version: 1

Publication Details
Merkel JS;Sturtevant JM;Regan L,Structure (1999) Sidechain interactions in parallel beta sheets: the energetics of cross-strand pairings. PMID:10574793
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