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Title: Evidence for small-molecule-mediated loop stabilization in the structure of the isolated Pin1 WW domain

Two structures of a small protein with a defined tertiary fold, the isolated Pin1 WW domain, have been determined via racemic crystallization with small-molecule additives. These additives, which are either racemic or achiral, appear to stabilize a dynamic loop region of the structure. The human Pin1 WW domain is a small autonomously folding protein that has been useful as a model system for biophysical studies of β-sheet folding. This domain has resisted previous attempts at crystallization for X-ray diffraction studies, perhaps because of intrinsic conformational flexibility that interferes with the formation of a crystal lattice. Here, the crystal structure of the human Pin1 WW domain has been obtained via racemic crystallization in the presence of small-molecule additives. Both enantiomers of a 36-residue variant of the Pin1 WW domain were synthesized chemically, and the l- and d-polypeptides were combined to afford diffracting crystals. The structural data revealed packing interactions of small carboxylic acids, either achiral citrate or a d,l mixture of malic acid, with a mobile loop region of the WW-domain fold. These interactions with solution additives may explain our success in crystallization of this protein racemate. Molecular-dynamics simulations starting from the structure of the Pin1 WW domain suggest that themore » crystal structure closely resembles the conformation of this domain in solution. The structural data presented here should provide a basis for further studies of this important model system.« less
Authors:
; ; ; ;  [1]
  1. University of Wisconsin-Madison, Madison, WI 53706 (United States)
Publication Date:
OSTI Identifier:
22351300
Resource Type:
Journal Article
Resource Relation:
Journal Name: Acta Crystallographica. Section D: Biological Crystallography; Journal Volume: 69; Journal Issue: Pt 12; Other Information: PMCID: PMC3852655; PMID: 24311591; PUBLISHER-ID: bw5418; OAI: oai:pubmedcentral.nih.gov:3852655; Copyright (c) International Union of Crystallography 2013; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
Denmark
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CITRATES; CRYSTAL LATTICES; CRYSTALLIZATION; CRYSTALS; FLEXIBILITY; INTERACTIONS; MATHEMATICAL SOLUTIONS; MOLECULES; SHEETS; SIMULATION; SOLUTIONS; STABILIZATION; STOWING; X-RAY DIFFRACTION