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Structures of single‐layer β‐sheet proteins evolved from β‐hairpin repeats
Author(s) -
Xu Qingping,
Biancalana Matthew,
Grant Joanna C.,
Chiu HsiuJu,
Jaroszewski Lukasz,
Knuth Mark W.,
Lesley Scott A.,
Godzik Adam,
Elsliger MarcAndré,
Deacon Ashley M.,
Wilson Ian A.
Publication year - 2019
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.3683
Subject(s) - beta sheet , folding (dsp implementation) , protein folding , hydrogen bond , protein structure , crystallography , chemistry , biology , biophysics , biochemistry , molecule , organic chemistry , electrical engineering , engineering
ABSTRACT Free‐standing single‐layer β‐sheets are extremely rare in naturally occurring proteins, even though β‐sheet motifs are ubiquitous. Here we report the crystal structures of three homologous, single‐layer, anti‐parallel β‐sheet proteins, comprised of three or four twisted β‐hairpin repeats. The structures reveal that, in addition to the hydrogen bond network characteristic of β‐sheets, additional hydrophobic interactions mediated by small clusters of residues adjacent to the turns likely play a significant role in the structural stability and compensate for the lack of a compact hydrophobic core. These structures enabled identification of a family of secreted proteins that are broadly distributed in bacteria from the human gut microbiome and are putatively involved in the metabolism of complex carbohydrates. A conserved surface patch, rich in solvent‐exposed tyrosine residues, was identified on the concave surface of the β‐sheet. These new modular single‐layer β‐sheet proteins may serve as a new model system for studying folding and design of β‐rich proteins.