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PDBsum entry 4zmd
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Protein binding
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PDB id
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4zmd
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References listed in PDB file
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Key reference
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Title
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Suppression of conformational heterogeneity at a protein-Protein interface.
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Authors
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L.N.Deis,
Q.Wu,
Y.Wang,
Y.Qi,
K.G.Daniels,
P.Zhou,
T.G.Oas.
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Ref.
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Proc Natl Acad Sci U S A, 2015,
112,
9028-9033.
[DOI no: ]
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PubMed id
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Abstract
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Staphylococcal protein A (SpA) is an important virulence factor from
Staphylococcus aureus responsible for the bacterium's evasion of the host immune
system. SpA includes five small three-helix-bundle domains that can each bind
with high affinity to many host proteins such as antibodies. The interaction
between a SpA domain and the Fc fragment of IgG was partially elucidated
previously in the crystal structure 1FC2. Although informative, the previous
structure was not properly folded and left many substantial questions
unanswered, such as a detailed description of the tertiary structure of SpA
domains in complex with Fc and the structural changes that take place upon
binding. Here we report the 2.3-Å structure of a fully folded SpA domain in
complex with Fc. Our structure indicates that there are extensive structural
rearrangements necessary for binding Fc, including a general reduction in SpA
conformational heterogeneity, freezing out of polyrotameric interfacial
residues, and displacement of a SpA side chain by an Fc side chain in a
molecular-recognition pocket. Such a loss of conformational heterogeneity upon
formation of the protein-protein interface may occur when SpA binds its multiple
binding partners. Suppression of conformational heterogeneity may be an
important structural paradigm in functionally plastic proteins.
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