PDBsum entry 4znc

Protein binding

PDB id: 4znc

Contents

Protein chains

53 a.a.

207 a.a.

195 a.a.

Waters ×126

PDB id:

4znc

Name:

Protein binding

Title:

Fc fragment of human igg in complex with thE C domain of staphylococcal protein a mutant - q9w

Structure:

Immunoglobulin g-binding protein a. Chain: a, b, c. Fragment: unp residues 270-327. Synonym: igg-binding protein a,staphylococcal protein a. Engineered: yes. Mutation: yes. Ig gamma-3 chain c region. Chain: d, e, f. Fragment: unp residues 168-377.

Source:

Staphylococcus aureus. Organism_taxid: 1280. Gene: spa. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008. Homo sapiens. Human. Organism_taxid: 9606. Gene: ighg3.

Resolution:

2.28Å R-factor: 0.198 R-free: 0.242

Authors:

L.N.Deis,T.G.Oas

Key ref:

L.N.Deis et al. (2015). Suppression of conformational heterogeneity at a protein-protein interface. Proc Natl Acad Sci U S A, 112, 9028-9033. PubMed id: 26157136 DOI: 10.1073/pnas.1424724112

Date:

04-May-15 Release date: 15-Jul-15

Protein chains

P38507  (SPA_STAAU) -  Immunoglobulin G-binding protein A from Staphylococcus aureus

Seq: 508 a.a.

Struc: 53 a.a.*

Protein chains

P01860  (IGHG3_HUMAN) -  Immunoglobulin heavy constant gamma 3 from Homo sapiens

Seq: 446 a.a.

Struc: 207 a.a.*

Protein chain

P01860  (IGHG3_HUMAN) -  Immunoglobulin heavy constant gamma 3 from Homo sapiens

Seq: 446 a.a.

Struc: 195 a.a.*

* PDB and UniProt seqs differ at 6 residue positions (black crosses)

DOI no: 10.1073/pnas.1424724112

Proc Natl Acad Sci U S A 112:9028-9033 (2015)

PubMed id: 26157136

Suppression of conformational heterogeneity at a protein-protein interface.

L.N.Deis, Q.Wu, Y.Wang, Y.Qi, K.G.Daniels, P.Zhou, T.G.Oas.

ABSTRACT

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.