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Mapping the iκB kinase beta (ikkβ)-binding interface of B14, a vaccinia virus inhibitor of IKKβ-mediated activation of nuclear factor kappa B

DOI: 10.1074/jbc.M111.231381 DOI Help
PMID: 21474453 PMID Help

Authors: Camila Benfield (Imperial College London) , Daniel Mansur (Imperial College London) , Laura Mccoy (Imperial College London) , Brian Ferguson (Imperial College London) , Mohammad Bahar (University of Oxford) , Asa Oldring (University of Oxford) , Jonathan Grimes (Division of Structural Biology, University of Oxford) , Dave Stuart (Diamond Light Source) , Stephen Graham (University of Cambridge) , Geoffrey Smith (Imperial College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Structural Biology

State: Published (Approved)
Published: April 2011

Open Access Open Access

Abstract: The IκB kinase (IKK) complex regulates activation of nuclear factor kappa B (NF-κB), a critical transcription factor in mediating inflammatory and immune responses. Not surprisingly, therefore, many viruses seek to inhibit NF-κB activation. The vaccinia virus (VACV) B14 protein contributes to virus virulence by binding to the IKKβ subunit of the IKK complex and preventing NF-κB activation in response to pro-inflammatory stimuli. Previous crystallographic studies showed that the B14 protein has a Bcl-2-like fold and forms homo-dimers in the crystal. However, multi-angle light scattering indicated that B14 is in monomer:dimer equilibrium in solution. This transient self-association suggested that the hydrophobic dimerisation interface of B14 might also mediate its interaction with IKKβ and this was investigated by introducing amino acid substitutions on the dimer interface. One mutant (Y35E) was entirely monomeric but still co-immunoprecipitated with IKKβ and blocked both NF-κB nuclear translocation and NF-κB-dependent gene expression. Therefore, B14 homo-dimerisation is non-essential for binding and inhibition of IKKβ. In contrast, a second monomeric mutant (F130K) neither bound IKKβ nor inhibited NF-κB-dependent gene expression, demonstrating that this residue is required for the B14-IKKβ interaction. Thus the dimerisation and IKKβ-binding interfaces overlap and lie on a surface used for protein:protein interactions in many viral and cellular Bcl-2-like proteins.

Journal Keywords: Immunosuppressor; Innate Immunity; NF-kappaB; Pox Viruses; Viral Protein

Subject Areas: Biology and Bio-materials

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