Inhibition of Apoptosis and NF-κB Activation by Vaccinia Protein N1 Occur via Distinct Binding Surfaces and Make Different Contributions to Virulence

PLoS Pathogens

Carlos Maluquer de Motes¹  Gabriel M. F. Almeida¹  Hongwei Ren¹  Kieran McGourty¹  Samantha Cooray¹  Geoffrey L. Smith²  Jonathan M. Grimes²  Stephen C. Graham³  Mohammad W. Bahar³  David I. Stuart³ 

[1] Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom;Science Division, Diamond Light Source, Didcot, United Kingdom;The Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom

关键词: Transcription factors;    Apoptosis;    Vaccinia virus;    Protein expression;    Immunoprecipitation;    Mitochondria;    Polymerase chain reaction;    Signal inhibition;   

DOI  :  10.1371/journal.ppat.1002430

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Vaccinia virus (VACV) protein N1 is an intracellular virulence factor and belongs to a family of VACV B-cell lymphoma (Bcl)-2-like proteins whose members inhibit apoptosis or activation of pro-inflammatory transcription factors, such as interferon (IFN) regulatory factor-3 (IRF-3) and nuclear factor-κB (NF-κB). Unusually, N1 inhibits both apoptosis and NF-κB activation. To understand how N1 exerts these different functions, we have mutated residues in the Bcl-2-like surface groove and at the interface used to form N1 homodimers. Mutagenesis of the surface groove abolished only the N1 anti-apoptotic activity and protein crystallography showed these mutants differed from wild-type N1 only at the site of mutation. Conversely, mutagenesis of the dimer interface converted N1 to a monomer and affected only inhibition of NF-κB activation. Collectively, these data show that N1 inhibits pro-inflammatory and pro-apoptotic signalling using independent surfaces of the protein. To determine the relative contribution of each activity to virus virulence, mutant N1 alleles were introduced into a VACV strain lacking N1 and the virulence of these viruses was analysed after intradermal and intranasal inoculation in mice. In both models, VACV containing a mutant N1 unable to inhibit apoptosis had similar virulence to wild-type virus, whereas VACV containing a mutant N1 impaired for NF-κB inhibition induced an attenuated infection similar to that of the N1-deleted virus. This indicates that anti-apoptotic activity of N1 does not drive virulence in these in vivo models, and highlights the importance of pro-inflammatory signalling in the immune response against viral infections.

【 授权许可】

CC BY