Vaccinia Virus Immunomodulator A46: A Lipid and Protein-Binding Scaffold for Sequestering Host TIR-Domain Proteins

PLoS Pathogens

Terry K. Smith¹  Tim Skern²  Lynn F. Ten Eyck³  Kristina Djinović-Carugo⁴  Nina Bobik⁵  Adam Round⁶  Gustavo Arruda Bezerra⁶  Sofiya Fedosyuk⁶  Katharina Radakovics⁶  Isabel Usón⁷  Massimo Sammito⁸ 

[1] Biomedical Sciences Research Complex, University of St. Andrews, North Haugh, St. Andrews, Fife Scotland, United Kingdom;Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California, United States of America;European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS, Grenoble, France;European XFEL GmbH, Notkestraße 85, Hamburg, Germany;Georg August University of Göttingen, Department of Structural Chemistry, Tammannstr. 4, Göttingen, Germany;Max F. Perutz Laboratories, Medical University of Vienna, Vienna Biocenter, Dr. Bohr-Gasse 9/3, Vienna, Austria;San Diego Supercomputer Center, University of California, San Diego, La Jolla, California, United States of America;Structural Biology, IBMB-CSIC, Baldiri Reixach, 13–15, Barcelona, Spain

关键词: Protein structure;    Fatty acids;    Crystal structure;    Transcription factors;    Protein structure determination;    Vaccinia virus;    Lipids;    Small-angle scattering;   

DOI  :  10.1371/journal.ppat.1006079

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Vaccinia virus interferes with early events of the activation pathway of the transcriptional factor NF-kB by binding to numerous host TIR-domain containing adaptor proteins. We have previously determined the X-ray structure of the A46 C-terminal domain; however, the structure and function of the A46 N-terminal domain and its relationship to the C-terminal domain have remained unclear. Here, we biophysically characterize residues 1–83 of the N-terminal domain of A46 and present the X-ray structure at 1.55 Å. Crystallographic phases were obtained by a recently developed ab initio method entitled ARCIMBOLDO_BORGES that employs tertiary structure libraries extracted from the Protein Data Bank; data analysis revealed an all β-sheet structure. This is the first such structure solved by this method which should be applicable to any protein composed entirely of β-sheets. The A46(1–83) structure itself is a β-sandwich containing a co-purified molecule of myristic acid inside a hydrophobic pocket and represents a previously unknown lipid-binding fold. Mass spectrometry analysis confirmed the presence of long-chain fatty acids in both N-terminal and full-length A46; mutation of the hydrophobic pocket reduced the lipid content. Using a combination of high resolution X-ray structures of the N- and C-terminal domains and SAXS analysis of full-length protein A46(1–240), we present here a structural model of A46 in a tetrameric assembly. Integrating affinity measurements and structural data, we propose how A46 simultaneously interferes with several TIR-domain containing proteins to inhibit NF-κB activation and postulate that A46 employs a bipartite binding arrangement to sequester the host immune adaptors TRAM and MyD88.

【 授权许可】

CC BY