5gs0
Crystal structure of the complex of TLR3 and bi-specific diabody
Structural highlights
DiseaseTLR3_HUMAN Defects in TLR3 are associated with herpes simplex encephalitis type 2 (HSE2) [MIM:613002. HSE is a rare complication of human herpesvirus 1 (HHV-1) infection, occurring in only a small minority of HHV-1 infected individuals. HSE is characterized by hemorrhagic necrosis of parts of the temporal and frontal lobes. Onset is over several days and involves fever, headache, seizures, stupor, and often coma, frequently with a fatal outcome. Note=TLR3 mutations predispose otherwise healthy individuals to isolated herpes simplex encephalitis through a mechanism that involves impaired IFNs production and reduced immune defense against viral infection in the central nervous system.[1] FunctionTLR3_HUMAN Key component of innate and adaptive immunity. TLRs (Toll-like receptors) control host immune response against pathogens through recognition of molecular patterns specific to microorganisms. TLR3 is a nucleotide-sensing TLR which is activated by double-stranded RNA, a sign of viral infection. Acts via MYD88 and TRAF6, leading to NF-kappa-B activation, cytokine secretion and the inflammatory response.[2] [3] [4] [5] [6] [7] Publication Abstract from PubMedBuilding a sophisticated protein nano-assembly requires a method for linking protein components in a predictable and stable structure. Diabodies are engineered antibody fragments that are composed of two Fv domains connected by short peptide linkers. They are attractive candidates for mediators in assembling protein nano-structures because they can simultaneously bind to two different proteins and are rigid enough to be crystallized. However, comparison of previous crystal structures demonstrates that there is substantial structural diversity in the Fv interface region of diabodies and, therefore, reliable prediction of its structure is not trivial. Here, we present the crystal structures of ten mono- and bi-specific diabodies. We found that changing an arginine residue in the Fv interface to threonine greatly reduced the structural diversity of diabodies. We also found that one of the bispecific diabodies underwent an unexpected process of chain swapping yielding a non-functional monospecific diabody. In order to further reduce structural flexibility and prevent chain shuffling, we introduced disulfide bridges in the Fv interface regions. The disulfide-bridged diabodies have rigid and predictable structures and may have applications in crystallizing proteins, analyzing cryo-electron microscopic images and building protein nano-assemblies. Crystal structures of mono- and bi-specific diabodies and reduction of their structural flexibility by introduction of disulfide bridges at the Fv interface.,Kim JH, Song DH, Youn SJ, Kim JW, Cho G, Kim SC, Lee H, Jin MS, Lee JO Sci Rep. 2016 Sep 29;6:34515. doi: 10.1038/srep34515. PMID:27682821[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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