SCAF by TIR domains; signalling by cooperative assembly formation by d…

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  • 2017-01-06


[BK21 Plus Seminar]
                      ▶Subject: SCAF by TIR domains; signalling by cooperative assembly formation by domains that function in animal and plant innate immunity pathways
                      ▶Speaker: Prof. Bostjan Kobe (School of Chemistry and Molecular Biosciences, University of Queensland)

                      ▶Date: 10:30AM/Nov. 10(Thu.)/2016
                      ▶Place: Conference room(#179), Postech Biotech Center
                      TIR (Toll/interleukin-1 receptor, resistance protein) domains are key components of innate immunity signaling pathways. They are found in animals, plants and bacteria, for example in TLRs (Toll-like receptors) and TLR adaptors in animals, NLRs (nucleotide binding, leucine-rich repeat receptors) in plants, and virulence factors interfering with immune responses in bacteria. While it has been well established that signaling depends on regulated self-association and homotypic association of TIR domains, every single TIR domain structure has revealed a different association mode [1]. In the search for common features, we have targeted a number of TIR domains from mammals, plants and bacteria to characterize structurally. We determined a number of TIR-domain crystal structures, including the human TLR adaptor proteins MAL [2] and SARM (unpublished), the bacterial protein TcpB from Brucella melitensis [3] and the plant immune proteins L6 from flax [4], RPS4 and RRS1 from Arabidopsis [5], SNC1 and RPP1 from Arabidopsis and MrRPV1 from grapevine (unpublished). These crystal structures have started revealing common trends in the TIR-domain association modes, in particular for bacterial and plant TIR domains. Furthermore, for the TLR adaptors MAL and MyD88, we have been able to reconstitute large assemblies and determine the structure for the former by cryo-electron microscopy, while the latter is  being characterized by synchrotron and X-FEL-based serial crystallography. Jointly, these studies suggest a general mechanism of function of TIR domains, which involves "signalling by cooperative assembly formation (SCAF)" with prion-like features that is consistent with signaling in other innate immunity pathways.
 [1]Ve T, Williams S and Kobe B, “Structure and function of Toll/interleukin-1 receptor/resistance protein (TIR) domains”, Apoptosis, 20 (2015), 250-61
 [2]Valkov E et al, “Crystal structure of TLR adaptor MAL/TIRAP reveals the molecular basis for signal transduction and disease protection”, Proc Natl Acad Sci USA, 108 (2011), 14879-14884
 [3]Alaidarous M et al, “Mechanism of bacterial interference with TLR4 signaling by Brucella TIR-domain-containing protein TcpB”, J Biol Chem, 289 (2014), 654-68
 [4]Bernoux M et al, “Structural and functional analysis of a plant resistance protein TIR domain reveals interfaces for self-association, signaling and autoregulation”, Cell Host Microbe, 9 (2011), 200-211
 [5]Williams SJ et al, “Structural basis for assembly and function of a heterodimeric plant immune receptor”, Science 344 (2014), 299-303

                    ▶Inquiry: Prof. Sohn, Kee Hoon (279-2357)
                          * This seminar will be given in English.
                      please refrain from taking photos during seminars. *