BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Short Talk 11\, Raminta Venskutonytè - UrdA: structural character ization of a novel enzyme DTSTART;VALUE=DATE-TIME:20191011T080000Z DTEND;VALUE=DATE-TIME:20191011T082000Z DTSTAMP;VALUE=DATE-TIME:20260525T143034Z UID:indico-contribution-142-772@lindico453.srv.lu.se DESCRIPTION:Speakers: Raminta Venskutonytė (Medical Structural Biology\, Lund University)\nUrocanate reductase (UrdA) is a bacterial enzyme that wa s first characterized in\n2012 and shown to reduce urocanic acid resulting in a product imidazole propionate\n(1). Unlike similar enzymes fumarate r eductases\, UrdA hasn’t been well investigated.\nBesides being an intere sting novel enzyme enabling bacteria to grow in anaerobic\nconditions with urocanic acid as electron acceptor (1)\, UrdA was shown to play a\nsignif icant role in human gut microbiota\, as imidazole propionate levels are\ni ncreased in people with type 2 diabetes and it further affects glucose met abolism\n(2).\nTwo domain construct of UrdA\, consisting of a FAD binding and a mobile domain\nwere successfully expressed\, purified and crystalliz ed. Four X-ray structures were\nobtained depicting different states of the enzyme: ADP bound\, FAD bound\,\nsubstrate/FAD bound and in complex with product/FAD. The data reveals the overall\nstructural arrangement of the e nzyme as well as the substrate binding mode and\nconformational changes.\n The role of UrdA in imidazole propionate production in relation to type 2 diabetes\nmakes the first structure of the UrdA of particular importance t o our understanding of\nthis enzyme.\n\nReferences\n1. Bogachev\, A. V. et al. (2012)\, Urocanate reductase of Shewanella. Molecular\nMicrobiology\, 86: 1452-1463.\n2. Koh A. et al. (2018) Microbially Produced Imidazole Pr opionate Impairs Insulin\nSignaling through mTORC1. Cell 175: 947-961.\n\n https://lindico453.srv.lu.se/event/125/contributions/772/ LOCATION:Kulturen Auditorium URL:https://lindico453.srv.lu.se/event/125/contributions/772/ END:VEVENT BEGIN:VEVENT SUMMARY:Keynote 9\, Prof Nieng Yan: How is electrical signal generated? Structural and mechanistic investigations of Nav channels DTSTART;VALUE=DATE-TIME:20191011T070000Z DTEND;VALUE=DATE-TIME:20191011T074000Z DTSTAMP;VALUE=DATE-TIME:20260525T143034Z UID:indico-contribution-142-770@lindico453.srv.lu.se DESCRIPTION:Speakers: Nieng Yan (Princeton University\, USA)\nThe voltage- gated sodium (Nav) channels are responsible for the initiation and propaga tion of action potentials. Being associated with a variety of channelopath ies\, they are targeted by multiple pharmaceutical drugs and natural toxin s. We determined the crystal structure of a bacterial Nav channel NavRh in a potentially inactivated state a few years ago\, which is a homotetramer in primary sequence but exhibits structural asymmetry. Employing the mode rn methods of cryo-EM\, we determined the near atomic resolution structure s of a Nav channel from American cockroach (designated NavPaS) and from el ectric eel (designated EeNav1.4). Most recently\, we have determined the c ryo-EM structures of the human Nav channels\, Nav1.2\, Nav1.4\, and Nav1.7 in complex with distinct auxiliary subunits and toxins.These structures r eveal the folding principle and structural details of the single-chain euk aryotic Nav channels that are distinct from homotetrameric voltage-gated i on channels. Unexpectedly\, the two structures were captured in drasticall y different states. Whereas the structure of NavPaS has a closed pore and the four VSDs in distinct conformations\, that of EeNav1.4 and the human c hannels is open at the intracelluar gate with VSDs exhibiting similar “u p”states. The most striking conformational differenc occurs to the III-I V linker\, which is essential for fast inactivation. Based on the structur al features\, we suggest an allosteric blocking mechanism for fast inactiv ation of Nav channels by the IFM motif. Structural comparison of the confo rmationally distinct Nav channels provides important insights into the ele ctromechanical coupling mechanism of Nav channels and offers the 3D templa te to map hundredes of disease mutations.\n\nhttps://lindico453.srv.lu.se/ event/125/contributions/770/ LOCATION:Kulturen Auditorium URL:https://lindico453.srv.lu.se/event/125/contributions/770/ END:VEVENT BEGIN:VEVENT SUMMARY:Short Talk 10\, Hongyi Xu - Solving the First Novel Protein Struct ure by Micro-Crystal Electron Diffraction DTSTART;VALUE=DATE-TIME:20191011T074000Z DTEND;VALUE=DATE-TIME:20191011T080000Z DTSTAMP;VALUE=DATE-TIME:20260525T143034Z UID:indico-contribution-142-771@lindico453.srv.lu.se DESCRIPTION:Speakers: Hongyi Xu (Stockholm University)\nMicro-crystal elec tron diffraction (MicroED) has shown in recent years to be a promising met hod for determining\nmacromolecular structures (1–5). It enables structu ral biologists to study proteins from micron-sized\n3D crystals that are t oo small to be studied by conventional X-ray crystallography. Furthermore\ , MicroED\ncan be applied to biomolecules of low molecular weight that are beyond what can so far be resolved by single\nparticle cryo-EM (6\,7). Ho wever\, up to now\, all protein structures determined by MicroED had alrea dy been\nsolved previously by X-ray crystallography. Here\, we present for the first time an unknown protein structure\n– an R2lox metalloenzyme – solved using MicroED (8). MicroED data were collected from plate-like crystals\nwith an average size of 2 μm × 2 μm × 0.5 μm. By overcoming challenges in sample handling\, cryo-EM specimen\npreparation\, limited d ata completeness and low signal-to-noise ratio\, we are able to solve the structure\nby molecular replacement with a search model of less than 36% s equence identity. The resulting electrostatic\nscattering potential map at 3.0 Å resolution is of sufficient quality to allow accurate model buildi ng and refinement\,\nproviding biologically relevant information on the en zyme. Our results demonstrate MicroED can be\nused for solving novel prote in structures\, using only standard X-ray crystallography software. These findings\nillustrate that electron crystallography has the potential to be come a widely applicable tool for revealing new\ninsights into protein str ucture and function\, opening up new opportunities for structural biologis ts.\n\nRefrences\n1. Shi\, D.\, Nannenga\, B. L.\, Iadanza\, M. G. & Gonen \, T. eLife 2\, (2013).\n2. Nannenga\, B. L.\, Shi\, D.\, Leslie\, A. G. W . & Gonen\, T. Nat. Methods 11\, 927–930 (2014).\n3. Yonekura\, K.\, Kat o\, K.\, Ogasawara\, M.\, Tomita\, M. & Toyoshima\, C. Proc. Natl. Acad. S ci. 112\, 3368–3373\n(2015).\n4. Clabbers\, M. T. B. et al. Acta Crystal logr. Sect. Struct. Biol. 73\, 738–748 (2017).\n5. Xu\, H. et al. Struct ure\, 26\, 667-675 (2018).\n6. Khoshouei\, M.\, Radjainia\, M.\, Baumeiste r\, W. & Danev\, R. Nat. Commun. 8\, 16099 (2017).\n7. Henderson\, R. Q. R ev. Biophys. 28\, 171 (1995).\n8. Xu\, H. et al. Sci. Adv. 5\, eaax4621 (2 019).\n\nhttps://lindico453.srv.lu.se/event/125/contributions/771/ LOCATION:Kulturen Auditorium URL:https://lindico453.srv.lu.se/event/125/contributions/771/ END:VEVENT END:VCALENDAR