*Seminar Series: IMB Seminar Series
*Location: QBP Auditorium, Bld 80
*Date: 29/09/2017
*Time: 12.30

Speaker #1 details
*Title of talk: Cryo-EM structural studies of Mammalian Mitochondrial Respiratory Supercomplexes
*Speaker's name: Dr James Letts
*Speaker's organisation: Institute of Science and Technology, Austria
Speaker's city/state/country: Austria
Website:
Talk Abstract: Mitochondrial electron transport chain complexes I, III and IV are organized into supercomplexes responsible for carrying out cellular respiration. Using electron cryo-microscopy, three architectures of mammalian (sheep) supercomplexes were determined. Distinct arrangements of supercomplex I+III2+IV (the respirasome)—a major \'tight\' form and a minor \'loose\' form (resolved at the resolution of 5.8 Å and 6.7 Å, respectively) were solved along with a supercomplex I+III2 at 7.8 Å resolution. Along side we also determined the first nearly complete atomic structure of isolated mitochondrial complex I at 3.9 Å resolution. With this structure and the known crystal structures of isolated complex III2 and complex IV all observed density in the respirasome could be attributed to the known 80 subunits of the individual complexes, including 132 transmembrane helices. Together these represent the first complete architectures of the dominant, physiologically relevant state of the electron transport chain. More recently, using a novel preparation of functional mitochondrial supercomplex I+III2 this structure has now been resolved to 4.0 Å resolution with multiple supercomplex classes showing alternate conformation around the quinone binding site of complex I indicative of an active to deactive transition.
Speaker's bio: Dr. James A Letts undertook his undergraduate degree in Biochemistry and Microbiology at the University of Victoria in British Columbia, Canada. During this time, he joined the X-ray crystallography laboratory of Dr. Stephen Evans, where he studied the structures of glycosyltransferase enzymes. For his doctoral research he joined the MacKinnon laboratory at Rockefeller University in New York, where he studied membrane protein structure and function focusing on characterization of the human voltage-gated proton channel. As a Maria Skłodowska-Curie postdoctoral fellow in Dr. Leonid Sazanov\'s group at the IST Austria, he gained extensive experience in single particle electron cryo-microscopy applying this technique to solve the structures of large membrane protein complexes and supercomplexes of the mammalian mitochondria electron transport chain.

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Other Details:
*Host name: Dr Irina Vetter
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*Host email: imbevents@uq.edu.au