Séminaire CIRI : Dr. Martin OBR

Martin OBR (Postdoctoral fellow  Institute of Science and Technology Austria Klosterneuburg - Austria): "Architecture of retroviral capsid explored by cryoelectron tomography and subtomogram averaging"

Family Retroviridae comprises viruses infecting wide range of hosts, including humans
(Human immunodeficiency virus; Human T-lymphotropic virus). The life cycle of retroviruses
contains several unique steps, one of which is proteolytic maturation. During this process, the
immature virus particle is converted to mature. Particularly, the precursor protein Gag is
cleaved to yield Capsid protein, which triggers large-scale structural reorganization of the
virus particle. Capsid protein, and the corresponding part of Gag, form and maintain the
protein lattice, which constitutes the mature and immature capsid, respectively.
Retroviral lattice is a challenging object for structural biology, due to the absence of global
symmetry. The classic techniques, such as X-ray crystallography, are thus of limited
applicability. On the other hand, the versatility of cryo-electron tomography and subtomogram
averaging allows observing ultrastructure of the retrovirus particle, and structure
determination of its building blocks.