In this talk, I will present recent progress made in our laboratory on the development and application of solid-state NMR spectroscopy for gaining atomic-level information on the molecular mechanisms of i) HIV-1 assemblies of CA and Gag proteins; and ii) microtubule-associated protein assemblies. I will discuss the advantages of an integrated approach involving solid-state and solution NMR, electron microscopy (EM), and molecular dynamics simulations for characterizing structure and dynamics of protein assemblies. HIV-1 capsid proteins (CA) assemble into cone-like structures and enclose the viral RNA genome together with a small complement of proteins during viral maturation. CA exhibits structural polymorphism and can assemble into various morphologies, such as cones, tubes, and spheres. The origins of conformational plasticity as revealed by ultrahigh resolution MAS NMR studies of structure and dynamics of CA assemblies of varied morphologies will be discussed. Dynactin multisubunit assembly is the activator of the cytoplasmic microtubule-based dynein retrograde motor complex. CAP-Gly microtubule binding domain of dynactin's p150Glued subunit is critical for the regulation of dynein's motility. Mutations in the CAP-Gly domain are associated with neurological disorders, but the mechanism by which the CAP-Gly domain recognizes microtubules remains largely unknown, particularly at the atomic level. 3D structure and residue- specific dynamics on nano- to millisecond timescales determined in our lab from a suite of multidimensional MAS NMR experiments will be presented. Together with our recent MAS NMR studies of CAP-Gly/microtubule complex and solution NMR analysis of neurologically important CAP-Gly mutants these investigations yield insights on the interactions of CAP-Gly with microtubules. Looking into the future, I will conclude the presentation by an overview of emerging methods that will enable structural studies of complex macromolecular assemblies and push the envelope of the systems currently accessible for atomic-resolution analysis.

Probing structure and dynamics of HIV-1 and microtubule-associated protein assemblies

245th National Meeting (2013)

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