Dissertations, Theses, and Capstone Projects

Date of Degree

9-2018

Document Type

Dissertation

Degree Name

Ph.D.

Program

Biochemistry

Advisor

Ranajeet Ghose

Committee Members

Avrom J. Caplan

Kevin N. Dalby

David Jeruzalmi

J. Patrick Loria

Subject Categories

Biochemistry | Biophysics | Structural Biology

Keywords

Eukaryotic elongation factor 2 kinase

Abstract

Eukaryotic elongation factor 2 kinase (eEF-2K), the only calmodulin (CaM) dependent member of the a-kinase, phosphorylates eukaryotic elongation factor 2 (eEF-2) on a specific residue (Thr-56), decreasing its affinity for the ribosome and reducing the rate of peptide chain elongation during protein translation. In contrast to the “release-of-inhibition’ mechanism operative in most CaM-dependent proteins kinases, the activation of eEF-2K is proposed to occur through a two-step process subsequent to the engagement of CaM and involves (1) auto-phosphorylation on T348 and (2) engagement of an allosteric site by phospho-T348 leading to a state with the highest activity towards the substrate eEF-2. The precise mechanism of this CaM-mediated activation of eEF-2K and the mode of recruitment of the substrate remain poorly understood.

We utilized a variety of complimentary biophysical techniques including nuclear magnetic resonance spectroscopy (NMR), small angle X-ray scattering (SAXS), and multiple high-resolution mass spectrometric (MS) methods to determine the mechanisms through which CaM engages eEF-2K and induces conformational changes therein en routetowards its fully active state. Our integrative approach provides structural insights into the engagement of eEF-2K by CaM and represents an essential first step in defining the CaM-dependent activation of eEF-2K in atomistic detail.

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