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Solving the Structure of Eukaryotic Type III Glutamine Synthetase Assembles


EMSL Project ID
50983

Abstract

There are three major classes of the enzyme Glutamine Synthetase (GS) that share widely conserved active-site residues but vary in average protein length, oligomeric assembly state and cofactor requirements. Structures are known for all prokaryotic and eukaryotic variants except eukaryotic class III glutamine synthetase (GSIII), which also has unresolved basic questions about the functional oligomeric state. Here, we propose to solve the near-atomic structure of eukaryotic GSIII from the ancient green algae Ostreococcus tauri by cryo-electron microscopy (Cryo-EM) and single particle analysis. This particular protein exists as a hexamer rather than the canonical dodecamer and is functionally active but has higher tolerance against typical inhibitors. It is also the only isoform of GS present in this organism and the lack of other isoforms is a rarity when GSIII exists in cells. For this PNCC project we plan to determine the structure of O. tauri GSIII in the apo-form, in presence of a common GS inhibitor and also in the presence of its products ADP and glutamine to reveal the overall mechanism underlying this unique variant of GS.

Project Details

Start Date
2019-06-15
End Date
2019-12-14
Status
Closed

Team

Principal Investigator

James Evans
Institution
Environmental Molecular Sciences Laboratory

Team Members

Theo Humphreys
Institution
Oregon Health & Science University

Irina El Khoury
Institution
Environmental Molecular Sciences Laboratory