Edward H. Snell1,2,
Thomas D. Grant1, Joseph R. Luft1,2,
Jennifer Wolfley1, Hiro Tsuruta3,
Stephanie Corretore4, Erin Quartley4, Eric M. Phizicky4,5,
and Elizabeth J. Grayhack4,5
1Hauptman Woodward Medical Research
2Department of Structural Biology, SUNY Buffalo
3Stanford
Synchrotron Radiation Lightsource
4Department of Pediatrics, University of Rochester Medical Center
5Department of Biochemistry and Biophysics, University of Rochester Medical Center
Abstract:
Gln4 is a yeast glutaminyl tRNA synthetase that covalently couples glutamine to the 2'-OH of tRNAGln for its essential role in translation of decoding glutamine codons in mRNA and adding glutamine residues to the growing peptide chain during protein synthesis. Many eukaryotic tRNA synthetases like Gln4 differ from their prokaryotic homologs by the attachment of an additional domain appended to their N or C-terminus, but it is unknown how these domains contribute to tRNA synthetase function, and why they are not found in prokaryotes. We have solved the crystal structure of Gln4 and determined that the N-terminal domain is disordered; 95% of it, over 200 residues, is missing in the structure. We have confirmed that these residues are present in the crystal. The packing diagram shows large water channels which could accommodate this domain in the lattice. Using Small Angle-X-ray Scattering (SAXS), we have determined that this N-terminal domain is dynamic and adopts a range of conformers that can be explained by a single functional pathway. In this talk we will discuss the crystallographic experiment and the SAXS studies. We will describe the development of a novel population distribution analysis that has produced the set of conformers and the computational analysis explaining possible function of the N-terminal domain. We will show how the SAXS data was used to leverage the crystallographic structure and demonstrate that the crystallographic and SAXS structures are completely compatible.
2009 Run
Sept. 23rd to Nov. 10th
