Year: 2007
Type: dissertation
Abstract: The crisis of rising antibiotic resistance in human pathogens calls for the development of new antibiotics. The methionine recycling enzyme, 5-methylthioribose (MTR) kinase, has been identified as a drug target because it is a key enzyme in bacterial methionine salvage and is absent in mammalian cells. As the first step of structure-based drug design, the structure of MTR kinase from B. subtilis was determined in several states in the reaction coordinate (apo, ADP, ADP-PO4, AMPPCP and AMPPCP-MTR), while the A. thaliana enzyme was determined in complex with ADP. These crystal structures represent the first structural studies of MTR kinases. The crystallographic phases were determined by a novel nucleotide-holmium derivative. The technique of holmium phasing can be a general strategy for determining the crystal structure of many medically relevant proteins that bind nucleotide and metal ions. MTR kinase exhibits structural features that include a glycine rich G-loop, a catalytic HGD-motif, a Mg(II)-binding DXE-motif, a semi-conserved W-loop and a MTR-binding RR-motif. Although MTR kinase related to eukaryotic protein kinases the enzyme reveals a unique mode of nucleotide binding, raising questions on the role of metal coordination in the protein kinase-like superfamily. MTR kinase does not appear to display inter-lobal motions during catalysis as in a protein kinase, shedding light on the link between inter-lobal conformational changes and regulation of enzyme activity. Finally, the analysis of MTR kinase structures in the ground states has so far favoured a dissociative mechanism of phosphate transfer.
Source: TSpace (University of Toronto)
Author: Ku, Shao-Yang
Institution: University of Toronto
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7133023282