Crystal structure of the N-acetylmannosamine kinase domain of GNE.
BACKGROUND
UDP-GlcNAc 2-epimerase/ManNAc 6-kinase, GNE, is a bi-functional enzyme that plays a key role in sialic acid biosynthesis. Mutations of the GNE protein cause sialurea or autosomal recessive inclusion body myopathy/Nonaka myopathy. GNE is the only human protein that contains a kinase domain belonging to the ROK (repressor, ORF, kinase) family.


RESULTS
We solved the structure of the GNE kinase domain in the ligand-free state. The protein exists predominantly as a dimer in solution, with small populations of monomer and higher-order oligomer in equilibrium with the dimer. Crystal packing analysis reveals the existence of a crystallographic hexamer, and that the kinase domain dimerizes through the C-lobe subdomain. Mapping of disease-related missense mutations onto the kinase domain structure revealed that the mutation sites could be classified into four different groups based on the location - dimer interface, interlobar helices, protein surface, or within other secondary structural elements.


CONCLUSIONS
The crystal structure of the kinase domain of GNE provides a structural basis for understanding disease-causing mutations and a model of hexameric wild type full length enzyme.


BACKGROUND
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Tong
Yufeng
Y
Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada.
Tempel
Wolfram
W
Nedyalkova
Lyudmila
L
Mackenzie
Farrell
F
Park
Hee-Won
HW
D002238:Carbohydrate Epimerases / Q000737:chemistry; D002241:Carbohydrates / Q000737:chemistry; D018360:Crystallography, X-Ray / Q000379:methods; D019281:Dimerization; D006801:Humans; D008024:Ligands; D008968:Molecular Conformation; D009135:Muscular Diseases / Q000378:metabolism; D009154:Mutation; D020125:Mutation, Missense; D016366:Open Reading Frames; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
D002241:Carbohydrates; D008024:Ligands; D002238:Carbohydrate Epimerases; C100033:UDP acetylglucosamine-2-epimerase