Mode of substrate binding and specificity for ketohexokinase across isozymes implies an induced-fit mechanism

Date
2022
DOI
Authors
Bae, So Young
Version
OA Version
Citation
Abstract
Ketohexokinase (KHK), in an adenosine triphosphate (ATP) dependent reaction, catalyzes the first reaction in fructose metabolism, which converts the furanose form of D-fructose into fructose-1-phosphate. This enzyme has become a target for pharmacological development against fatty liver and metabolic syndrome. KHK exists in two isoforms, A and C, which differs by alternative splicing of exon 3 which encodes 45 out of 298 amino acids. Normally KHK exists as a homodimer and is comprised of an alpha/beta domain interlocking with a β-clasp domain. For KHK-C, there appear to be at least two conformations of the β-clasp domain. Previous work on KHK-A reveals it does not adopt the same conformations. A structure of the mouse KHK-A in its unliganded form is solved and shows that these two conformations also exist for KHK-A. Furthermore, this property is conserved across species. While crystals of human KHK-A in its unliganded form were grown, a structure was not achieved. However, unpublished structures of human KHK-A in its unliganded form also shows different conformations in β-clasp domain when in juxtaposition with the same enzyme complex with ligands. Defining the role of conformational changes in KHK-A is important, because this isozyme has been reported to have a role in cancer metastasis.
Description
License
Attribution-NoDerivatives 4.0 International