Hexokinase 1 from Arabidopsis thaliana (AtHXK1) plays a dual role in glycolysis and sugar sensing for vital metabolic and physiological processes. The uncoupling of glucose signalling from glucose metabolism was demonstrated by the analysis of two mutants (AtHXK1G104D and AtHXK1S177A) that are catalytically inactive but still functional in signalling. In this study, substrate-binding experiments indicate that the two catalytically inactive mutants have a high affinity for glucose, and an ordered substrate-binding mechanism has been observed for wild-type AtHXK1. The structure of AtHXK1 was determined both in its inactive unliganded form and in its active glucose-bound form at resolutions of 1.8 and 2.0Å, respectively. These structures reveal a domain rearrangement of AtHXK1 upon glucose binding. The 2.1Å resolution structure of AtHXK1S177A in the glucose-bound form shows similar glucose-binding interactions as the wild type. A glucose-sensing network has been proposed based on these structures. Taken together, the results provide a structural explanation for the dual functions of AtHXK1.
|Number of pages||9|
|Journal||Acta Crystallographica Section D: Biological Crystallography|
|Publication status||Published - Feb 1 2015|
- domain reorientation
- sugar sensor
ASJC Scopus subject areas
- Structural Biology