4qs8

From Proteopedia

Arabidopsis Hexokinase 1 (AtHXK1) structure in ligand-free form

Structural highlights

4qs8 is a 1 chain structure with sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 1.798Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

HXK1_ARATH Fructose and glucose phosphorylating enzyme. May be involved in the phosphorylation of glucose during the export from mitochondrion to cytosol. Acts as sugar sensor which may regulate sugar-dependent gene repression or activation. Mediates the effects of sugar on plant growth and development independently of its catalytic activity or the sugar metabolism. May regulate the execution of program cell death in plant cells.^[1] ^[2] ^[3]

Publication Abstract from PubMed

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 (AtHXK1(G104D) and AtHXK1(S177A)) 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 2.0 A, respectively. These structures reveal a domain rearrangement of AtHXK1 upon glucose binding. The 2.1 A resolution structure of AtHXK1(S177A) 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.

Biochemical and structural study of Arabidopsis hexokinase 1.,Feng J, Zhao S, Chen X, Wang W, Dong W, Chen J, Shen JR, Liu L, Kuang T Acta Crystallogr D Biol Crystallogr. 2015 Feb;71(Pt 2):367-75. doi:, 10.1107/S1399004714026091. Epub 2015 Jan 23. PMID:25664748^[4]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Moore B, Zhou L, Rolland F, Hall Q, Cheng WH, Liu YX, Hwang I, Jones T, Sheen J. Role of the Arabidopsis glucose sensor HXK1 in nutrient, light, and hormonal signaling. Science. 2003 Apr 11;300(5617):332-6. PMID:12690200 doi:http://dx.doi.org/10.1126/science.1080585
↑ Kim M, Lim JH, Ahn CS, Park K, Kim GT, Kim WT, Pai HS. Mitochondria-associated hexokinases play a role in the control of programmed cell death in Nicotiana benthamiana. Plant Cell. 2006 Sep;18(9):2341-55. Epub 2006 Aug 18. PMID:16920781 doi:http://dx.doi.org/10.1105/tpc.106.041509
↑ Jang JC, Leon P, Zhou L, Sheen J. Hexokinase as a sugar sensor in higher plants. Plant Cell. 1997 Jan;9(1):5-19. PMID:9014361 doi:http://dx.doi.org/10.1105/tpc.9.1.5
↑ Feng J, Zhao S, Chen X, Wang W, Dong W, Chen J, Shen JR, Liu L, Kuang T. Biochemical and structural study of Arabidopsis hexokinase 1. Acta Crystallogr D Biol Crystallogr. 2015 Feb;71(Pt 2):367-75. doi:, 10.1107/S1399004714026091. Epub 2015 Jan 23. PMID:25664748 doi:http://dx.doi.org/10.1107/S1399004714026091