Kinetic characterization and phylogenetic analysis of human ADP-dependent glucokinase reveal new insights into its regulatory properties

Herrera-Morande, Alejandra; Vallejos-Baccelliere, Gabriel; Cea, Pablo A.; Zamora, Ricardo A.; Cid, Dixon; Maturana, Pablo; Gonzalez-Ordenes, Felipe; Castro-Fernandez, Victor; Guixe, Victoria


Although ADP-dependent sugar kinases were first described in archaea, at present, the presence of an ADP -dependent glucokinase (ADP-GK) in mammals is well documented. This enzyme is mainly expressed in he-matopoietic lineages and tumor tissues, although its role has remained elusive. Here, we report a detailed kinetic characterization of the human ADP-dependent glucokinase (hADP-GK), addressing the influence of a putative signal peptide for endoplasmic reticulum (ER) destination by characterizing a truncated form. The truncated form revealed no significant impact on the kinetic parameters, showing only a slight increase in the Vmax value, higher metal promiscuity, and the same nucleotide specificity as the full-length enzyme. hADP-GK presents an ordered sequential kinetic mechanism in which MgADP is the first substrate to bind and AMP is the last product released, being the same mechanism described for archaeal ADP-dependent sugar kinases, in agreement with the protein topology. Substrate inhibition by glucose was observed due to sugar binding to nonproductive species. Although Mg2+ is an essential component for kinase activity, it also behaves as a partial mixed-type inhibitor for hADP-GK, mainly by decreasing the MgADP affinity. Regarding its distribution, phylogenetic analysis shows that ADP-GK's are present in a wide diversity of eukaryotic organisms although it is not ubiquitous. Eukaryotic ADP-GKs sequences cluster into two main groups, showing differences in the highly conserved sugar-binding motif reported for archaeal enzymes [NX(N)XD] where a cysteine residue is found instead of asparagine in a significant number of enzymes. Site directed mutagenesis of the cysteine residue by asparagine produces a 6-fold decrease in Vmax, suggesting a role for this residue in the catalytic process, probably by facilitating the proper orientation of the substrate to be phosphorylated.

Más información

Título según WOS: ID WOS:000991149300001 Not found in local WOS DB
Volumen: 741
Editorial: Elsevier Science Inc.
Fecha de publicación: 2023


Notas: ISI