Artículos de revistas
Dissecting the functional roles of the conserved NXXE and HXE motifs of the ADP-dependent glucokinase from Thermococcus litoralis
Fecha
2015Registro en:
FEBS Letters 589 (2015) 3271–3276
0014-5793
DOI: 10.1016/j.febslet.2015.09.013
Autor
Abarca Lagunas, María José
Rivas Pardo, Jaime
Ramírez Sarmiento, César
Giuxé Leguia, Victoria
Institución
Resumen
The activity of the ADP-dependent glucokinase from Thermococcus litoralis (TlGK) relies on the
highly conserved motifs NXXE (i.e. Asn-Xaa-Xaa-Glu) and HXE (i.e. His-Xaa-Glu). Site-directed mutagenesis
of residues Glu279 (HXE) and Glu308 (NXXE) leads to enzymes with highly reduced catalytic
rates. The replacement of Glu308 by Gln increased the KM for MgADP and was activated by free
Mg2+. On the other hand, HXE mutants did not affect the KM for MgADP , were still inhibited by free
Mg2+, and caused a large increase on KM for glucose and an 87-fold weaker binding of glucose onto
the non-hydrolysable TlGK AMP–AlF3 complex. Our findings put forward the fundamental role of
the HXE motif in glucose binding during ternary complex formation