RT Journal Article
SR Electronic
T1 IDH1 and IDH2 mutants identified in cancer lose inhibition by isocitrate because of a change in their binding sites
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 425025
DO 10.1101/425025
A1 Juan P. Bascur
A1 Melissa Alegría-Arcos
A1 Ingrid Araya-Durán
A1 Ezequiel I Juritz
A1 Fernando D González-Nilo
A1 Daniel E Almonacid
YR 2018
UL http://biorxiv.org/content/early/2018/10/20/425025.abstract
AB IDH1 and IDH2 are human enzymes that convert isocitrate (ICT) into α-ketoglutarate (AKG). However, mutations in positions R132 of IDH1 and R140 and R172 of IDH2 cause these enzymes to convert AKG into 2-hydroxyglutarate (2HG). Concurrently, accumulation of 2HG in the cell is correlated with the development of cancer. This activity change is mainly due to the loss of the competitive inhibition by ICT of these enzymes, but the molecular mechanism behind this loss of inhibition is currently unknown. In this work we characterized the inhibition and loss of inhibition of IDH1 and IDH2 by means of the binding energies derived from molecular docking calculations. We characterized the substrate binding sites and how they differ among the mutant and wild type enzymes using a Jaccard similarity coefficient based on the residues involved in binding the substrates. We found that molecular docking effectively identifies the inhibition by ICT in the wild type and mutant enzymes that do not appear in tumors, and the loss of inhibition in the mutant enzymes that appear in tumors. Additionally, we found that the binding sites of the mutant enzymes are different among themselves. Finally, we found that the regulatory segment of IDH1 plays a prominent role in the change of binding sites between the mutant enzymes and the wild-type enzymes. Our findings show that the loss of inhibition is related to variations in the enzyme binding sites. Additionally, our findings show that a drug capable of targeting all IDH1 and IDH2 mutations in cancer is unlikely to be found due to significant differences among the binding sites of these paralogs. Moreover, the methodology developed here, which combines molecular docking calculations with binding site similarity estimation, can be useful for engineering enzymes, for instance, when aiming to modify the substrate affinity of an enzyme.