Arginine-178 is an essential residue for ITPA function.
DEE 35
Epileptic encephalopathy
ITP
ITPA
Inosine
Purine metabolism disorders
Journal
Archives of biochemistry and biophysics
ISSN: 1096-0384
Titre abrégé: Arch Biochem Biophys
Pays: United States
ID NLM: 0372430
Informations de publication
Date de publication:
08 2023
08 2023
Historique:
received:
20
06
2023
revised:
18
07
2023
accepted:
22
07
2023
pmc-release:
01
08
2024
medline:
7
8
2023
pubmed:
29
7
2023
entrez:
28
7
2023
Statut:
ppublish
Résumé
The inosine triphosphate pyrophosphatase (ITPA) enzyme plays a critical cellular role by removing noncanonical nucleoside triphosphates from nucleotide pools. One of the first pathological ITPA mutants identified is R178C (rs746930990), which causes a fatal infantile encephalopathy, termed developmental and epileptic encephalopathy 35 (DEE 35). The accumulation of noncanonical nucleotides such as inosine triphosphate (ITP), is suspected to affect RNA and/or interfere with normal nucleotide function, leading to development of DEE 35. Molecular dynamics simulations have shown that the very rare R178C mutation does not significantly perturb the overall structure of the protein, but results in a high level of structural flexibility and disrupts active-site hydrogen bond networks, while preliminary biochemical data indicate that ITP hydrolyzing activity is significantly reduced for the R178C mutant. Here we report Michaelis-Menten enzyme kinetics data for the R178C ITPA mutant and three other position 178 ITPA mutants. These data confirm that position 178 is essential for ITPA activity and even conservative mutation at this site (R178K) results in significantly reduced enzyme activity. Our data support that disruption of the active-site hydrogen bond network is a major cause of diminished ITP hydrolyzing activity for the R178C mutation. These results suggest an avenue for developing therapies to address DEE 35.
Identifiants
pubmed: 37506994
pii: S0003-9861(23)00199-6
doi: 10.1016/j.abb.2023.109700
pmc: PMC10530447
mid: NIHMS1921446
pii:
doi:
Substances chimiques
Inosine
5A614L51CT
Pyrophosphatases
EC 3.6.1.-
Inosine Triphosphate
132-06-9
Arginine
94ZLA3W45F
Nucleotides
0
Types de publication
Journal Article
Research Support, N.I.H., Extramural
Langues
eng
Sous-ensembles de citation
IM
Pagination
109700Subventions
Organisme : NIGMS NIH HHS
ID : R15 GM112121
Pays : United States
Informations de copyright
Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.
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