Dissecting the role of interprotomer cooperativity in the activation of oligomeric high-temperature requirement A2 protein.
Proc Natl Acad Sci U S A
; 118(35)2021 08 31.
Article
en En
| MEDLINE
| ID: mdl-34446566
ABSTRACT
The human high-temperature requirement A2 (HtrA2) mitochondrial protease is critical for cellular proteostasis, with mutations in this enzyme closely associated with the onset of neurodegenerative disorders. HtrA2 forms a homotrimeric structure, with each subunit composed of protease and PDZ (PSD-95, DLG, ZO-1) domains. Although we had previously shown that successive ligand binding occurs with increasing affinity, and it has been suggested that allostery plays a role in regulating catalysis, the molecular details of how this occurs have not been established. Here, we use cysteine-based chemistry to generate subunits in different conformational states along with a protomer mixing strategy, biochemical assays, and methyl-transverse relaxation optimized spectroscopy-based NMR studies to understand the role of interprotomer allostery in regulating HtrA2 function. We show that substrate binding to a PDZ domain of one protomer increases millisecond-to-microsecond timescale dynamics in neighboring subunits that prime them for binding substrate molecules. Only when all three PDZ-binding sites are substrate bound can the enzyme transition into an active conformation that involves significant structural rearrangements of the protease domains. Our results thus explain why when one (or more) of the protomers is fixed in a ligand-binding-incompetent conformation or contains the inactivating S276C mutation that is causative for a neurodegenerative phenotype in mouse models of Parkinson's disease, transition to an active state cannot be formed. In this manner, wild-type HtrA2 is only active when substrate concentrations are high and therefore toxic and unregulated proteolysis of nonsubstrate proteins can be suppressed.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Enfermedad de Parkinson
/
Regiones Promotoras Genéticas
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Dominios PDZ
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Serina Peptidasa A2 que Requiere Temperaturas Altas
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Mitocondrias
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Mutación
Tipo de estudio:
Etiology_studies
Límite:
Animals
/
Humans
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Año:
2021
Tipo del documento:
Article