Disruption of CAD Oligomerization by Pathogenic Variants.
Por:
Del Caño-Ochoa F, Ramadane-Morchadi L, Eixerés L, Moreno-Morcillo M, Fernández-Leiro R and Ramón-Maiques S
Publicada:
1 dic 2024
Ahead of Print:
1 nov 2024
Resumen:
CAD, the multi-enzymatic protein essential for initiating the de novo biosynthesis of pyrimidine nucleotides, forms large hexamers whose structure and function are not fully understood. Defects in CAD cause a severe neurometabolic disorder that is challenging to diagnose. We developed a cellular functional assay to identify defective CAD variants, and in this study, we characterized five pathogenic missense mutations in CAD's dihydroorotase (DHO) and aspartate transcarbamoylase (ATC) domains. All mutations impaired enzymatic activities, with two notably disrupting the formation of DHO dimers and ATC trimers. Combining crystal structures and AlphaFold predictions, we modeled the hexameric CAD complex, highlighting the central role of the DHO and ATC domains in its assembly. Our findings provide insight into CAD's stability, function, and organization, revealing that correct oligomerization of CAD into a supramolecular complex is required for its function in nucleotide synthesis and that mutations affecting this assembly are potentially pathogenic.
Filiaciones:
Del Caño-Ochoa F:
Structure of Macromolecular Targets Unit, Instituto de Biomedicina de Valencia (IBV), CSIC, Eduardo Primo Yúfera, 3, 46012 Valencia, Spain
Ramadane-Morchadi L:
Molecular Oncology Laboratory, Hospital Clínico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Prof Marín Lagos, S/N, 28040 Moncloa-Aravaca, Madrid, Spain
Eixerés L:
Structure of Macromolecular Targets Unit, Instituto de Biomedicina de Valencia (IBV), CSIC, Eduardo Primo Yúfera, 3, 46012 Valencia, Spain
Moreno-Morcillo M:
Genome Integrity and Structural Biology Group, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro, 3, 28029 Madrid, Spain
Fernández-Leiro R:
Genome Integrity and Structural Biology Group, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro, 3, 28029 Madrid, Spain
:
Structure of Macromolecular Targets Unit, Instituto de Biomedicina de Valencia (IBV), CSIC, Eduardo Primo Yúfera, 3, 46012 Valencia, Spain
Group CB06/07/0077 Centro de Investigación Biomédica en Red de Enfermedades Raras, CIBERER-ISCIII, Monforte de Lemos 3-5, 28029 Madrid, Spain
Valencia Biomedical Research Foundation, Centro de Investigación Príncipe Felipe (CIPF) - Associated Unit to the Instituto de Biomedicina de Valencia (IBV), Eduardo Primo Yúfera, 3, 46012 Valencia, Spain
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