2026-08-29T14:12:12Zhttps://repisalud.isciii.es/rest/oai/request

oai:repisalud.isciii.es:20.500.12105/258992025-12-18T12:56:53Zcom_20.500.12105_2173com_20.500.12105_2051col_20.500.12105_19597

00925njm 22002777a 4500 dc Del Caño-Ochoa, Francisco author Ramadane-Morchadi, Lobna author Eixerés, Lluís author Moreno-Morcillo, María author Fernández-Leiro, Rafael author Ramón-Maiques, Santiago author 2024-12-01 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. J Mol Biol . 2024 Dec 1;436(23):168832. Journal of Molecular Biology 39447673 https://hdl.handle.net/20.500.12105/25899 aspartate transcarbamoylase dihydroorotase inborn errors of metabolisms pathogenic variant pyrimidine nucleotide biosynthesis Disruption of CAD Oligomerization by Pathogenic Variants.