9FS2

Mutant S1538A of the dihydroorotase domain of human CAD protein bound to substrate

Summary for 9FS2

• Entry DOI: 10.2210/pdb9fs2/pdb
• Descriptor: Multifunctional protein CAD, ZINC ION, N-CARBAMOYL-L-ASPARTATE, ... (6 entities in total)
• Functional Keywords: nucleotide metabolism, de novo pyrimidine synthesis, cad disease, multienzymatic protein, zinc, carboxylated lysine, hydrolase
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 1
• Total formula weight: 40780.58

Authors

del Cano-Ochoa, F.,Ramon-Maiques, S. (deposition date: 2024-06-20, release date: 2024-12-04)

Primary citation

Del Cano-Ochoa, F.,Ramadane-Morchadi, L.,Eixeres, L.,Moreno-Morcillo, M.,Fernandez-Leiro, R.,Ramon-Maiques, S.
Disruption of CAD Oligomerization by Pathogenic Variants.
J.Mol.Biol., 436:168832-168832, 2024

PubMed Abstract: 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.

PubMed: 39447673
DOI: 10.1016/j.jmb.2024.168832

Experimental method

X-RAY DIFFRACTION (1.12 Å)