4C6B

Crystal structure of the dihydroorotase domain of human CAD with incomplete active site, obtained recombinantly from E. coli.

Summary for 4C6B

• Entry DOI: 10.2210/pdb4c6b/pdb
• Related: 4C6C 4C6D 4C6E 4C6F 4C6I 4C6J 4C6K 4C6L 4C6M 4C6N 4C6O 4C6P 4C6Q
• Descriptor: CAD PROTEIN, FORMIC ACID, GLYCEROL, ... (4 entities in total)
• Functional Keywords: hydrolase, de novo pyrimidine biosynthesis, amidohydrolase superfamily, metalloenzyme, zinc binding, histidinate anion
• Biological source: HOMO SAPIENS (HUMAN)
• Cellular location: Cytoplasm: P27708
• Total number of polymer chains: 1
• Total formula weight: 43195.24

Authors

Ramon-Maiques, S.,Lallous, N.,Grande-Garcia, A. (deposition date: 2013-09-18, release date: 2014-02-05, Last modification date: 2023-12-20)

Primary citation

Grande-Garcia, A.,Lallous, N.,Diaz-Tejada, C.,Ramon-Maiques, S.
Structure, Functional Characterization and Evolution of the Dihydroorotase Domain of Human Cad.
Structure, 22:185-, 2014

PubMed Abstract: Upregulation of CAD, the multifunctional protein that initiates and controls the de novo biosynthesis of pyrimidines in animals, is essential for cell proliferation. Deciphering the architecture and functioning of CAD is of interest for its potential usage as an antitumoral target. However, there is no detailed structural information about CAD other than that it self-assembles into hexamers of ∼1.5 MDa. Here we report the crystal structure and functional characterization of the dihydroorotase domain of human CAD. Contradicting all assumptions, the structure reveals an active site enclosed by a flexible loop with two Zn²⁺ ions bridged by a carboxylated lysine and a third Zn coordinating a rare histidinate ion. Site-directed mutagenesis and functional assays prove the involvement of the Zn and flexible loop in catalysis. Comparison with homologous bacterial enzymes supports a reclassification of the DHOase family and provides strong evidence against current models of the architecture of CAD.

PubMed: 24332717
DOI: 10.1016/J.STR.2013.10.016

Experimental method

X-RAY DIFFRACTION (1.656 Å)