The first two authors contributed equally to this article.
Understanding carbamoyl-phosphate synthetase I (CPS1) deficiency by using expression studies and structure-based analysis†
Article first published online: 18 MAY 2010
© 2010 Wiley-Liss, Inc.
Volume 31, Issue 7, pages 801–808, July 2010
How to Cite
Pekkala, S., Martínez, A. I., Barcelona, B., Yefimenko, I., Finckh, U., Rubio, V. and Cervera, J. (2010), Understanding carbamoyl-phosphate synthetase I (CPS1) deficiency by using expression studies and structure-based analysis. Hum. Mutat., 31: 801–808. doi: 10.1002/humu.21272
Communicated by Hans R. Watertham
- Issue published online: 24 JUN 2010
- Article first published online: 18 MAY 2010
- Manuscript Accepted: 14 APR 2010
- Manuscript Received: 14 DEC 2009
- CPS1 deficiency;
- urea cycle diseases;
- inborn errors;
- baculovirus expression system;
- CPS1 structure;
- CPS1 site-directed mutagenesis
Carbamoyl-phosphate synthetase I (CPS1) deficiency (CPS1D), a recessively inherited urea cycle error due to CPS1 gene mutations, causes life-threatening hyperammonemia. The disease-causing potential of missense mutations in CPS1 deficiency can be ascertained with the recombinant CPS1 expression and purification system reported here, which uses baculovirus and insect cells. We study with this system the effects of nine clinical mutations and one polymorphism on CPS1 solubility, stability, activity, and kinetic parameters for NAG. Five of the mutations (p.T471N, p.Q678P, p.P774L, p.R1453Q, and p.R1453W) are first reported here, in three severe CPS1D patients. p.P774L, p.R1453Q, and p.R1453W inactivate CPS1, p.T471N and p.Y1491H greatly decrease the apparent affinity for NAG, p.Q678P hampers correct enzyme folding, and p.S123F, p.H337R, and p.P1411L modestly decrease activity. p.G1376S is confirmed a trivial polymorphism. The effects of the C-terminal domain mutations are rationalized in the light of this domain crystal structure, including the NAG site structure [Pekkala et al. Biochem J 424:211–220]. The agreement of clinical observations and in vitro findings, and the possibility to identify CPS1D patients who might benefit from specific treatment with NAG analogues because they exhibit reduced affinity for NAG highlight the value of this novel CPS1 expression/purification system. Hum Mutat 31:1–8, 2010. © 2010 Wiley-Liss, Inc.