PMID: 20826823

Authors:

Anthony CS, Corradi HR, Schwager SL, Redelinghuys P, Georgiadis D, Dive V, Acharya KR, Sturrock ED

Title:

The N domain of human angiotensin-I converting enzyme: the role of N-glycosylation and the crystal structure in complex with an N domain specific phosphinic inhibitor RXP407.

Journal:

J Biol Chem. 2010 Sep 8.

Abstract:

ACE plays a critical role in the regulation of blood pressure through its central role in the renin-angiotensin and kallikrein-kinin systems. ACE contains two domains, the N and C domains, both of which are heavily glycosylated. Structural studies of ACE have been fraught with severe difficulties because of surface glycosylation of the protein. In order to investigate the role of glycosylation in the N domain and to create suitable forms for crystallization, we have investigated the importance of the ten potential N-linked glycan sites using enzymatic deglycosylation, limited proteolysis and mass spectrometry. A number of glycosylation mutants were generated via site-directed mutagenesis, expressed in CHO cells and analysed for enzymatic activity and thermal stability. At least seven out of ten of the potential glycan sites are glycosylated; three C-terminal sites were sufficient for expression of active N domain while two N-terminal sites are important for its thermal stability. The minimally glycosylated Ndom389 construct was highly suitable for crystallization studies. The structure in the presence of an N domain selective phosphinic inhibitor RXP407 was determined to 2.0 resolution. The Ndom389 structure revealed a hinge region that may contribute to the breathing motion proposed for substrate binding.