2OAY

Crystal structure of latent human C1-inhibitor

Summary for 2OAY

• Entry DOI: 10.2210/pdb2oay/pdb
• Descriptor: Plasma protease C1 inhibitor, 2-acetamido-2-deoxy-beta-D-glucopyranose, GLYCEROL, ... (4 entities in total)
• Functional Keywords: latent serpin; rcl insertion, immune system, hydrolase inhibitor
• Biological source: Homo sapiens (human)
• Cellular location: Secreted: P05155
• Total number of polymer chains: 1
• Total formula weight: 44400.97

Authors

Harmat, V.,Beinrohr, L.,Gal, P.,Dobo, J. (deposition date: 2006-12-18, release date: 2007-05-01, Last modification date: 2024-10-16)

Primary citation

Beinrohr, L.,Harmat, V.,Dobo, J.,Lorincz, Z.,Gal, P.,Zavodszky, P.
C1 inhibitor serpin domain structure reveals the likely mechanism of heparin potentiation and conformational disease
J.Biol.Chem., 282:21100-21109, 2007

PubMed Abstract: C1 inhibitor, a member of the serpin family, is a major down-regulator of inflammatory processes in blood. Genetic deficiency of C1 inhibitor results in hereditary angioedema, a dominantly inheritable, potentially lethal disease. Here we report the first crystal structure of the serpin domain of human C1 inhibitor, representing a previously unreported latent form, which explains functional consequences of several naturally occurring mutations, two of which are discussed in detail. The presented structure displays a novel conformation with a seven-stranded beta-sheet A. The unique conformation of the C-terminal six residues suggests its potential role as a barrier in the active-latent transition. On the basis of surface charge pattern, heparin affinity measurements, and docking of a heparin disaccharide, a heparin binding site is proposed in the contact area of the serpin-proteinase encounter complex. We show how polyanions change the activity of the C1 inhibitor by a novel "sandwich" mechanism, explaining earlier reaction kinetic and mutagenesis studies. These results may help to improve therapeutic C1 inhibitor preparations used in the treatment of hereditary angioedema, organ transplant rejection, and heart attack.

PubMed: 17488724
DOI: 10.1074/jbc.M700841200

Experimental method

X-RAY DIFFRACTION (2.35 Å)