5INW
Structure of reaction loop cleaved lamprey angiotensinogen
Summary for 5INW
| Entry DOI | 10.2210/pdb5inw/pdb |
| Descriptor | Putative angiotensinogen, C-terminal peptide of Putative angiotensinogen, SULFATE ION, ... (4 entities in total) |
| Functional Keywords | angiotensinogen, serpin, heparin binding, hormone |
| Biological source | Lampetra fluviatilis (European river lamprey) More |
| Total number of polymer chains | 4 |
| Total formula weight | 101455.80 |
| Authors | |
| Primary citation | Wei, H.,Cai, H.,Wu, J.,Wei, Z.,Zhang, F.,Huang, X.,Ma, L.,Feng, L.,Zhang, R.,Wang, Y.,Ragg, H.,Zheng, Y.,Zhou, A. Heparin Binds Lamprey Angiotensinogen and Promotes Thrombin Inhibition through a Template Mechanism J.Biol.Chem., 291:24900-24911, 2016 Cited by PubMed Abstract: Lamprey angiotensinogen (l-ANT) is a hormone carrier in the regulation of blood pressure, but it is also a heparin-dependent thrombin inhibitor in lamprey blood coagulation system. The detailed mechanisms on how angiotensin is carried by l-ANT and how heparin binds l-ANT and mediates thrombin inhibition are unclear. Here we have solved the crystal structure of cleaved l-ANT at 2.7 Å resolution and characterized its properties in heparin binding and protease inhibition. The structure reveals that l-ANT has a conserved serpin fold with a labile N-terminal angiotensin peptide and undergoes a typical stressed-to-relaxed conformational change when the reactive center loop is cleaved. Heparin binds l-ANT tightly with a dissociation constant of ∼10 nm involving ∼8 monosaccharides and ∼6 ionic interactions. The heparin binding site is located in an extensive positively charged surface area around helix D involving residues Lys-148, Lys-151, Arg-155, and Arg-380. Although l-ANT by itself is a poor thrombin inhibitor with a second order rate constant of 500 m s, its interaction with thrombin is accelerated 90-fold by high molecular weight heparin following a bell-shaped dose-dependent curve. Short heparin chains of 6-20 monosaccharide units are insufficient to promote thrombin inhibition. Furthermore, an l-ANT mutant with the P1 Ile mutated to Arg inhibits thrombin nearly 1500-fold faster than the wild type, which is further accelerated by high molecular weight heparin. Taken together, these results suggest that heparin binds l-ANT at a conserved heparin binding site around helix D and promotes the interaction between l-ANT and thrombin through a template mechanism conserved in vertebrates. PubMed: 27681598DOI: 10.1074/jbc.M116.725895 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.7 Å) |
Structure validation
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