- PMID:
22540246
- Authors:
- Xue Y, Bodin C, Olsson K
- Title:
- Crystal structure of the native plasminogen reveals an activation-resistant compact conformation.
- Journal:
- J Thromb Haemost. 2012 Apr 28. doi: 10.1111/j.1538-7836.2012.04765.x.
- Abstract:
- Background: Plasminogen is the zymogen form of plasmin and the precursor of angiostatin, it has been implicated in a variety of disease states including thrombosis, bleeding and cancers. The native plasminogen, known as Glu-plasminogen, contains seven domains comprising the N-terminal peptide domain (NTP), five kringle domains (K1-K5) and the C-terminal serine protease domain (SP). Previous studies have established that the lysine binding site (LBS) of the conserved kringle domains plays a crucial role in mediating the regulation of plasminogen function. However, details of the related conformational mechanism are unknown. Objectives: We aim to understand in more detail the conformational mechanism of plasminogen activation involving the kringles. Methods: We crystallized the native plasminogen under physiologically relevant conditions and determined the structure at 3.5 A resolution. We performed structural analyses and related to the literature data to gain critical understanding of the plasminogen activation. Results and conclusions: The structure reveals the precise architecture of the quaternary complex. It shows that the Glu-plasminogen renders its compact form as an activation-resistant conformation for the proteolytic activation. The LBSs of all kringles, except K1, are engaged in intra-molecular interactions while only K1-LBS is readily available for ligand binding or receptor anchorage. The structure also provides insights into the interactions between plasminogen and alpha2-antiplasmin, the primary physiological inhibitor of plasmin. Furthermore the data represented explains why a conformational transition to the open form is necessary for plasminogen activation as well as angiostatin generation, and provides a rationale for the functional hierarchy of the different kringles. (c) 2012 International Society on Thrombosis and Haemostasis.