title: Structural basis for recognition of urokinase-type plasminogen activator by plasminogen activator inhibitor-1.
abstract: Plasminogen activator inhibitor-1 (PAI-1), together with its physiological target urokinase-type plasminogen activator (uPA), plays a pivotal role in fibrinolysis, cell migration, and tissue remodeling and is currently recognized as being among the most extensively validated biological prognostic factors in several cancer types. PAI-1 specifically and rapidly inhibits uPA and tissue-type PA (tPA). Despite extensive structural/functional studies on these two reactions, the underlying structural mechanism has remained unknown due to the technical difficulties of obtaining the relevant structures. Here, we report a strategy to generate a PAI-1·uPA(S195A) Michaelis complex and present its crystal structure at 2.3-Å resolution. In this structure, the PAI-1 reactive center loop serves as a bait to attract uPA onto the top of the PAI-1 molecule. The P4-P3' residues of the reactive center loop interact extensively with the uPA catalytic site, accounting for about two-thirds of the total contact area. Besides the active site, almost all uPA exosite loops, including the 37-, 60-, 97-, 147-, and 217-loops, are involved in the interaction with PAI-1. The uPA 37-loop makes an extensive interaction with PAI-1 β-sheet B, and the 147-loop directly contacts PAI-1 β-sheet C. Both loops are important for initial Michaelis complex formation. This study lays down a foundation for understanding the specificity of PAI-1 for uPA and tPA and provides a structural basis for further functional studies.
authors.affiliation: State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.
authors.forename: Zhonghui
authors.initials: Z
authors.lastname: Lin
authors.forename: Longguang
authors.initials: L
authors.lastname: Jiang
authors.forename: Cai
authors.initials: C
authors.lastname: Yuan
authors.forename: Jan K
authors.initials: JK
authors.lastname: Jensen
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.forename: Zhipu
authors.initials: Z
authors.lastname: Luo
authors.forename: Barbara C
authors.initials: BC
authors.lastname: Furie
authors.forename: Bruce
authors.initials: B
authors.lastname: Furie
authors.forename: Peter A
authors.initials: PA
authors.lastname: Andreasen
authors.forename: Mingdong
authors.initials: M
authors.lastname: Huang
mesh_terms: D020134:Catalytic Domain; D003461:Crystallography; D004789:Enzyme Activation / Q000502:physiology; D006801:Humans; D009154:Mutation; D010843:Pichia / Q000235:genetics; D017395:Plasminogen Activator Inhibitor 1 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D014568:Urokinase-Type Plasminogen Activator / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D017395:Plasminogen Activator Inhibitor 1; C051321:SERPINE1 protein, human; D014568:Urokinase-Type Plasminogen Activator