Structural basis of specificity of a peptidyl urokinase inhibitor, upain-1.
Urokinase-type plasminogen activator (uPA) plays a crucial role in the regulation of plasminogen activation, tumor cell adhesion and migration. The inhibition of uPA activity is a promising mechanism for anti-cancer therapy. A cyclic peptidyl inhibitor, upain-1, CSWRGLENHRMC, was identified recently as a competitive and highly specific uPA inhibitor. We determined the crystal structure of uPA in complex with upain-1 at 2.15 A. The structure reveals that the cyclic peptide adopts a rigid conformation stabilized by a disulfide bond (residues 1-12) and three tight beta turns (residues 3-6, 6-9, 9-12). The Glu7 residue of upain-1 forms hydrogen bonds with the main chain nitrogen atoms of residues 4, 5, and 6 of upain-1, and is also critical for maintaining the active conformation of upain-1. The Arg4 of upain-1 is inserted into the uPA's specific S1 pocket. The Ser2 residue of upain-1 locates close to the S1beta pocket of uPA. The Gly5 and Glu7 residues of upain-1 occupy the S2 pocket and the oxyanion hole of uPA, respectively. Furthermore, the Asn8 residue of upain-1 binds to the 37- and 60-loops of uPA and renders the specificity of upain-1 for uPA. Based on this structure, a new pharmacophore for the design of highly specific uPA inhibitors was proposed.
Zhao
Gengxiang
G
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, 155 Yang Qiao Xi Lu, Fuzhou, Fujian 350002, China.
Yuan
Cai
C
Wind
Troels
T
Huang
Zixiang
Z
Andreasen
Peter A
PA
Huang
Mingdong
M
D000595:Amino Acid Sequence; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000737:chemistry / Q000494:pharmacology*; D011487:Protein Conformation; D014568:Urokinase-Type Plasminogen Activator / Q000037:antagonists & inhibitors*
D004791:Enzyme Inhibitors; D010456:Peptides, Cyclic; C506777:upain-1 peptide; D014568:Urokinase-Type Plasminogen Activator