The length of the reactive center loop modulates the latency transition of plasminogen activator inhibitor-1.
Plasminogen activator inhibitor-1 (PAI-1) belongs to the serine protease inhibitor (serpin) protein family, which has a common tertiary structure consisting of three beta-sheets and several alpha-helices. Despite the similarity of its structure with those of other serpins, PAI-1 is unique in its conformational lability, which allows the conversion of the metastable active form to a more stable latent conformation under physiological conditions. For the conformational conversion to occur, the reactive center loop (RCL) of PAI-1 must be mobilized and inserted into the major beta-sheet, A sheet. In an effort to understand how the structural conversion is regulated in this conformationally labile serpin, we modulated the length of the RCL of PAI-1. We show that releasing the constraint on the RCL by extension of the loop facilitates a conformational transition of PAI-1 to a stable state. Biochemical data strongly suggest that the stabilization of the transformed conformation is owing to the insertion of the RCL into A beta-sheet, as in the known latent form. In contrast, reducing the loop length drastically retards the conformational change. The results clearly show that the constraint on the RCL is a factor that regulates the conformational transition of PAI-1.
Na
Yu-Ran
YR
Department of Molecular Biology, Research Center for Conformational Degenerative Diseases, Sejong University, 98 Gunja-dong, Kwangjin-gu, Seoul 143-747, Korea.
Im
Hana
H
D004926:Escherichia coli / Q000201:enzymology; D006801:Humans; D017395:Plasminogen Activator Inhibitor 1 / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry
D017395:Plasminogen Activator Inhibitor 1; D011994:Recombinant Proteins