title: The role of beta-strand 5A of plasminogen activator inhibitor-1 in regulation of its latency transition and inhibitory activity by vitronectin.
abstract: Plasminogen activator inhibitor-1 (PAI-1) is a potential target for anti-thrombotic and anti-cancer therapy. It circulates in plasma in a complex with vitronectin (VN). We have studied biochemical mechanisms for PAI-1 neutralisation and its modulation by VN, using site-directed mutagenesis and limited proteolysis. We demonstrate that VN, besides delaying conversion of PAI-1 to the inactive latent form, also protects PAI-1 against cold- and detergent-induced substrate behaviour and counteracts conversion of PAI-1 to inert forms by certain amphipathic organochemical compounds. VN protection against cold- and detergent-induced substrate behaviour is associated with inhibition of the proteolytic susceptibility of beta-strand 5A. Alanine substitution of a lysine residue placed centrally in beta-strand 5A implied a VN-induced acceleration of latency transition, instead of the normal delay. This substitution not only protects PAI-1 against neutralisation, but also counteracts VN-induced protection against neutralisation. We conclude that beta-strand 5A plays a crucial role in VN-regulation of PAI-1 activity.
authors.affiliation: Laboratory of Cellular Protein Science, Department of Molecular and Structural Biology, Aarhus University, Gustav Wieds vej 10C, DK-8000 Aarhus C, Denmark. sgj@mbio.aau.dk
authors.forename: Signe
authors.initials: S
authors.lastname: Jensen
authors.forename: Tove
authors.initials: T
authors.lastname: Kirkegaard
authors.forename: Katrine E
authors.initials: KE
authors.lastname: Pedersen
authors.forename: Marta
authors.initials: M
authors.lastname: Busse
authors.forename: Klaus T
authors.initials: KT
authors.lastname: Preissner
authors.forename: Kees W
authors.initials: KW
authors.lastname: Rodenburg
authors.forename: Peter A
authors.initials: PA
authors.lastname: Andreasen
mesh_terms: D019943:Amino Acid Substitution; D010450:Endopeptidases / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D017395:Plasminogen Activator Inhibitor 1 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019096:Vitronectin / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D017395:Plasminogen Activator Inhibitor 1; D011994:Recombinant Proteins; D019096:Vitronectin; D010450:Endopeptidases