Latency transition of plasminogen activator inhibitor type 1 is evolutionarily conserved

Abstract

Plasminogen activator inhibitor type 1 (PAI-1) is a central regulator of fibrinolysis and tissue remodelling. PAI-1 belongs to the serpin superfamily and unlike other inhibitory serpins undergoes a spontaneous inactivation process under physiological conditions, termed latency transition. During latency transition the solvent exposed reactive centre loop is inserted into the central β-sheet A of the molecule, and is no longer accessible to reaction with the protease. More than three decades of research on mammalian PAI-1 has not been able to clarify the evolutionary advantage and physiological relevance of latency transition. In order to study the origin of PAI-1 latency transition, we produced PAI-1 from Spiny dogfish shark (Squalus acanthias) and African lungfish (Protopterus sp.), which represent central species in the evolution of vertebrates. Although human PAI-1 and the non-mammalian PAI-1 variants share only approximately 50 % sequence identity, our results showed that all tested PAI-1 variants undergo latency transition with a similar rate. Since the functional stability of PAI-1 can be greatly increased by substitution of few amino acid residues, we conclude that the ability to undergo latency transition must have been a specific selection criterion for the evolution of PAI-1. It appears that all PAI-1 molecules must harbour latency transition to fulfil their physiological function, stressing the importance to further pursue a complete understanding of this molecular phenomenon with possible implication to pharmacological intervention. Our results provide the next step in understanding how the complete role of this important protease inhibitor evolved along with the fibrinolytic system.

Long range allostery mediates the regulation of plasminogen activator inhibitor-1 by vitronectin

“…Based on their work we included at least one PAI-1 sequence from mammals, birds, crocodilians, turtles, lizards, snakes, amphibians, lungfish, coelacanths, ray-finned fishes and cartilaginous fishes. We made sure to include all of the sequences for which the active PAI-1 lifetime has been determined experimentally: human (Homo sapiens) (19), mouse (Mus musculus) (69), African lungfish (Protopterus annectens) (36), spiny dogfish (Squalus acanthias) (36) and zebrafish (Danio rerio) (70). We cross-referenced sequences from Chana-Muñoz, et al using BLAST to locate the sequences in UniProt (71) and NCBI, with the exception of the PAI-1 sequence for African lungfish, for cases where we could not find the exact sequence, we substituted the closest database sequence as determined by E-value.…”

Did evolution create a flexible ligand-binding cavity in the urokinase receptor through deletion of a plesiotypic disulfide bond?

“…5A). To probe this proposition further, we performed a continuous deuterium labeling of the different uPAR disulfide variants in the presence or absence of saturating levels of GFD and determined the deuterium uptake values by MS after pepsin digestion with special emphasis on peptide (57)(58)(59)(60)(61)(62)(63)(64)(65)(66). The deuterium uptake plots for this peptide reveals a considerable variability in the flexibility of ␤IE and ␤IF in the different disulfide variants (Fig.…”

“…Deuterium uptake plots for other regions in uPAR are shown in Fig. S5, but none of those show as prominent effects as peptide (57)(58)(59)(60)(61)(62)(63)(64)(65)(66) (reporting on ␤IE and ␤IF).…”

“…It is therefore likely that the co-evolution, which shaped the uPARbinding site in SMB, originally was driven by the interaction between vitronectin and the cognate uPA-inhibitor plasminogen activator inhibitor type 1, in which the hotspot residue for SMB-binding (i.e. Arg 101 ) is conserved in lobe-finned fishes, bony fishes, and cartilaginous fishes (61). Later in evolution, the class of Mammalia presumably developed the uPAR⅐vitronectin interaction through convergent evolution.…”

Biochemical and structural analyses suggest that plasminogen activators coevolved with their cognate protein substrates and inhibitors

“…Sequences of PAI-1, uPA, tPA, and plasminogen were retrieved from the NCBI database using tBLASTn (https:// blast.ncbi.nlm.nih.gov/Blast.cgi) 3 (27) with human protein sequences as a query. For lungfish, the sequences were analogically identified in the de novo assembled transcriptome (28). At least one sequence of tPA, PAI-1, and plasminogen were found in each monophyletic group of vertebrates, whereas uPA was found in all groups except amphibians.…”