Characterization of an Extremely Large, Ligand-Induced Conformational Change in Plasminogen

Abstract

Native human plasminogen has a radius of gyration of 39 angstroms. Upon occupation of a weak lysine binding site, the radius of gyration increases to 56 angstroms, an extremely large ligand-induced conformational change. There are no intermediate conformational states between the closed and open form. The conformational chang is not accompanied by a change in secondary structure, hence the closed conformation is formed by interaction between domains that is abolished upon conversion to the open form. This reversible change in conformation, in which the shape of the protein changes from that best described by a prolate ellipsoid to a flexible structure best described by a Debye random coil, is physiologically relevant because a weak lysine binding site regulates the activation of plasminogen.

Structural/functional properties of the Glu1‐HSer57 N‐terminal fragment of human plasminogen: Conformational characterization and interaction with kringle domains

“…that, in the absence of lysyl-type ligands, -60-80% of Glul-Pgn assumes a compact, "closed' shape while the rest is in an extended or "open" conformation (Markus, 1996 (Marshall et al, 1994) and -240 (Mangel et al, 1990), respectively, on the basis of the equilibrium open/close (= [K]/[K-NTP]) ratios given above and the estimated molecular volume, one obtains 0.47 < K, < 17.5 mM". Hence, the 2.3 < K, < 6.2 mM" values we have determined via 'H-NMR for the binding of CB-NTP to the isolated, intact kringles fall within range of the affinities that one may estimate from the independent data.…”

“…NTP segment in determining the Pgn global fold (Castellino et al, 1973;Sjoholm et al, 1973;Claeys & Vermylen, 1974;Violand et al, 1975;Markus et al, 1978Markus et al, , 1979Tranqui et al, 1979;Binyai & Patthy, 1984;Mangel et al, 1990;Ramakrishnan et al, 1991 ;Ponting et al, 1992a;Marshall et al, 1994;Weisel et al, 1994). …”

Rapid-reaction Kinetic Characterization of the Pathway of Streptokinase-Plasmin Catalytic Complex Formation

“…K1, K4, and K5 mediate Pg and Pm binding to COOH-terminal lysine residues on fibrin and to lysine and arginine residues of other proteins (19 -24). The LBS located in K5 is thought to be primarily responsible for interactions with the NH 2 -terminal peptide in [Glu]Pg, keeping the zymogen in a spiral, compact ␣-conformation (25)(26)(27)(28). Removal of the NH 2 -terminal peptide by Pm cleavage results in formation of [Lys]Pg, which assumes a partially extended ␤-conformation that is more rapidly activated by tissue-type plasminogen activator and urokinase and by the SK⅐Pg* and SK⅐Pm catalytic complexes (2, 29 -32).…”

39 Structure function relationships of plasminogen activator inhibitor type-2 (PAI-2)

“…The 12kDa N-terminal pre-activation domain appears to be critical for maintenance of the tightly closed spiral conformation of circulating glu-plasminogen through non-covalent interactions with other domains of the protein (Mangel et al 1990;Ponting et al 1992). Removal of the pre-activation domain via plasmin catalysed proteolysis at Lys 76 -Val 77 results in formation of the second in vivo species of plasminogen known as lys-plasminogen.…”