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Conformationally organized lysine isosteres in Streptococcus pyogenes M protein mediate direct high-affinity binding to human plasminogen.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2017 Sep 08; Vol. 292 (36), pp. 15016-15027. Date of Electronic Publication: 2017 Jul 19. - Publication Year :
- 2017
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Abstract
- The binding of human plasminogen (hPg) to the surface of the human pathogen group A Streptococcus pyogenes (GAS) and subsequent hPg activation to the protease plasmin generate a proteolytic surface that GAS employs to circumvent host innate immunity. Direct high-affinity binding of hPg/plasmin to pattern D GAS is fully recapitulated by the hPg kringle 2 domain (K2 <subscript>hPg</subscript> ) and a short internal peptide region (a1a2) of a specific subtype of bacterial surface M protein, present in all GAS pattern D strains. To better understand the nature of this binding, critical to the virulence of many GAS skin-tropic strains, we used high-resolution NMR to define the interaction of recombinant K2 <subscript>hPg</subscript> with recombinant a1a2 (VKK38) of the M protein from GAS isolate NS455. We found a 2:1 (m/m) binding stoichiometry of K2 <subscript>hPg</subscript> /VKK38, with the lysine-binding sites of two K2 <subscript>hPg</subscript> domains anchored to two regions of monomeric VKK38. The K2 <subscript>hPg</subscript> /VKK38 binding altered the VKK38 secondary structure from a helical apo-peptide with a flexible center to an end-to-end K2 <subscript>hPg</subscript> -bound α-helix. The K2 <subscript>hPg</subscript> residues occupied opposite faces of this helix, an arrangement that minimized steric clashing of K2 <subscript>hPg</subscript> We conclude that VKK38 provides two conformational lysine isosteres that each interact with the lysine-binding sites in K2 <subscript>hPg</subscript> Further, the adoption of an α-helix by VKK38 upon binding to K2 <subscript>hPg</subscript> sterically optimizes the side chains of VKK38 for maximal binding to K2 <subscript>hPg</subscript> and minimizes steric overlap between the K2 <subscript>hPg</subscript> domains. The mechanism for hPg/M protein binding uncovered here may facilitate targeting of GAS virulence factors for disease management.<br /> (© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.)
Details
- Language :
- English
- ISSN :
- 1083-351X
- Volume :
- 292
- Issue :
- 36
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 28724633
- Full Text :
- https://doi.org/10.1074/jbc.M117.794198