Preferential acquisition and activation of plasminogen glycoform II by PAM positive group A streptococcal isolates

Authors

David De Oliveira, University of WollongongFollow
Ruby H. P Law, Monash University
Diane Ly, University of WollongongFollow
Simon M. Cook, University of WollongongFollow
Adam J. Quek, Monash University
Jason D. McArthur, University of WollongongFollow
James Whisstock, Monash University
Martina L. Sanderson-Smith, University of WollongongFollow

RIS ID

101847

Publication Details

De Oliveira, D. M.P., Law, R. H. P., Ly, D., Cook, S. M., Quek, A. J., McArthur, J. D., Whisstock, J. C. & Sanderson-Smith, M. L. (2015). Preferential acquisition and activation of plasminogen glycoform II by PAM positive group A streptococcal isolates. Biochemistry, 54 (25), 3960-3968.

Abstract

Plasminogen (Plg) circulates in the host as two predominant glycoforms. Glycoform I Plg (GI-Plg) contains glycosylation sites at Asn289 and Thr346, whereas glycoform II Plg (GII-Plg) is exclusively glycosylated at Thr346. Surface plasmon resonance experiments demonstrated that Plg binding group A streptococcal M protein (PAM) exhibits comparative equal affinity for GI- and GII-Plg in the "closed" conformation (for GII-Plg, KD = 27.4 nM; for GI-Plg, KD = 37.0 nM). When Plg was in the "open" conformation, PAM exhibited an 11-fold increase in affinity for GII-Plg (KD = 2.8 nM) compared with that for GI-Plg (KD = 33.2 nM). The interaction of PAM with Plg is believed to be mediated by lysine binding sites within kringle (KR) 2 of Plg. PAM-GI-Plg interactions were fully inhibited with 100 mM lysine analogue ε-aminocaproic acid (εACA), whereas PAM-GII-Plg interactions were shown to be weakened but not inhibited in the presence of 400 mM εACA. In contrast, binding to the KR1-3 domains of GII-Plg (angiostatin) by PAM was completely inhibited in the presence 5 mM εACA. Along with PAM, emm pattern D GAS isolates express a phenotypically distinct SK variant (type 2b SK) that requires Plg ligands such as PAM to activate Plg. Type 2b SK was able to generate an active site and activate GII-Plg at a rate significantly higher than that of GI-Plg when bound to PAM. Taken together, these data suggest that GAS selectively recruits and activates GII-Plg. Furthermore, we propose that the interaction between PAM and Plg may be partially mediated by a secondary binding site outside of KR2, affected by glycosylation at Asn289.