title: Preferential Acquisition and Activation of Plasminogen Glycoform II by PAM Positive Group A Streptococcal Isolates.
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.
authors.affiliation: †Illawarra Health and Medical Research Institute, School of Biological Sciences, University of Wollongong, Wollongong 2522, Australia.
authors.forename: David M P
authors.initials: DM
authors.lastname: De Oliveira
authors.affiliation: ‡Department of Biochemistry and Molecular Biology, Monash University, Melbourne 3168, Australia.
authors.forename: Ruby H P
authors.initials: RH
authors.lastname: Law
authors.affiliation: †Illawarra Health and Medical Research Institute, School of Biological Sciences, University of Wollongong, Wollongong 2522, Australia.
authors.forename: Diane
authors.initials: D
authors.lastname: Ly
authors.affiliation: †Illawarra Health and Medical Research Institute, School of Biological Sciences, University of Wollongong, Wollongong 2522, Australia.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Cook
authors.affiliation: ‡Department of Biochemistry and Molecular Biology, Monash University, Melbourne 3168, Australia.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Quek
authors.affiliation: †Illawarra Health and Medical Research Institute, School of Biological Sciences, University of Wollongong, Wollongong 2522, Australia.
authors.forename: Jason D
authors.initials: JD
authors.lastname: McArthur
authors.affiliation: ‡Department of Biochemistry and Molecular Biology, Monash University, Melbourne 3168, Australia.
authors.forename: James C
authors.initials: JC
authors.lastname: Whisstock
authors.affiliation: †Illawarra Health and Medical Research Institute, School of Biological Sciences, University of Wollongong, Wollongong 2522, Australia.
authors.forename: Martina L
authors.initials: ML
authors.lastname: Sanderson-Smith
mesh_terms: D000614:Aminocaproates / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D004789:Enzyme Activation; D006031:Glycosylation; D006801:Humans; D018082:Kringles; D010958:Plasminogen / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D013290:Streptococcal Infections / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000614:Aminocaproates; D001426:Bacterial Proteins; D010958:Plasminogen