title: Molecular co-operation between protein PAM and streptokinase for plasmin acquisition by Streptococcus pyogenes.
abstract: Bacterial surface-associated plasmin formation is believed to contribute to invasion, although the underlying molecular mechanisms are poorly understood. To define the components necessary for plasmin generation on group A streptococci we used strain AP53 which exposes an M-like protein ("PAM") that contains a plasminogen-binding sequence with two 13-amino acid residues long tandem repeats (a1 and a2). Utilizing an Escherichia coli-streptococcal shuttle vector, we replaced a 29-residue long sequence segment of Arp4, an M-like protein that does not bind plasminogen, with a single (a1) or the combined a1a2 repeats of PAM. When expressed in E. coli, the purified chimeric Arp/PAM proteins both bound plasminogen, as well as plasmin, and when used to transform group A streptococcal strains lacking the plasminogen-binding ability, transformants with the Arp/PAM constructs efficiently bound plasminogen. Moreover, when grown in the presence of plasminogen, both Arp/PAM- and PAM-expressing streptococci acquired surface-bound plasmin. In contrast, plasminogen activation failed to occur on PAM- and Arp/PAM-expressing streptococci carrying an inactivated streptokinase gene: this block was overcome by exogenous streptokinase. Together, these results provide evidence for an unusual co-operation between a surface-bound protein, PAM, and a secreted protein, streptokinase, resulting in bacterial acquisition of a host protease that is likely to spur parasite invasion of host tissues.
authors.affiliation: Department of Medical Microbiology, University of Lund, S-223 62 Lund, Sweden.
authors.forename: U
authors.initials: U
authors.lastname: Ringdahl
authors.forename: M
authors.initials: M
authors.lastname: Svensson
authors.forename: A C
authors.initials: AC
authors.lastname: Wistedt
authors.forename: T
authors.initials: T
authors.lastname: Renné
authors.forename: R
authors.initials: R
authors.lastname: Kellner
authors.forename: W
authors.initials: W
authors.lastname: Müller-Esterl
authors.forename: U
authors.initials: U
authors.lastname: Sjöbring
mesh_terms: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D005341:Fibrinolysin / Q000378:metabolism*; D010958:Plasminogen / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013297:Streptococcus pyogenes / Q000378:metabolism*; D013300:Streptokinase / Q000378:metabolism*; D014169:Transformation, Bacterial
chemical_list: D000942:Antigens, Bacterial; C062462:Arp4 protein, Streptococcus pyogenes; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D011993:Recombinant Fusion Proteins; C084529:plasminogen-binding protein, bacteria; C014689:streptococcal M protein; D010958:Plasminogen; D013300:Streptokinase; D005341:Fibrinolysin