Molecular Co-operation between Protein PAM and Streptokinase for Plasmin Acquisition by Streptococcus pyogenes

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 …