Identification of a plasminogen-binding motif in PAM, a bacterial surface protein.
Surface-associated plasmin(ogen) may contribute to the invasive properties of various cells. Analysis of plasmin(ogen)-binding surface proteins is therefore of interest. The N-terminal variable regions of M-like (ML) proteins from five different group A streptococcal serotypes (33, 41, 52, 53 and 56) exhibiting the plasminogen-binding phenotype were cloned and expressed in Escherichia coli. The recombinant proteins all bound plasminogen with high affinity. The binding involved the kringle domains of plasminogen and was blocked by a lysine analogue, 6-aminohexanoic acid, indicating that lysine residues in the M-like proteins participate in the interaction. Sequence analysis revealed that the proteins contain common 13-16-amino-acid tandem repeats, each with a single central lysine residue. Experiments with fusion proteins and a 30-amino-acid synthetic peptide demonstrated that these repeats harbour the major plasminogen-binding site in the ML53 protein, as well as a binding site for the tissue-type plasminogen activator. Replacement of the lysine in the first repeat with alanine reduced the plasminogen-binding capacity of the ML53 protein by 80%. The results precisely localize the binding domain in a plasminogen surface receptor, thereby providing a unique ligand for the analysis of interactions between kringles and proteins with internal kringle-binding determinants.
Wistedt
A C
AC
Department of Medical Microbiology, University of Lund, Sweden.
Ringdahl
U
U
Müller-Esterl
W
W
Sjøbring
U
U
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D018082:Kringles; D008239:Lysine / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors; D008969:Molecular Sequence Data; D010641:Phenotype; D010958:Plasminogen / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D013297:Streptococcus pyogenes / Q000737:chemistry* / Q000235:genetics
D001426:Bacterial Proteins; D002352:Carrier Proteins; D011994:Recombinant Proteins; C084529:plasminogen-binding protein, bacteria; D010958:Plasminogen; D008239:Lysine