M. Tsivitse et Mdp. Boyle, EVIDENCE FOR INDEPENDENT BINDING DOMAINS WITHIN A GROUP-A STREPTOCOCCAL TYPE IIO IGG-BINDING PROTEIN, Canadian journal of microbiology, 42(11), 1996, pp. 1172-1175
The gene for a type IIo IgG-binding protein has previously been cloned
and sequenced. The similar to 60 000 M(r) recombinant gene product bi
nds all four human IgG subclasses and fibrinogen. Treatment of this re
combinant protein with CNBr results in generation of a series of fragm
ents. One fragment, an similar to 32 000 M(r) polypeptide, binds IgG(1
), IgG(2), and IgG(4) but neither IgG(3) nor fibrinogen. N-terminal am
ino sequencing of this fragment indicated that this was an internal fr
agment of the protein starting at amino acid 186 of the mature protein
. These findings provide evidence for two distinct domains for binding
IgG1, IgG(2), and IgG(4) and binding IgG(3) within a single bacterial
IgG-binding protein.