ANALYSIS OF GENES ENCODING 2 UNIQUE TYPE IIA IMMUNOGLOBULIN G-BINDINGPROTEINS EXPRESSED BY A SINGLE GROUP-A STREPTOCOCCAL ISOLATE

An emm-like gene (emmL) and a fcrA gene from group A streptococcal str ain 64/14 (emmL(64/14) and fcrA(64/14)) were amplified by PCR and forc e cloned into the heat-inducible expression vector pJLA 602. The emml gene encoded a recombinant protein that bound human IgG1, IgG2, and Ig G4 in a nonimmune fashion. This is the reactivity profile of a type II a IgG-binding protein. The emmL(64/14) gene product was antigenically similar to the previously identified high-molecular-weight type IIa Ig G-binding protein of strain-64/14 and had an N-terminal sequence ident ical to that of the wild-type protein. The fcrA gene also encoded a re combinant protein with type IIa functional activity. This protein was similar to the lower-molecular-weight type IIa IgG-binding protein pre viously isolated from strain 64/14 and was antigenically distinct from the higher-molecular-weight type IIa protein encoded by the emmL(64/1 4) gene. The sequences for both genes including: the intervening regio ns are presented. The emmL gene demonstrates significant homology to o ther class I emm and emmL genes expressed by opacity factor-negative g roup A streptococcal isolates. The fcr A gene was found to be homologo us to other fcrA genes normally present in opacity factor-positive gro up A isolates. The sequence upstream of the fcrA gene and the interven ing sequence between the end of the fcrA gene and the start of the emm L gene were similar to those reported for other fcrA genes.