VARIATION IN THE SIZE OF THE REPEAT REGION OF THE FIBRINOGEN RECEPTOR(CLUMPING FACTOR) OF STAPHYLOCOCCUS-AUREUS STRAINS

The ability of Staphylococcus aureus to bind to fibrinogen and fibrin is believed to be an important factor in the initiation of foreign bod y and wound infections, Recently, the gene encoding the fibrinogen rec eptor (clumping factor, ClfA) of S. aureus strain Newman was cloned an d sequenced, The ClfA protein possesses a highly unusual 308 residue d ipeptide repeat region composed predominantly of Asp and Ser. Polymera se chain reaction analysis of seven different strains showed that the size of the clfA repeat coding region varies from 580 bp to 1320 bp, I n contrast, the clfA region A is the same size in each strain. The siz e of the clfA repeat region did not correlate with the ability of thes e strains to form clumps in a solution of fibrinogen, Indeed, the stra in with the smallest repeat size of 580 bp clumped almost as well as s train Newman, Each strain of S, aureus examined contained several high molecular mass proteins that reacted with anti-ClfA region A antibody , In some cases the molecular mass of the major protein varied in acco rdance with the length of the coding sequence for the repeat region R.