CLONING OF AAS, A GENE ENCODING A STAPHYLOCOCCUS-SAPROPHYTICUS SURFACE PROTEIN WITH ADHESIVE AND AUTOLYTIC PROPERTIES

A gene encoding a novel cell wall-associated protein of Staphylococcus saprophyticus that binds fibronectin and to sheep erythrocytes has be en cloned and sequenced. The 4392 bp open reading frame codes for an a mino acid sequence that is quite similar to the Atl, an autolysin, of Staphylococcus aureus and to the AtlE of S. epidermidis. The two regio ns of most pronounced homology code for an N-acetyl-muramyl-L-alanine amidase and for an endo-beta-N-acetyl-Dglucosaminidase. The cloned pro tein lysed cells of S. saprophyticus and Micrococcus luteus exogenousl y. Subcloning localized the enzymatic activities to the regions of hig h homology and demonstrated that the interposed sequence is responsibl e for the adhesive activities. Two allelic replacement mutants were co nstructed that lacked autolytic activity and adhesive properties. The N-terminal portion of the protein contains seven highly conserved, con tiguous repeats with no similarity to published sequences. It lacks th e motifs typical of Gram-positive surface proteins and shows a differe nt overall organization. This autolysin/ adhesin of S. saprophyticus ( Aas) appears to represent a new Glass of staphylococcal adhesins.