DOMAIN-STRUCTURE OF THE STAPHYLOCOCCUS-AUREUS COLLAGEN ADHESIN

Sequence analysis of surface proteins from Gram-positive bacteria indi cates a composite organization consisting of unique and repeated segme nts. Thus, these proteins may contain discrete domains that could fold independently. In this paper, we have used a panel of biophysical met hods, including gel permeation chromatography, analytical ultracentrif ugation, circular dichroism, and fluorescence spectroscopy, to analyze the structural organization of the Staphylococcus aureus collagen adh esin, CNA. Our results indicate that the structure, function, and fold ing of the ligand-binding domain (A) are not affected by the presence or absence of the other major domain (B). In addition, little or no in teraction is observed between the nearly identical repeat units within the B domain. We propose that CNA is indeed a mosaic protein in which the different domains previously indicated by sequence analysis opera te independently.