title: Ace is a collagen-binding MSCRAMM from Enterococcus faecalis.
abstract: A putative collagen-binding MSCRAMM, Ace, of Enterococcus faecalis was identified by searching bacterial genome data bases for proteins containing domains homologous to the ligand-binding region of Cna, the collagen-binding MSCRAMM from Staphylococcus aureus. Ace was predicted to have a molecular mass of 71 kDa and contains features characteristic of cell surface proteins on Gram-positive bacteria, including a LPXTG motif for cross-linking to the cell wall. The N-terminal region of Ace contained a region (residues 174-319) in which 56% of the residues are identical or similar when compared with the minimal ligand-binding region of Cna (Cna 151-318); the remainder of the Ace A domain has 46% similarity with the corresponding region of the Cna A domain. Antibodies raised against recombinant Ace A domain were used to verify the cell surface expression of Ace on E. faecalis. These antibodies also effectively inhibited the adhesion of enterococcal cells to a collagen substrate, suggesting that Ace is a functional collagen-binding MSCRAMM. Structural modeling of the conserved region in Ace (residues 174-319) suggested a structure very similar to that reported for residues 151-318 of the Cna collagen-binding domain in which the ligand-binding site was identified as a trench transversing a beta-sheet face (Symersky, J., Patti, J. M., Carson, M., House-Pompeo, K., Teale, M., Moore, D., Jin, L., DeLucas, L. J., Höök, M., and Narayana, S. V. L. (1997) Nat. Struct. Biol. 10, 833-838). Biochemical analyses of recombinant Ace and Cna A domains supported the modeling data in that the secondary structures were similar as determined by CD spectroscopy and both proteins bound at multiple sites in type I collagen with micromolar affinities, but with different apparent kinetics. We conclude that Ace is a collagen-binding MSCRAMM on enterococci and is structurally and functionally related to the staphylococcal Cna protein.
authors.affiliation: Center for Extracellular Matrix Biology, Institute of Biosciences and Technology, Texas A&M University, Houston, Texas 77030, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Rich
authors.forename: B
authors.initials: B
authors.lastname: Kreikemeyer
authors.forename: R T
authors.initials: RT
authors.lastname: Owens
authors.forename: S
authors.initials: S
authors.lastname: LaBrenz
authors.forename: S V
authors.initials: SV
authors.lastname: Narayana
authors.forename: G M
authors.initials: GM
authors.lastname: Weinstock
authors.forename: B E
authors.initials: BE
authors.lastname: Murray
authors.forename: M
authors.initials: M
authors.lastname: Höök
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry / Q000302:isolation & purification*; D003094:Collagen / Q000378:metabolism*; D013293:Enterococcus faecalis / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: C121675:Ace protein, Enterococcus; D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D002352:Carrier Proteins; D011994:Recombinant Proteins; C048165:adhesin, Staphylococcus aureus; D003094:Collagen