Structural basis for Zn2+-dependent intercellular adhesion in staphylococcal biofilms.
Publication Type:Journal Article
Source:Proc Natl Acad Sci U S A, Volume 110, Issue 3, p.E202-11 (2013)
Keywords:Amino Acid Sequence, Amino Acid Substitution, Bacterial Adhesion, Bacterial Proteins, Base Sequence, Binding Sites, Biofilms, Crystallography, X-Ray, DNA, Bacterial, Humans, Hydrophobic and Hydrophilic Interactions, Membrane Proteins, Models, Molecular, Molecular Sequence Data, Mutagenesis, Site-Directed, Protein Multimerization, Protein Structure, Tertiary, Recombinant Proteins, Repetitive Sequences, Amino Acid, Sequence Homology, Amino Acid, Staphylococcus, Staphylococcus aureus, Staphylococcus epidermidis, Static Electricity, Zinc
<p>Staphylococcal bacteria, including Staphylococcus epidermidis and Staphylococcus aureus, cause chronic biofilm-related infections. The homologous proteins Aap and SasG mediate biofilm formation in S. epidermidis and S. aureus, respectively. The self-association of these proteins in the presence of Zn(2+) leads to the formation of extensive adhesive contacts between cells. This study reports the crystal structure of a Zn(2+) -bound construct from the self-associating region of Aap. Several unusual structural features include elongated β-sheets that are solvent-exposed on both faces and the lack of a canonical hydrophobic core. Zn(2+)-dependent dimers are observed in three distinct crystal forms, formed via pleomorphic coordination of Zn(2+) in trans across the dimer interface. These structures illustrate how a long, flexible surface protein is able to form tight intercellular adhesion sites under adverse environmental conditions.</p>