[S6-4] The trimeric autotransporter adhesin of the highly adhesive Acinetobacter strain Tol 5
Acinetobacter sp. Tol 5, which is a toluene-degrading bacterium that we previously isolated from a biofiltration system, exhibits autoagglutination and high adhesiveness to solid surfaces. Tol 5 cells quickly adhere to various material surfaces from hydrophobic plastics to hydrophilic glasses and metals independently of biofilm formation. This characteristic nonspecific adhesiveness of Tol 5 cells is mediated by AtaA, a member of the trimeric autotransporter adhesin (TAA) family. TAAs are outer membrane proteins of Gram-negative bacteria and have been well-studied as virulence factors because each TAA shows an ability to bind to biotic molecules of host cells, such as collagen and fibronectin. Although they have a variety of lengths from several hundreds to several thousands of amino acids, they have a common structure that includes an N-terminal passenger domain (PSD), which is secreted onto the cell surface and is responsible for its function, and a C-terminal transmembrane domain, which anchors the PSD onto the outer membrane. AtaA is one of the largest TAAs consisting of 3,630 amino acids but shares common structural features with other TAAs. However, there have been no reports of TAA-mediated adhesion similar to Tol 5 cells through AtaA in terms of nonspecificity and high stickiness. In this symposium, structural and biophysical features of AtaA are presented.