Coxsackievirus and adenovirus receptor amino-terminal immunoglobulin V-related domain binds adenovirus type 2 and fiber knob from adenovirus type 12

The extracellular region of the coxsackievirus and adenovirus receptor (CAR ) is predicted to consist of two immunoglobulin (Ig)-related structural dom ains. We expressed the isolated CAR amino-terminal domain (D1) and a CAR fr agment containing both extracellular Ig domains (D1/D2) in Escherichia coli . Both D1 and D1/D2 formed complexes in vitro with the recombinant knob dom ain of adenovirus type 12 (Ad12) fiber, and D1 inhibited adenovirus type 2 (Ad2) infection of HeLa cells. These results indicate that the adenovirus-b inding activity of CAR is localized in the amino-terminal IgV-related domai n and confirm our earlier observation that Ad2 and Ad12 bind to the same ce llular receptor, Preliminary crystallization studies suggest that complexes of Ad12 knob bound to D1 will be suitable For structure determination.