Fluoride-dependent interruption of the transport cycle of a CLC Cl-/H+ antiporter.

The epitope residues were calculated from [PDB: 4KJP, 4KJQ, 4KJW, 4KK5, 4KK6, 4KKL, 4KK9, 4KKB, 4KKC, 4LOU AND 4KK8] as the antigen residues at 4Å atomic distance from the antibody. [PDB: 4JKP and 4KKL] lack contact residue K243. The epitope of the anti-CLC Fab on E148A CLC-ec1, a bacterial Cl-/H+ antiporter, was determined from the crystal structure of the complex, solved by molecular replacement. The complex was equilibrated with 20 mM fluoride and 20 mM bromide. The CLC-ec1 deltaNC construct is truncated at the N and C termini and contains mutation E148A. The structure contains two Fab molecules each bound to the two subunits of the homodimeric channel.