Structure determination of the human TRPV1 ankyrin-repeat domain under nonreducing conditions.

TRPV1, a member of the transient receptor potential (TRP) channels family, has been found to be involved in redox sensing. The crystal structure of the human TRPV1 ankyrin-repeat domain (TRPV1-ARD) was determined at 4.5 Å resolution under nonreducing conditions. This is the first report of the crystal structure of a ligand-free form of TRPV1-ARD and in particular of the human homologue. The structure showed a unique conformation in finger loop 3 near Cys258, which is most likely to be involved in inter-subunit disulfide-bond formation. Also, in human TRPV1-ARD it was possible for solvent to access Cys258. This structural feature might be related to the high sensitivity of human TRPV1 to oxidants. ESI-MS revealed that Cys258 did not form an S-OH functionality even under nonreducing conditions.