Structure and Mechanism of Vacuolar Na+-Translocating ATPase From Enterococcus hirae

V-type Na+-ATPase from Entercoccus hirae consists of nine kinds of subunits (NtpA3, B3, C1, D1, E1−3, F1−3, G1, I1, and K10) which are encoded by the ntp operon. The amino acid sequences of the major subunits, A, B, and K (proteolipid), were highly similar to those of A, B, and c subunits of eukaryotic V-ATPases, and those of β, α, and c subunits of F-ATPases. We modeled the A and B subunits by homology modeling using the structure of β and α subunits of F-ATPase, and obtained an atomic structure of NtpK ring by X-ray crystallography. Here we briefly summarize our current models of the whole structure and mechanism of the E. hirae V-ATPase.