The ntp operon encoding the Na+V-ATPase of the thermophile Caloramator fervidus

The V-type ATPase of the thermophile Caloramator fervidus is an ATP-driven Na+ pump. The nucleotide sequence of the ntpFIKECGABD operon containing the structural genes coding for the nine subunits of the enzyme complex was determined. The identity of the proteins in two pairs of subunits (D, E and F, G) that have very similar mobilities on SDS-PAGE of the purified complex (24.3 and 22.7 kDa, and 12.3 and 11.6 kDa) was established by tryptic digestion of the protein bands followed by mass spectrometric analysis of the peptides.