Cloning and sequencing of the genes for A and B subunits of the V-type Na +-ATPase of a facultatively anaerobic alkaliphile

Abstract

The structural genes for A and B subunits of the V-type Na +-ATPase from a facultatively anaerobic alkaliphile ( Amphibacillus sp.), strain M-12, were cloned and sequenced. Transformation of Escherichia coli with the genes overexpressed two proteins, which crossreacted with an antiserum against A and B subunits of the V-type Na +-ATPase from Enterococcus hirae. The deduced amino acid sequence (594 amino acids; Mr, 66,144) of A subunit of the M-12 enzyme exhibited 73%, 51%, 49% and 53% identities with those of V-type ATPases from E. hirae, Thermus thermophilus, Neurospora crassa and Drosophila melanogaster, respectively. The amino acid sequence (458 amino acids; Mr, 51,308) of B subunit of the M-12 enzyme was 74%, 53%, 52% and 54% identical with those of the ATPases from E. hirae, T. thermophilus, N. crassa and D. melanogaster, respectively. The fact indicates that the amino acid sequences of A and B subunits of the M-12 enzyme exhibit significantly higher homologies with those of the E. hirae Na +-ATPase as compared with those of the H +-ATPases from T. thermophilus, N. crassa and D. melanogaster.