Nucleotide-binding sites in V-type Na+-ATPase from Enterococcus hirae.
Enterococcus hirae V-ATPase, in contrast to most V-type ATPases, is resistant to N-ethylmaleimide (NEM). Alignment of the amino acid sequences of NtpA suggests that the NEM-sensitive Cys of V-type ATPases is replaced by Ala in E. hirae V-ATPase. Consistent with this prediction, the V-ATPase became sensitive upon substitution of the Ala with Cys. The three-dimensional structure of the NtpB subunit of V-ATPase was modeled based on the structure of the corresponding subunit (alpha subunit) of bovine F(1)-ATPase by homology modeling. Overall, the 3D structure of the subunit resembled that of alpha subunit of bovine F(1)-ATPase. The NtpB subunit, which lacks the P-loop consensus sequence for nucleotide binding, was predicted to bind a nucleotide at the modeled nucleotide-binding site. Experimental data supported the prediction that the E. hirae V-ATPase had about six nucleotide-binding sites.
Murata
Takeshi
T
The Medical Research Council Dunn Human Nutrition Unit, Hills Road, Cambridge CB2 2XY, UK.
Yoshikawa
Yasushi
Y
Hosaka
Toshiaki
T
Takase
Kazuma
K
Kakinuma
Yoshimi
Y
Yamato
Ichiro
I
Kikuchi
Takeshi
T
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D016983:Enterococcus / Q000378:metabolism*; D005033:Ethylmaleimide / Q000494:pharmacology; D008969:Molecular Sequence Data; D006180:Proton-Translocating ATPases / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism*
D013439:Sulfhydryl Reagents; D012964:Sodium; D000251:Adenosine Triphosphatases; D025262:Vacuolar Proton-Translocating ATPases; D006180:Proton-Translocating ATPases; D005033:Ethylmaleimide