Tributyltin sensitivity of vacuolar-type Na(+)-transporting ATPase from Enterococcus hirae.
Tributyltin chloride (TBT), an environmental pollutant, is toxic to a variety of eukaryotic and prokaryotic organisms. Some members of F-ATP synthase (F-ATPase)/vacuolar type ATPase (V-ATPase) superfamily have been identified as the molecular target of this compound. TBT inhibited the activities of H(+)-transporting or Na(+)-transporting F-ATPase as well as H(+)-transporting V-ATPase originated from various organisms. However, the sensitivity to TBT of Na(+)-transporting V-ATPase has not been investigated. We examined the effect of TBT on Na(+)-transporting V-ATPase from an eubacterium Enterococus hirae. The ATP hydrolytic activity of E. hirae V-ATPase in purified form as well as in membrane-bound form was little inhibited by less than 10 microM TBT; IC50 for TBT inhibition of purified enzyme was estimated to be about 35 microM. Active sodium transport by E. hirae cells, indicating the in vivo activity of this V-ATPase, was not inhibited by 20 microM TBT. By contrast, IC50 of H(+)-transporting V-ATPase of the vacuolar membrane vesicles from Saccharomyces cerevisiae was about 0.2 microM. E. hirae V-ATPase is thus extremely less sensitive to TBT.
Soracom
S
Chardwiriyapreecha
Tomohiro
T
Inoue
Naoko
N
Sugimoto
Takayuki
T
Sekito
Ichiro
I
Yamato
Takeshi
T
Murata
Michio
M
Homma
Yoshimi
Y
Kakinuma
D000251:Adenosine Triphosphatases / Q000187:drug effects*; D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000187:drug effects*; D016983:Enterococcus / Q000187:drug effects / Q000201:enzymology*; D017136:Ion Transport / Q000187:drug effects*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism; D014220:Trialkyltin Compounds / Q000633:toxicity*
D001426:Bacterial Proteins; D014220:Trialkyltin Compounds; C011559:tributyltin; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C500332:V-type sodium ATPase, Enterococcus hirae