Modulation of the F1FO-ATPase function by butyltin compounds

Among butyltin compounds, tributyltin (TBT), widely exploited in the past in antifouling paints for its biocidal properties, is long known as one of the most harmful sea contaminants. Among the ascertained and universal toxicity mechanisms, TBT targeting F1FO-ATPase and thus impairing cell bioenergetics, is here reviewed. While TBT effects on F1FO-ATPase have been investigated for decades, the possible impact of the derivatives dibutyltin (DBT) and monobutyltin (MBT), produced by abiotic and/or biotic dealkylation of TBT and usually considered far less toxic, have been poorly explored up until now. Butyltin effects on F1FO-ATPase and their underlying action mechanism seem to be tightly structure dependent. Butyltins are membrane-active toxicants. Owing to its more pronounced lipophilicity TBT targets the transmembrane FO sector, blocks ionic translocation and causes a dose-dependent loss of sensitivity to FO inhibitors such as oligomycin and N,N0-dicyclohexylcarbodiimide. DBT strongly inhibits F1FO-ATPase activity by competing with the Mg+2 cofactor in the F1 catalytic site but is ineffective on the enzyme sensitivity to FO inhibitors. MBT is apparently ineffective. The possible contribution of DBT to the overall butyltin toxicity on membrane systems may not be neglectable since usually TBT coexists with its derivatives in organotin-exposed animal tissues. Copyright © 2013 John Wiley & Sons, Ltd.