Inhibitory effect of modified bafilomycins and concanamycins on P- and V-type adenosinetriphosphatases

Abstract

Various ATPases have been tested for their sensitivity to naturally occurring unusual macrolides and their chemically modified derivatives, which are structurally related to bafilomycin A1 (1), the first specific inhibitor of vacuolar ATPases. The structure-activity study showed that in general the concanamycins, 18-membered macrolides, are better and more specific inhibitors than the bafilomycins of this class of membrane-bound ATPases. The additional carbohydrate residue is not responsible for the improved activity. The importance of an intact hemiketal ring, which is part of an intramolecular hydrogen-bonding network, and the effects of the size of the macrolactone ring are discussed. The structurally related elaiophylin (13), a C2-symmetric macrodiolide antibiotic, proved to be inactive on vacuolar ATPases but still retained its inhibitory effect on P-type ATPases.

Estimating the rotation rate in the vacuolar proton-ATPase in native yeast vacuolar membranes

“…These 'other' inhibitors removed only about 20% of the total ATPase activity, even at relatively high inhibitor concentration. Di-cyclohexyl-carbodiimide, which inhibits proton translocation also in the related F-ATPase (see, e.g., (Kopecky et al 1981;Kopecky et al 1982;Kopecky et al 1983;Hermolin and Fillingame 1989;Wada et al 2000)), was more potent, but the most potent inhibitors were, as expected, concanamycin A and bafilomycin, even when applied at the lowest concentrations (Bowman et al 1988;Drose et al 1993;Gagliardi et al 1999;Huss et al 2002;Dixon et al 2008). In this system, and under the present conditions, these inhibitors removed ~60% of the total ATPase activity, which varied to some extent from isolation to isolation.…”

“…It should be noted that the dissociation constant, K, of concanamycin A binding to VATPase is much larger than in some early reports (Bowman et al 1988;Drose et al 1993) but similar to a more recent report (Whyteside et al 2005;Dixon et al 2008). In addition to the difference in the host systems, this discrepancy might be caused by several factors as explained in (Whyteside et al 2005), of which, the most likely might be a potential removal of a structural component (e.g., polypeptide or lipid) required for a higher affinity binding.…”

The vacuolar ATPase proton pump is required for the cytotoxicity of Bacillus anthracis lethal toxin

“…Concanamycin A, bafilomycins A1, B1, C1 and D were prepared and purified as described previously [11,12]. They were dissolved in dimethyl sulfoxide at a concentration of 1 mM and stored in aliquots at -80°C.…”

“…Bafilomycins (A1, B1, C and D) and concanamycin A are specific inhibitors of the vacuolar ATPase proton pump (V-ATPase) [11,12]. This pump is responsible for the lumenal acidic pH of several intracellular compartments including early and late endosomes and lysosomes [13,14].…”

Hygrobafilomycin, a cytotoxic and antifungal macrolide bearing a unique monoalkylmaleic anhydride moiety, from Streptomyces varsoviensis

“…These well-known actinomyces metabolites are pharmacologically important, because of their biological activities including antiparasitic, antitumor and immunosuppressant, [2][3][4][5] together with bactericidal, fungicidal, insecticidal and herbicidal effects. [6][7][8] Bafilomycin A1 (2) is a highly potent and specific inhibitor of vacuolar ATPase enzymes, 9,10 and has a role as carrier type K + ionophore, 11 which has led to a considerable interest in these metabolites. However, the practical use of these macrolides has been limited because of fatal toxicity, 12 thus propelling semi-synthetic and biosynthetic engineering programs with the aim to create novel derivatives with better efficacy.…”