Bafilomycins: a class of inhibitors of membrane ATPases from microorganisms, animal cells, and plant cells.

Abstract

Various membrane ATPases have been tested for their sensitivity to baflomycin Al, a macrolide antibiotic. F1Fo ATPases from bacteria and mitochondria are not affected by this antibiotic. In contrast, ElE2 ATPases-e.g., the K+-dependent (Kdp) ATPase from Escherichia coli, the Na4+,K+ -ATPase from ox brain, and the Ca2+-ATPase from sarcoplasmic reticulum-are moderately sensitive to this inhibitor. Finally, membrane ATPases from Neurospora vacuoles, chromaffin granules, and plant vacuoles are extremely sensitive. and, in the case of the Na4 ,K4-ATPase, by ouabain (5-11).The vacuolar ATPases appear to hydrolyze ATP, generating a proton gradient that is used for acidification of compartments within cells (12,17,22). This group of ATPases has been distinguished from the other two by virtue of its inhibitor specificity. The vacuolar ATPases are not inhibited by azide, oligomycin, vanadate, or ouabain. Instead, inhibitors that have proved useful for these enzymes include (i) N,N'-dicyclohexylcarbodiimide, which also inhibits F1F0 and E1E2 ATPases, (ii) N-ethylmaleimide, which inhibits E1E2 enzymes (23) and at least one F1F0 ATPase (24), and (iii) NO3 -, which is effective only at millimolar concentrations or greater. Thus, no potent specific inhibitor of vacuolar ATPases has yet been identified.The bafilomycins A1, B1, C1, and D, macrolide antibiotics with a 16-membered lactone ring, were isolated from Streptomyces sp. (25). These compounds inhibited growth of Gram-positive bacteria and fungi in a disc diffusion assay. In addition, it has been reported that bafilomycin C1 inhibits the enzymatic activity of the Na4, 27). In this communication, we compare the effects of bafilomycin A1 on representative enzymes of the three classes of ATPases. The results show that bafilomycin A1 is useful for distinguishing among the different types of ATPases and that it is an extremely potent inhibitor of the vacuolar ATPases.

Rotenone Inhibits Autophagic Flux Prior to Inducing Cell Death

“…The effects of rotenone on LTR mean fluorescence intensity were not as robust as those observed following treatment with 100 nM BafA1, a potent inhibitor of acidic vesicle pH via its direct inhibition of V-ATPase. 41 Epifluorescence microscopy images ( Figure 4C) corroborate our findings via flow cytometry, where compared to vehicle-control-treated cells there is a relative lack of LTR fluorescence following treatment with rotenone or bafilomycin A1. These results indicate that rotenone causes an early and persistent increase in acidic vesicle pH, which may be due possibly to a net decrease in cellular ATP levels and in turn ATP-dependent acidification.…”

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

“…[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. 13,14 In this study, we report the isolation and structure characterization of a cytotoxic antifungal bafilomycin-hygrolidin hybrid, named hygrobafilomycin (6), featuring an unprecedented monoalkylmaleic anhydride moiety, and its biological evaluation using a panel of tumor cell lines.…”

Isolation and structural determination of a new macrolide, makinolide, from the newly isolated Streptomyces sp. MK-30

“…4 Among the bacteria, compounds 1 and 2 showed inhibitory activities only against Micrococcus luteus at the doses of 15 and 50 mg per disc. Bafilomycins have been reported to be specific inhibitors of the membrane ATPase of eucaryotic cells, 8 and recently, 2 was confirmed to exhibit inhibitory activity against vacuolar-type ATPase. 9 Considering the inhibitory mechanism of bafilomycins, the related compounds 1 and 2 were thought to be active against yeast and fungi; however, among the six strains of yeast and fungi that were tested, macrolides 1 and 2 exhibited inhibitory activities against only S. cerevisiae and Mucor hiemalis (Table 2).…”

“…Among the macrolides, bafilomycins 4,5 and setamycin 6,7 are 16-membered macrolides that are reported to exhibit specific membrane ATPase inhibitory activity. 8 In the course of screening for anti-yeast compounds, we isolated a new bafilomycin analog named makinolide (1 in Figure 1a), along with the known macrolide JBIR À100 (2 in Figure 1a) 9,10 from newly isolated strain, Streptomyces sp. MK-30.…”