# Bafilomycin
**Bafilomycin** is a macrolide antibiotic produced by *Streptomyces griseus* strains, best known as the first specific inhibitor of the vacuolar-type H⁺-ATPase (V-ATPase), an ATP-driven proton pump that acidifies organelles such as lysosomes and endosomes. Six variants, bafilomycins A1, A2, B1, B2, C1, and C2, were isolated in 1984 from fermentation broths of three *S. griseus* strains (TU 1922, TU 2437, and TU 2599); each carries a 16-membered lactone ring[1](https://pubmed.ncbi.nlm.nih.gov/6423597/). After Bowman and colleagues reported in 1988 that bafilomycin inhibits V-ATPase with high affinity, the compound, especially bafilomycin A1, became a standard biochemical tool for studying this class of proton pumps and for blocking autophagy in cell biology experiments[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC3679948/).
| Key fact | Detail |
|---|---|
| Chemical class | Plecomacrolide macrolide antibiotic with a 16-membered lactone ring and a 6-membered hemiacetal ring joined by a C3-spacer[1](https://pubmed.ncbi.nlm.nih.gov/6423597/) • [2](https://pmc.ncbi.nlm.nih.gov/articles/PMC3679948/) |
| Discovery | Isolated in 1984 from *Streptomyces griseus* strains TU 1922, TU 2437, and TU 2599; variants A1, A2, B1, B2, C1, C2[1](https://pubmed.ncbi.nlm.nih.gov/6423597/) |
| Target | V-ATPase, the first specific inhibitor identified; binds the proteolipid subunit c in the Vo domain[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/) • [4](https://pmc.ncbi.nlm.nih.gov/articles/PMC5703614/) |
| Potency | Inhibits V-ATPases from yeast to mammals at nanomolar concentrations; nearly complete inhibition of proton pumping in the nanomolar range[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/) |
| Mechanism | Sterically blocks rotation of the c-ring against subunit a, preventing proton translocation[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/) |
| Common laboratory use | Classic inhibitor of autophagy; raises lysosomal pH and blocks autophagosome-lysosome fusion[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/) • [5](https://pmc.ncbi.nlm.nih.gov/articles/PMC9604613/) |
| Clinical status | Not in clinical use; limited by a poor toxicity profile and lack of tissue specificity[6](https://onlinelibrary.wiley.com/doi/full/10.1002/med.70003) • [3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/) |
## Discovery and chemical family
Bafilomycin was discovered in the early 1980s as an antifungal metabolite, reported by Werner and colleagues in 1984; in the same period concanamycin was screened as an immunosuppressive compound[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC3679948/). Both belong to the plecomacrolides, an unusual class of macrolide antibiotics defined by a 6-membered hemiacetal ring connected to the macrolactone ring through a C3-spacer. Other natural members found later include hygrolidin (1984), setamycin (1988), leucancidin (1997), and micromonospolide (2001)[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC3679948/).
Early work showed a broad activity spectrum: antifungal, antimalarial, and antiparasitic effects, plus antibacterial activity against [Gram-positive bacteria](https://www.edgepedia.org/gram-positive-bacteria)[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC3679948/). The 1988 finding of high-affinity V-ATPase inhibition redirected the compound's career toward cell biology[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC3679948/). A 1999 review of structure-activity relationships reported that the vinylic methoxy group adjacent to a carbonyl function, the dienic system, and the hydroxy group at position 7 are essential for V-ATPase inhibitory activity, and that none of the synthesized analogs was more potent than the parent compound[7](https://pubmed.ncbi.nlm.nih.gov/10519916/).
## Target and mechanism of inhibition
V-ATPases are ATP-driven proton pumps involved in membrane trafficking, autophagy, apoptosis, bone resorption, and sperm maturation, and they feed into mTORC1, AMPK, Wnt, Notch, TGF-β, and GPCR signaling[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/). The enzyme has two domains: the cytosolic V1 domain hydrolyzes ATP, and the membrane-embedded Vo domain translocates protons. ATP hydrolysis rotates the Vo c-ring, moving protons through the cavity between subunit a and the c-ring[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/).
**Binding site.** [Bafilomycin A1](https://www.edgepedia.org/bafilomycin-a1) binds to the outer surface of the Vo domain on the c-ring, whose subunits c and c″ each contribute four transmembrane helices[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/) • [6](https://onlinelibrary.wiley.com/doi/full/10.1002/med.70003). A cryo-EM structure of bafilomycin A1 bound to native bovine brain V-ATPase, published in 2021, gave the first structural view of the mechanism: when the c-ring rotates, the drug presents steric hindrance that prevents the interactions between subunit a and the c-ring, blocking proton translocation. Four residues on transmembrane helix 8 of subunit a (I790, M794, L797, and L801), conserved across yeast, bovine, and human enzymes, clash with the bound drug, which the authors propose as a general mechanism of inhibition across species[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/).
The same structural work placed bafilomycin in a family pattern shared by other macrolide inhibitors of rotary ATPases. Concanamycin, archazolid, and the plant toxin pea albumin 1 subunit b show overlap with bafilomycin's binding sites, indicating a common inhibition mechanism, and the F-ATPase inhibitor oligomycin likewise blocks c-ring rotation in mitochondrial ATP synthase. The detailed binding modes differ: oligomycin engages the catalytic residue E59 of the F-ATPase c subunit, whereas the homologous residue E139 of V-ATPase subunit c does not participate in bafilomycin A1 binding[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/).
In dose-response assays with purified enzyme, bafilomycin A1 concentrations from 0.006 nM to 6 nM were tested against 0.6 nM V-ATPase, and nearly complete inhibition of proton pumping was observed in the nanomolar range[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/). The plecomacrolides show clear selectivity for V-ATPases over the other ATPase classes, P-ATPase and F-ATPase[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC3679948/).
## Biosynthesis
The producing organism *S. griseus* DSM 2608, formerly reported as Tü 1922, carries an 87.4 kb biosynthetic gene cluster containing 27 open reading frames, confirmed by gene disruption experiments that abolished bafilomycin production[8](https://amb-express.springeropen.com/articles/10.1186/2191-0855-3-24). Five type I polyketide synthase genes (BafSI to BafSV) span 58.5 kb and encode 12 modules that assemble the macrolactone backbone from an isobutyrate starter unit plus acetate, propionate, and methoxymalonyl extender units; downstream genes supply methoxymalonyl-CoA from glycerol, and upstream genes build the flavensomycinyl moiety found in bafilomycin B1[8](https://amb-express.springeropen.com/articles/10.1186/2191-0855-3-24). Bafilomycin biosynthesis has also been characterized in other actinomycetes, including *Streptomyces lohii* and *Kitasatospora setae*[8](https://amb-express.springeropen.com/articles/10.1186/2191-0855-3-24).
## Use as a research tool
**Autophagy.** Bafilomycin A1 is widely used as a classic inhibitor of autophagy[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/). By inhibiting V-ATPase it raises lysosomal pH, which disrupts lysosomal degradation and blocks autophagic flux, and it also hinders the fusion of autophagosomes with lysosomes, making it a late-stage autophagy inhibitor[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC9604613/) • [6](https://onlinelibrary.wiley.com/doi/full/10.1002/med.70003). Blocking lysosomal proton transport also inactivates lysosomal hydrolases, which require low pH for activation[9](https://pmc.ncbi.nlm.nih.gov/articles/PMC4382252/). In animal work the compound is costly and unsuitable for routine use: it must be administered at low doses for short periods, or it disrupts proteasomal and vesicular dynamics[10](https://pmc.ncbi.nlm.nih.gov/articles/PMC5492018/).
**Virology.** Because endosomal acidification is a critical step in influenza A virus entry, bafilomycin A1 has served as a probe of that process. At 5 × 10−7 M it prevented influenza virus entry into cells when added during the first minutes of infection, while virion attachment to the cell surface was unaffected; the related concanamycin A was active at 5 × 10−9 M[11](https://openalex.org/W2134376649). Newer V-ATPase inhibitors targeting the same Vo subunit c region have been explored as antivirals with reduced toxicity[12](https://bpspubs.onlinelibrary.wiley.com/doi/10.1111/j.1476-5381.2011.01346.x).
**Cell trafficking.** In rat hepatocytes, bafilomycin A1 and concanamycin A reduced the uptake of endocytic probes and redistributed the asialoglycoprotein receptor, cutting the number of surface receptors by roughly 40% without changing the total receptor pool[13](https://pubmed.ncbi.nlm.nih.gov/11342162/). In adipocytes, bafilomycin A1 and concanamycin A block the formation of small GLUT4 vesicles and reduce insulin-stimulated glucose transport[14](https://journals.physiology.org/doi/abs/10.1152/ajpendo.00571.2003).
## Investigated therapeutic directions
Cancer has shown selective susceptibility to V-ATPase inhibition[15](https://onlinelibrary.wiley.com/doi/10.1155/2014/675430). In human prostate cancer cell models, nanomolar bafilomycin A or concanamycin A reduced in vitro invasion of both androgen-dependent [LNCaP](https://www.edgepedia.org/lncap) and androgen-independent C4-2B cells by about 80% at 10 nM over 24 hours, under conditions where proliferation was not compromised[16](https://pmc.ncbi.nlm.nih.gov/articles/PMC3504192/). In colon cancer cell lines, very low concentrations of bafilomycin A1 (about 2 nM) selectively induced cell death, accompanied by lysosomal membrane permeabilization, autophagy flux blockade, endoplasmic reticulum stress, and decreased intracellular Fe²⁺ levels[17](https://pmc.ncbi.nlm.nih.gov/articles/PMC11814099/). In primary acute myeloid leukemia cells from 80 consecutive patients, bafilomycin A1 showed dose-dependent antiproliferative and proapoptotic effects that varied considerably between patients[18](https://pmc.ncbi.nlm.nih.gov/articles/PMC10488188/).
Studies have also suggested possible anti-parasitic and anti-neurodegenerative applications, and the 2021 structure has been proposed as a starting point for designing fungal V-ATPase-specific inhibitors as antibiotics against fungal infections[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/).
**Toxicity limits translation.** Most available V-ATPase inhibitors, bafilomycin among them, exhibit cellular toxicity due to a lack of tissue specificity, and their complex structures make synthetic modification difficult[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/). Reviews describe bafilomycin A1's clinical use as limited by a poor toxicity profile, and high concentrations can induce severe acidosis and harm normal cells[6](https://onlinelibrary.wiley.com/doi/full/10.1002/med.70003) • [17](https://pmc.ncbi.nlm.nih.gov/articles/PMC11814099/). One proposed route forward is to tune binding affinity downward, from nanomolar to sub-micromolar, so the drug would spare low-abundance V-ATPase under physiological conditions while still binding the upregulated V-ATPase found in tumor environments[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/).
## References
1. [Werner et al. (1984). Bafilomycins, a new group of macrolide antibiotics. Production, isolation, chemical structure and biological activity. PubMed.](https://pubmed.ncbi.nlm.nih.gov/6423597/)
2. [Hwang et al. (2013). Organization and characterization of a biosynthetic gene cluster for bafilomycin from Streptomyces griseus DSM 2608. AMB Express.](https://pmc.ncbi.nlm.nih.gov/articles/PMC3679948/)
3. [Wang et al. (2021). Molecular basis of V-ATPase inhibition by bafilomycin A1. Nature Communications.](https://pmc.ncbi.nlm.nih.gov/articles/PMC7979754/)
4. [F-actin reorganization by V-ATPase inhibition in prostate cancer. PMC.](https://pmc.ncbi.nlm.nih.gov/articles/PMC5703614/)
5. [Many roads lead to CASM: Diverse stimuli of noncanonical autophagy share a unifying molecular mechanism. PMC.](https://pmc.ncbi.nlm.nih.gov/articles/PMC9604613/)
6. [Cursaro et al. (2025). A Focus on Natural Autophagy Modulators as Potential Host-Directed Weapons Against Emerging and Re-Emerging Viruses. Medicinal Research Reviews.](https://onlinelibrary.wiley.com/doi/full/10.1002/med.70003)
7. [Gagliardi, Rees, Farina (1999). Chemistry and structure activity relationships of bafilomycin A1. Current Medicinal Chemistry.](https://pubmed.ncbi.nlm.nih.gov/10519916/)
8. [Hwang et al. (2013). Biosynthetic gene cluster for bafilomycin from Streptomyces griseus DSM 2608. AMB Express (full text).](https://amb-express.springeropen.com/articles/10.1186/2191-0855-3-24)
9. [Pharmacologic agents targeting autophagy. PMC.](https://pmc.ncbi.nlm.nih.gov/articles/PMC4382252/)
10. [Methods for Measuring Autophagy in Mice. PMC.](https://pmc.ncbi.nlm.nih.gov/articles/PMC5492018/)
11. [Requirement for vacuolar proton-ATPase activity during entry of influenza virus into cells. OpenAlex record.](https://openalex.org/W2134376649)
12. [Müller et al. (2011). The proton translocation domain of cellular vacuolar ATPase provides a target for the treatment of influenza A virus infections. British Journal of Pharmacology.](https://bpspubs.onlinelibrary.wiley.com/doi/10.1111/j.1476-5381.2011.01346.x)
13. [Effects of inhibitors of the vacuolar proton pump on hepatic heterophagy and autophagy. PubMed.](https://pubmed.ncbi.nlm.nih.gov/11342162/)
14. [V-type ATPase is involved in biogenesis of GLUT4 vesicles. American Journal of Physiology-Endocrinology and Metabolism.](https://journals.physiology.org/doi/abs/10.1152/ajpendo.00571.2003)
15. [Holliday (2014). Vacuolar H+-ATPase: An Essential Multitasking Enzyme in Physiology and Pathophysiology. New Journal of Science.](https://onlinelibrary.wiley.com/doi/10.1155/2014/675430)
16. [Inhibitors of Vacuolar ATPase Proton Pumps Inhibit Human Prostate Cancer Cell Invasion. PMC.](https://pmc.ncbi.nlm.nih.gov/articles/PMC3504192/)
17. [Bafilomycin A1 induces colon cancer cell death through impairment of the endolysosome system dependent on iron. PMC.](https://pmc.ncbi.nlm.nih.gov/articles/PMC11814099/)
18. [Vacuolar ATPase Is a Possible Therapeutic Target in Acute Myeloid Leukemia. PMC.](https://pmc.ncbi.nlm.nih.gov/articles/PMC10488188/)
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*Topic: Encyclopedia › Life and health › Biological foundations › Biochemistry and metabolism › Protein families and complexes › ATPases, pumps, and transport protein families › F-, V-, and A-type rotary ATPases › Rotary ATPase inhibitors*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 21, 2026 · Edited: Sep 30, 2026; Oct 21, 2026 · Last review: Oct 21, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license