V. cholerae MakA is a cholesterol-binding pore-forming toxin that induces non-canonical autophagy

Abstract

Pore-forming toxins (PFTs) are important virulence factors produced by many pathogenic bacteria. Here, we show that the Vibrio cholerae toxin MakA is a novel cholesterol-binding PFT that induces non-canonical autophagy in a pH-dependent manner. MakA specifically binds to cholesterol on the membrane at pH < 7. Cholesterol-binding leads to oligomerization of MakA on the membrane and pore formation at pH 5.5. Unlike other cholesterol-dependent cytolysins (CDCs) which bind cholesterol through a conserved cholesterol-binding motif (Thr-Leu pair), MakA contains an Ile-Ile pair that is essential for MakA-cholesterol interaction. Following internalization, endosomal acidification triggers MakA pore-assembly followed by ESCRT-mediated membrane repair and V-ATPase-dependent unconventional LC3 lipidation on the damaged endolysosomal membranes. These findings characterize a new cholesterol-binding toxin that forms pores in a pH-dependent manner and reveals the molecular mechanism of host autophagy manipulation.

Vibrio parahaemolyticus thermostable direct haemolysin induces non‐classical programmed cell death despite caspase activation

“…For example, vacuolating cytotoxin (VacA) of Helicobacter pylori can cause dysfunctional autophagy leading to apoptosis (Yahiro et al, 2015). A newly identified cytotoxin MakA of Vibrio cholerae can induce non‐canonical autophagy and apoptotic death in the target nucleated cells (Jia et al, 2022; Nadeem et al, 2021). In another recent study, Vibrio cholerae cytolysin (VCC) has been shown to trigger pore formation‐independent apoptotic cell death in its target cells (Kaur et al, 2022).…”

The V-ATPase/ATG16L1 axis is controlled by the V1H subunit

“…CASM can be triggered by pathogen-encoded proton channels (Beale et al, 2014; Ulferts et al, 2021; Jia et al, 2022), proton-selective ionophore drugs (Jacquin et al, 2017; Fletcher et al, 2018), or the alkalisation of phagosomes (in a process termed LC3-Associated Phagocytosis, or LAP) (Sanjuan et al, 2007; Fletcher et al, 2018; Hooper et al, 2022). Recently, the innate immune signalling protein STING has also been shown to induce CASM via proton channel activity within the Golgi, reinforcing its connection to the neutralisation of acidic compartments (Fischer et al, 2020; Liu et al, 2023).…”

Chemogenetic inhibition of IST1-CHMP1B interaction impairs endosomal recycling and promotes unconventional LC3 lipidation at stalled endosomes

“…A prevalent mechanism of non-canonical ATG8 conjugation involves V-ATPase that directly binds ATG16L1 and recruits the ATG12-ATG5-ATG16L1 conjugation complex to membranes 29,30 . Non-canonical ATG8 conjugation has been shown to occur in response to different stimuli and its physiological roles have been demonstrated [31][32][33][34] . Further identification of noncanonical ATG8 conjugation under various stimuli will enhance understanding of its functions and mechanisms.…”