Raw mass spectrometry data for publication "Vertebrate cellular endolysosome modulating pore-forming protein is negatively regulated by its homologue under environmental oxidative conditions"

<strong>Abstract</strong>: Endolysosomes are key players in cell physiology, including material exchange, immunity and environmental adaptation etc. Bacterial pore-forming toxin aerolysin-like proteins (ALPs) are widely distributed in animals and plants. βγ-CAT is a complex of an ALP (BmALP1) and a trefoil factor (BmTFF3) in the frog <em>Bombina maxima</em>. It is the first example that a secreted endogenous pore-forming protein modulates the biochemical properties of endolysosomes via pore formation in these vesicles. Here, we report the identification of BmALP3, a homologue of BmALP1 that lacks membrane pore formation capacity. Both BmALP3 and BmALP1 contain a conserved cysteine in their C-terminal regions. BmALP3 was readily oxidized to disulfide bond linked homodimer, and the homodimer could then oxidize BmALP1 via disulfide bond exchange, resulting in the dissociation of βγ-CAT subunits and elimination of its biological activity. Consistent with its behavior <em>in vitro</em>, BmALP3 senses environmental oxygen tension <em>in vivo</em>, leading to modulation of βγ-CAT activity. Interestingly, this C-terminal cysteine site is well conserved in numerous vertebrate ALPs. These findings, for the first time, uncovered the existence of a regulatory ALP (BmALP3) and its modulating action on a cell executive ALP (BmALP1) in a redox-dependent manner, which is completely different from that of bacterial toxin aerolysins.