Lysenin (also called eiseniapore) is a 297 aa protein that specifically binds to sphingomyelin and cholesterol-containing membranes of mammalian cells, including red blood cells and tissue cells, and induces lysis. It is derived from the coelomic fluid of the earthworm, Eisenia foetida. The protein binds to both sphingomyelin and galactosyl ceramide but not to ceramide or galactosyl sphingosine. It probably causes lysis by producing oligomeric protein pores in the target membrane. Lysenin has been reported to have antibacterial activity. It shows weak motif similarity to crystal protein, CryET33.the crystal structure of the lysenin pore and provide insights into its assembly mechanism. The lysenin pore is assembled from nine monomers via dramatic reorganization of almost half of the monomeric subunit structure leading to a β-barrel pore ∼10 nm long and 1.6-2.5 nm wide. The lysenin pore is devoid of additional luminal compartments as commonly found in other toxin pores. Mutagenic analysis and atomic force microscopy imaging, together with these structural insights, suggest a mechanism for pore assembly for lysenin. These insights are relevant to the understanding of pore formation by other aerolysin-like pore-forming toxins, which often represent crucial virulence factors in bacteria. The mechanism of the voltage dependence of lysenin has been studied revealing that the movement of the voltage domain sensor into a physically different environment that precludes electrostatically bound ions may be an integral part of the gating mechanism (Bryant et al. 2018).

Lysenin forms stable oligomers upon membrane binding and causes cell lysis. To get insight into the mechanism of the transition of lysenin from a soluble to a membrane-bound form, the binding of lysenin to lipid membranes was studied by Hereć et al. (2008). The total content of alpha-helices, turns and loops, and beta-structures did not change when it became membrane bound. The alpha-helical component was oriented at 41 degrees to the normal to the membrane, indicating that this protein segment could be anchored in the hydrophobic core of the membrane (Hereć et al., 2008). Non-permeant dyes could be incorporated into liposomes via lysenin channels by controlling their conducting state with multivalent metal cations (Shrestha et al. 2020). Cu²⁺ ions modulate voltage-gating and hysteresis of lysenin channels (Bogard et al. 2023). Non-viral gene therapy for melanoma uses lysenin from Eisenia foetida (Ren et al. 2024).

The crystal structure of the lysenin pore has been reported (Podobnik et al. 2016). The pore is assembled from nine monomers via dramatic reorganization of almost half of the monomeric subunit structure leading to a β-barrel pore ∼10 nm long and 1.6-2.5 nm wide. Mutagenic analysis and atomic force microscopy imaging suggested a mechanism for pore assembly (Podobnik et al. 2016). The voltage sensor domain strongly affects the voltage regulation only during inactivation (channel closing). In contrast, channel reactivation (reopening) presents a more stable, almost invariant voltage dependency. In the presence of ATP, which binds at a different site in the channel's structure and occludes the conducting pathway, both inactivation and reactivation pathways are significantly affected. Therefore, the movement of the voltage domain sensor into a physically different environment that precludes electrostatically bound ions may be an integral part of the gating mechanism (Bryant et al. 2018).

1.C.43 The Earthworm Lysenin Toxin (Lysenin) Family Lysenin (also called eiseniapore) is a 297 aa protein that specifically binds to sphingomyelin and cholesterol-containing membranes of mammalian cells, including red blood cells and tissue cells, and induces lysis. It is derived from the coelomic fluid of the earthworm, Eisenia foetida. The protein binds to both sphingomyelin and galactosyl ceramide but not to ceramide or galactosyl sphingosine. It probably causes lysis by producing oligomeric protein pores in the target membrane. Lysenin has been reported to have antibacterial activity. It shows weak motif similarity to crystal protein, CryET33.the crystal structure of the lysenin pore and provide insights into its assembly mechanism. The lysenin pore is assembled from nine monomers via dramatic reorganization of almost half of the monomeric subunit structure leading to a β-barrel pore ∼10 nm long and 1.6-2.5 nm wide. The lysenin pore is devoid of additional luminal compartments as commonly found in other toxin pores. Mutagenic analysis and atomic force microscopy imaging, together with these structural insights, suggest a mechanism for pore assembly for lysenin. These insights are relevant to the understanding of pore formation by other aerolysin-like pore-forming toxins, which often represent crucial virulence factors in bacteria. The mechanism of the voltage dependence of lysenin has been studied revealing that the movement of the voltage domain sensor into a physically different environment that precludes electrostatically bound ions may be an integral part of the gating mechanism (Bryant et al. 2018). Lysenin forms stable oligomers upon membrane binding and causes cell lysis. To get insight into the mechanism of the transition of lysenin from a soluble to a membrane-bound form, the binding of lysenin to lipid membranes was studied by Hereć et al. (2008). The total content of alpha-helices, turns and loops, and beta-structures did not change when it became membrane bound. The alpha-helical component was oriented at 41 degrees to the normal to the membrane, indicating that this protein segment could be anchored in the hydrophobic core of the membrane (Hereć et al., 2008). Non-permeant dyes could be incorporated into liposomes via lysenin channels by controlling their conducting state with multivalent metal cations (Shrestha et al. 2020). Cu²⁺ ions modulate voltage-gating and hysteresis of lysenin channels (Bogard et al. 2023). Non-viral gene therapy for melanoma uses lysenin from Eisenia foetida (Ren et al. 2024). The crystal structure of the lysenin pore has been reported (Podobnik et al. 2016). The pore is assembled from nine monomers via dramatic reorganization of almost half of the monomeric subunit structure leading to a β-barrel pore ∼10 nm long and 1.6-2.5 nm wide. Mutagenic analysis and atomic force microscopy imaging suggested a mechanism for pore assembly (Podobnik et al. 2016). The voltage sensor domain strongly affects the voltage regulation only during inactivation (channel closing). In contrast, channel reactivation (reopening) presents a more stable, almost invariant voltage dependency. In the presence of ATP, which binds at a different site in the channel's structure and occludes the conducting pathway, both inactivation and reactivation pathways are significantly affected. Therefore, the movement of the voltage domain sensor into a physically different environment that precludes electrostatically bound ions may be an integral part of the gating mechanism (Bryant et al. 2018). The generalized reaction catalyzed by members of the Lysenin family is: Ions (in) ions (out)
This family belongs to the Aerolysin Superfamily.
References:
Bogard, A., P.W. Finn, A.R. Smith, I.M. Flacau, R. Whiting, and D. Fologea. (2023). Modulation of Voltage-Gating and Hysteresis of Lysenin Channels by Cu Ions. Int J Mol Sci 24:.
Bryant, S., N. Shrestha, P. Carnig, S. Kosydar, P. Belzeski, C. Hanna, and D. Fologea. (2016). Purinergic control of lysenin''s transport and voltage-gating properties. Purinergic Signal 12: 549-559.
Bryant, S.L., T. Clark, C.A. Thomas, K.S. Ware, A. Bogard, C. Calzacorta, D. Prather, and D. Fologea. (2018). Insights into the Voltage Regulation Mechanism of the Pore-Forming Toxin Lysenin. Toxins (Basel) 10:.
Hereć, M., M. Gagoś, M. Kulma, K. Kwiatkowska, A. Sobota, and W.I. Gruszecki. (2008). Secondary structure and orientation of the pore-forming toxin lysenin in a sphingomyelin-containing membrane. Biochim. Biophys. Acta. 1778: 872-879.
Jiao, F., Y. Ruan, and S. Scheuring. (2021). High-speed atomic force microscopy to study pore-forming proteins. Methods Enzymol 649: 189-217.
Kulma, M., M. Dadlez, and K. Kwiatkowska. (2019). Insight into the Structural Dynamics of the Lysenin During Prepore-to-Pore Transition Using Hydrogen-Deuterium Exchange Mass Spectrometry. Toxins (Basel) 11:.
Kwiatkowska, K., R. Hordejuk, P. Szymczyk, M. Kulma, A.B. Abdel-Shakor, A. Płucienniczak, K. Dołowy, A. Szewczyk, and A. Sobota. (2007) Lysenin-His, a sphingomyelin-recognizing toxin, requires tryptophan 20 for cation-selective channel assembly but not for membrane binding. Mol. Membr. Biol. 24: 121-134.
Munguira, N.L.B., A. Barbas, and I. Casuso. (2019). The activity of the pore-forming toxin lysenin is regulated by crowding. Nanotechnology. [Epub: Ahead of Print]
Pang, Y., M. Gou, K. Yang, J. Lu, Y. Han, H. Teng, C. Li, H. Wang, C. Liu, K. Zhang, Y. Yang, and Q. Li. (2019). Crystal structure of a cytocidal protein from lamprey and its mechanism of action in the selective killing of cancer cells. Cell Commun Signal 17: 54.
Podobnik, M., P. Savory, N. Rojko, M. Kisovec, N. Wood, R. Hambley, J. Pugh, E.J. Wallace, L. McNeill, M. Bruce, I. Liko, T.M. Allison, S. Mehmood, N. Yilmaz, T. Kobayashi, R.J. Gilbert, C.V. Robinson, L. Jayasinghe, and G. Anderluh. (2016). Crystal structure of an invertebrate cytolysin pore reveals unique properties and mechanism of assembly. Nat Commun 7: 11598.
Ren, M., L. Yang, L. He, J. Wang, W. Zhao, C. Yang, S. Yang, H. Cheng, M. Huang, and M. Gou. (2024). Non-viral Gene Therapy for Melanoma Using Lysenin from Eisenia Foetida. Adv Sci (Weinh) 11: e2306076.
Sekizawa, Y., T. Kubo, H. Kobayashi, T. Nakajima, and S. Natori. (1997). Molecular cloning of cDNA for lysenin, a novel protein in the earthworm Eisenia foetida that causes contraction of rat vascular smooth muscle. Gene. 191: 97-102.
Shogomori, H. and T. Kobayashi. (2008). Lysenin: a sphingomyelin specific pore-forming toxin. Biochim. Biophys. Acta. 1780(3): 612-618.
Shrestha, N., C.A. Thomas, D. Richtsmeier, A. Bogard, R. Hermann, M. Walker, G. Abatchev, R.J. Brown, and D. Fologea. (2020). Temporary Membrane Permeabilization via the Pore-Forming Toxin Lysenin. Toxins (Basel) 12:.
Yamaji, A., Y. Sekizawa, K. Emoto, H. Sakuraba, K. Inoue, H. Kobayashi and M. Umeda (1998). Lysenin, a novel sphingomyelin-specific binding protein. J. Biol. Chem. 273: 5300-5306.
Examples:
TC#	Name	Organismal Type	Example
1.C.43.1.1	Lysenin of 297 aas and 1 N-terminal TMS, a sphingomyelin-specific pore-forming toxin from earthworms; causes contraction of rat vascular smooth muscle. (Sekizawa et al., 1997; Shogomori and Kobayashi, 2007). Trp-20 is required for cation selective channel assembly (Kwiatkowska et al., 2007). Adenosine phosphates control the activity of lysenin channels inserted into planar lipid membranes with respect to their macroscopic conductance and voltage-induced gating. Addition of ATP, ADP, or AMP decreased the macroscopic conductance of lysenin channels in a concentration-dependent manner, with ATP being the most potent inhibitor and AMP the least (Bryant et al. 2016). lysenin can specifically interact with sphingomyelin, and may confer innate immunity against parasites by attacking the membranes of the parasites to form pores (Pang et al. 2019). Upon binding to sphingomyelin (SM)-containing membranes, lysenin undergoes a series of structural changes promoting the conversion of water-soluble monomers into oligomers, leading to its insertion into the membrane and the 2-step formation of a lytic beta-barrel pore (Kulma et al. 2019). Structural stabilization of the lysenin prepore starts at the site of initial interaction with the lipid membrane and is transmitted to the twisted beta-sheet of the N-terminal domain (Kulma et al. 2019). 3-d structures are available (PDB# 5EC5; 3ZXD; 3ZX7). The beta pore-forming toxins (beta-PFTs) are cytotoxic proteins produced as soluble monomers, which cluster and oligomerize at the membrane of the target host cells. Their initial oligomeric state, the prepore, is not cytotoxic. The beta-PFTs undergo a large structural transition to a second oligomeric state, the pore, which pierces the membrane of the host cell and is cytotoxic. Munguira et al. 2019 described the mechanism by which the rates of formation of the transmembrane pores correlate with the local levels of crowding for the beta-PFT lysenin. Lysenin forms stable pre-pore and pore nonameric rings (Jiao et al. 2021).	Earthworms	Lysenin of Eisenia foetida

1.C.43.1.2	Lysenin 2 or Fetidin of 300 aas and 1 N-terminal TMS. 90% identical to Lysenin 1.		Lysenin 2 of Eisenia fetida

1.C.43.1.3	Lysenin related protein 3 of 300 aas and 1 N-terminal TMS.		Lysenin 3 of Eisenia fetida

1.C.43.1.4	Uncharacterized homologue of Lysenin of 288 aas and 1 N-terminal TMS.		UP of Macrostomum lignano

1.C.43.1.5	Uncharacterized protein of 305 aas and 1 N-terminal TMS.		UP of Sinobacterium caligoides