TY - JOUR
T1 - Differential Effect of Membrane Composition on the Pore-Forming Ability of Four Different Sea Anemone Actinoporins
AU - García-Linares, Sara
AU - Rivera-De-Torre, Esperanza
AU - Morante, Koldo
AU - Tsumoto, Kouhei
AU - Caaveiro, Jose M.M.
AU - Gavilanes, José G.
AU - Slotte, J. Peter
AU - Martínez-Del-Pozo, Álvaro
N1 - Funding Information:
This work was funded by Grant BFU2012-32404 from the Spanish Ministerio de Economıa y Competitividad e Innovación, by grants from the Academy of Finland, the Sigrid Juselius Foundation, the Ella and Georg Ehrnrooth Foundation, and the Magnus Ehrnrooth Foundation to J.P.S., by the Platform for Drug Discovery, Informatics and Structural Life Science from the Ministry of Education, Culture, Sports, Science and Technology of Japan, and by Grants-in-Aid for Scientific Research C (16H02420 and 15K06962) from the Japan Society for the Promotion of Science. A FPU fellowship was granted to S.G.-L. and a UCM fellowship to E.R.-d.-T. We thank Mia Åstrand for her help in performing some of the experiments made with dihydro-SMs. Equinatoxin II was a kind gift from Drs. TomažŠvigelj and Gregor Anderluh (Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia).
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/12/6
Y1 - 2016/12/6
N2 - Sea anemone actinoporins constitute a protein family of multigene pore-forming toxins (PFT). Equinatoxin II (EqtII), fragaceatoxin C (FraC), and sticholysins I and II (StnI and StnII, respectively), produced by three different sea anemone species, are the only actinoporins whose molecular structures have been studied in depth. These four proteins show high sequence identities and practically coincident three-dimensional structures. However, their pore-forming activity can be quite different depending on the model lipid system employed, a feature that has not been systematically studied before. Therefore, the aim of this work was to evaluate and compare the influence of several distinct membrane conditions on their particular pore-forming behavior. Using a complex model membrane system, such as sheep erythrocytes, StnII showed hemolytic activity much higher than those of the other three actinoporins studied. In lipid model systems, pore-forming ability when assayed against 4:1 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/sphingomyelin (SM) vesicles, with the membrane binding being the rate-limiting step, decreased in the following order: StnI > StnII > EqtII > FraC. When using 1:1:1 DOPC/SM/cholesterol LUVs, the presence of Chol not only enhanced membrane binding affinities by ∼2 orders of magnitude but also revealed how StnII was much faster than the other three actinoporins in producing calcein release. This ability agrees with the proposal that explains this behavior in terms of their high sequence variability along their first 30 N-terminal residues. The influence of interfacial hydrogen bonding in SM- or dihydro-SM-containing bilayers was also shown to be a generalized feature of the four actinoporins studied. It is finally hypothesized that this observed variable ability could be explained as a consequence of their distinct specificities and/or membrane binding affinities. Eventually, this behavior can be modulated by the nature of their natural target membranes or the interaction with not yet characterized isotoxin forms from the same sea anemone species.
AB - Sea anemone actinoporins constitute a protein family of multigene pore-forming toxins (PFT). Equinatoxin II (EqtII), fragaceatoxin C (FraC), and sticholysins I and II (StnI and StnII, respectively), produced by three different sea anemone species, are the only actinoporins whose molecular structures have been studied in depth. These four proteins show high sequence identities and practically coincident three-dimensional structures. However, their pore-forming activity can be quite different depending on the model lipid system employed, a feature that has not been systematically studied before. Therefore, the aim of this work was to evaluate and compare the influence of several distinct membrane conditions on their particular pore-forming behavior. Using a complex model membrane system, such as sheep erythrocytes, StnII showed hemolytic activity much higher than those of the other three actinoporins studied. In lipid model systems, pore-forming ability when assayed against 4:1 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/sphingomyelin (SM) vesicles, with the membrane binding being the rate-limiting step, decreased in the following order: StnI > StnII > EqtII > FraC. When using 1:1:1 DOPC/SM/cholesterol LUVs, the presence of Chol not only enhanced membrane binding affinities by ∼2 orders of magnitude but also revealed how StnII was much faster than the other three actinoporins in producing calcein release. This ability agrees with the proposal that explains this behavior in terms of their high sequence variability along their first 30 N-terminal residues. The influence of interfacial hydrogen bonding in SM- or dihydro-SM-containing bilayers was also shown to be a generalized feature of the four actinoporins studied. It is finally hypothesized that this observed variable ability could be explained as a consequence of their distinct specificities and/or membrane binding affinities. Eventually, this behavior can be modulated by the nature of their natural target membranes or the interaction with not yet characterized isotoxin forms from the same sea anemone species.
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U2 - 10.1021/acs.biochem.6b01007
DO - 10.1021/acs.biochem.6b01007
M3 - Article
C2 - 27933793
AN - SCOPUS:85002930502
SN - 0006-2960
VL - 55
SP - 6630
EP - 6641
JO - Biochemistry
JF - Biochemistry
IS - 48
ER -