| dc.description | Sticholysin I (St1) and II (St2) are polypeptides isolated
from the Caribbean sea anemone Stichodactyla
Helianthus, with a molecular mass of 19401 and
19290 Da, with hemolytic and pore-forming properties
in membranes (LANIO et al., 2000). It has been
previously determined that the activity of membrane
pore formation is related to the N-terminal insertion
in the bilayer and lipid phase coexistence must play a
role too (ROS et al., 2013). As PFTs, both toxins are
considered to have potential appliance in parasitic
and tumor diseases (MART??NEZ et al., 2007). In this
work, we have investigated GUVs composed of nonoxidized
POPC and POPC hydroperoxide (POPC-OOH)
interacting with ST1 and ST2 by optical microscopy.
The results did not reveal a significant PFT-membrane
interaction such that no membrane destabilization
was observed over incubation time of 20 min. On the
other hand, when GUVs were made of mixtures of
POPC or POPC-OOH and Sphingomyellin (SM), optical
contrast fading was noticed indicating an increase in
lipid bilayer permeability due to pore formation. Of
note, neither micron-sized pores were observed nor
membrane disruption. Further, the results also pointed
out vesicles composed of oxidized lipids and SM have
a much faster pore forming capacity. Therefore, our
results thus suggest that membranes containing -OOH
and SM promote the insertion of toxins due to their
great fluidity, facilitating the insertion of the TFPs and
their differentiation, leading to the formation of pores. | |
