Flammutoxin, a cytolysin from the edible mushroom Flammulina velutipes, forms two different types of voltage-gated channels in lipid bilayer membranes.
Flammutoxin, a cytolysin from the edible mushroom Flammulina velutipes, forms two different types of voltage-gated channels in lipid bilayer membranes.
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DOI：
10.1016/s0005-2736(00)00240-6
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发表时间：
2000-08
期刊：
影响因子：
--
通讯作者：
G. Tadjibaeva;R. Sabirov;T. Tomita
中科院分区：
文献类型：
--
作者：
G. Tadjibaeva;R. Sabirov;T. Tomita
Flammutoxin, a 31-kDa cardiotoxic and cytolytic protein from the edible mushroom Flammulina velutipes, has been shown to assemble into a pore-forming annular oligomer with outer and inner diameters of 10 and 5 nm on the target cells [Tomita et al., Biochem. J. 333 (1998) 129–137]. Here we studied electrophysiological properties of flammutoxin channels using planar lipid bilayer technique, and found that flammutoxin formed two types of moderately cation-selective, voltage-gated channels with smaller and larger current amplitudes (1–4.5 pA and 20–30 pA, respectively, at 20 mV) in the lipid bilayers composed of phospholipid and cholesterol. The larger-conductance single channel showed the properties of a wide water-filled pore such as a linear relationship between channel conductance and salt concentration of the bathing solution. The functional diameter of the larger-conductance channel was estimated to be 4–5 nm by measuring the current conductance in the presence of polyethylene glycols of various sizes. In contrast, the smaller-conductance single channels showed a non-linear current to voltage curve and a saturating conductance to increasing salt concentration. These results suggest that the larger-conductance channel of flammutoxin corresponds to the hemolytic pore complex, while the smaller-conductance channel may reflect the intermediate state(s) of the assembling toxin.
