Beticolins, nonpeptidic, polycyclic molecules produced by the phytopathogenic fungus Cercospora beticola, as a new family of ion channel-forming toxins.
Beticolins are toxins produced by Cercospora beticola, a phytopathogenic fungus responsible for the leaf spot disease of sugar beet. They form a family of 20 nonpeptidic compounds (named B0 to B19) that share the same polycyclic skeleton but differ by isomeric configuration (ortho- or para-) and by a variable residue R (bridging two carbons in one of the six cycles). It has been previously shown that B0 assembles itself into a multimeric structure and forms ion channels into planar lipid bilayers (C. Goudet, A.-A. Very, M.-L. Milat, M. Ildefonse, J.-B. Thibaud, H. Sentenac, and J.-P. Blein, Plant J. 14:359-364, 1998). In the present work, we investigate pore formation by three ortho-beticolins, B0, B2, and B4, and their related (i.e., same R) para-isomers, B13, B1, and B3, respectively, using planar lipid bilayers. All beticolins were able to form ion channels with multiple conductance states, although the type of cyclization (ortho- or para-) and residue (R) result in variations of channel conductance and ionic permeability, respectively. Channel formation by beticolins is likely to be involved in the biological activity of these toxins.
Goudet
C
C
Laboratoire de Biochimie et Physiologie Moléculaire des Plantes, CNRS URA 2133/ENSA-M/INRA/UM2, Montpellier, France.
Milat
M L
ML
Sentenac
H
H
Thibaud
J B
JB
D001203:Ascomycota / Q000472:pathogenicity*; D019663:Chenopodiaceae / Q000382:microbiology; D007473:Ion Channels / Q000187:drug effects*; D008051:Lipid Bilayers; D009183:Mycotoxins / Q000737:chemistry* / Q000633:toxicity*; D010935:Plant Diseases / Q000382:microbiology
D007473:Ion Channels; D008051:Lipid Bilayers; D009183:Mycotoxins