Voltage‐dependent and multi‐state ionic channels induced by trichorzianines, anti‐fungal peptides related to alamethicin

Molle, Gérard; Duclohier, H.; Spach, G.

doi:10.1016/0014-5793(87)80449-0

Cited by 40 publications

(22 citation statements)

References 12 publications

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“…the trichorzianines (19 residues, Molle et al 1987;Duclohier et al 1989). Zrv-IIB resembles alamethicin in that its macroscopic I-V relationship is asymmetric, with channel activation occurring at cis positive potentials .…”

Section: Kn±i=fn~i/rn Synthetic Alamethicin Analoguesmentioning

confidence: 99%

Alamethicin and related peptaibols ? model ion channels

1993

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Peptaibols are considered as models of those ion channels which consist of a bundle of transbilayer helices surrounding a central pore. X-Ray diffraction and NMR studies have yielded high resolution structures for several peptaibols. In conjunction with other spectroscopic investigations and molecular dynamics simulations, these studies suggest that peptaibols form proline-kinked alpha-helices, and that there may be "hinge-bending" movement of the helix in the region of the central proline residue. The amphipathicity of peptaibol helices is analyzed in relation to their channel-forming properties. Studies of the interactions of peptaibols with lipid bilayers suggest that they are helical when in a membrane-like environment, and that the helix orientation relative to the bilayer is sensitive to the peptaibol:lipid ratio, and to the degree of hydration of the bilayer. Electrical studies reveal that many peptaibols form multiple-conductance level channels in a voltage-dependent fashion. Analysis of conductance levels provides support for the "barrel stave" model of channel formation, whereby different conductance levels correspond to different numbers of monomers in a helix bundle. Alternative models for voltage-activation are discussed, and the roles of molecular dipoles and of hinge-bending in this process are considered. Two molecular models for an N = 6 bundle of alamethicin helices are presented and their electrostatic properties analyzed. The relevance of studies of peptaibols to channel and transport proteins in general is considered.

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Section: Kn±i=fn~i/rn Synthetic Alamethicin Analoguesmentioning

confidence: 99%

Alamethicin and related peptaibols ? model ion channels

1993

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“…They have been shown to interact with phospholipid bilayers and to increase their permeability for concentrations ranging between 10 Ϫ6 and 10 Ϫ7 M (10, 18). They form voltage-gated ion channels in planar bilayers at 10 Ϫ8 M (22). When combined with hydrolytic enzymes, they produce synergistic mixtures with strong inhibitory activity on the growth of many pathogenic fungi (20,24).…”

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confidence: 99%

Cell wall synthesis is a major target of mycoparasitic antagonism by Trichoderma harzianum

et al. 1996

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We have investigated the molecular basis for the reported synergism between peptaibols and cell wall hydrolytic enzymes in the antagonism of phytopathogenic fungi by Trichoderma harzianum. ␤-Glucan synthase activity on isolated plasma membranes of Botrytis cinerea was inhibited in vitro by the peptaibols trichorzianin TA and TB, and this inhibition was reversed by the addition of phosphatidylcholine. ␤-Glucan synthesis in vivo, assayed by the incorporation of [2-3 H]glucose into cell wall material, was inhibited by the presence of peptaibols, and this inhibition was synergistic with exogenously added T. harzianum ␤-1,3-glucanase. This synergism is therefore explained by an inhibition of the membrane-bound ␤-1,3-glucan synthase of the host by the peptaibols, which inhibit the resynthesis of cell wall ␤-glucans, sustain the disruptive action of ␤-glucanases, and all together enhance the fungicidal activity. Therefore, we have identified cell wall turnover as a major target of mycoparasitic antagonism.The soil fungus Trichoderma harzianum is active against a range of economically important aerial and soilborne plant pathogens and is successfully used as a biopesticide in greenhouse and field applications (4, 23). The antagonistic mechanism of T. harzianum is a complex process involving chemotropism (5), lectin-mediated recognition (15-17), and formation of trapping and penetration structures (7,8). This process is further supported by the secretion of extracellular enzymes such as chitinases (3,6,14), ␤-glucanases (13, 19, 21), and proteinases (11) as well as secondary metabolites (1, 2, 12). However, the fungicidal mechanism of T. harzianum is so far unknown. A key to understanding this mechanism of antagonism is the recently found synergism between hydrolytic enzymes and membraneaffecting antibiotics such as peptaibols (20,24) which lowers the active concentrations of the two types of compounds to the level observed in vivo. Peptaibols are linear amphipathic and antibiotic 7-to 20-residue peptides, mainly produced by fungi of the genus Trichoderma. They are structurally characterized by an acylated N-terminal residue, a C-terminal amino-alcohol (tryptophanol or phenylalaninol), and a high content in ␣-aminoisobutyric acid. They have been shown to interact with phospholipid bilayers and to increase their permeability for concentrations ranging between 10 Ϫ6 and 10 Ϫ7 M (10, 18). They form voltage-gated ion channels in planar bilayers at 10 Ϫ8 M (22). When combined with hydrolytic enzymes, they produce synergistic mixtures with strong inhibitory activity on the growth of many pathogenic fungi (20, 24). We therefore speculated that the synergism of peptaibols with chitinases and ␤-glucanases could be due to an interference with cell wall synthesis associated with the plasma membrane.We have first tested this hypothesis in vitro by using trichorzianins TA and TB from T. harzianum and ␤-glucan synthase from three different fungi: Botrytis cinerea, T. harzianum, and Saccharomyces cerevisiae. Trichorzianin TA is a micro...

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“…Parallel formation of hydrolytic enzymes and 19-residue antifungal trichorzianins A and B by the potent mycoparasite Trichoderma atroviride 7) is triggered in the presence of cell walls of plant-pathogenic fungi [106]. Trichorzianins have previously been shown to form voltage-gated ion channels in planar lipid bilayers [107] and to modify the membrane permeability of liposomes, and they are active against Rhizoctonia solani and Phythophthora cactorum [108]. Based on these findings, a model of how peptaibiotics such as trichorzianins and hydrolases interact synergistically was proposed.…”

Section: Discussionmentioning

confidence: 99%

Screening the Biosphere: The Fungicolous Fungus Trichoderma phellinicola, a Prolific Source of Hypophellins, New 17‐, 18‐, 19‐, and 20‐Residue Peptaibiotics

Röhrich

Iversen

Jaklitsch

et al. 2013

Chemistry & Biodiversity

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To investigate the significance of antibiotics for the producing organism(s) in the natural habitat, we screened a specimen of the fungicolous fungus Trichoderma phellinicola (syn. Hypocrea phellinicola) growing on its natural host Phellinus ferruginosus. Results revealed that a particular group of non-ribosomal antibiotic polypeptides, peptaibiotics, which contain the non-proteinogenic marker amino acid, α-aminoisobutyric acid, was biosynthesized in the natural habitat by the fungicolous producer and, consequently, released into the host. By means of liquid chromatography coupled to electrospray high-resolution time-of-flight mass spectrometry, we detected ten 20-residue peptaibols in the specimen. Sequences of peptaibiotics found in vivo were independently confirmed by analyzing the peptaibiome of an agar plate culture of T. phellinicola CBS 119283 (ex-type) grown under laboratory conditions. Notably, this strain could be identified as a potent producer of 39 new 17-, 18-, and 19-residue peptaibiotics, which display the same building scheme as the 20-residue peptaibols found in the specimen. Two of the 19-residue peptaibols are tentatively assigned to carry tyrosinol, a novel C-terminal residue, as deduced from high-resolution tandem mass-spectrometry data. For the new peptaibiotics produced by T. phellinicola, the name ‘hypophellin(s)’, based on the teleomorph name, is introduced.

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Voltage‐dependent and multi‐state ionic channels induced by trichorzianines, anti‐fungal peptides related to alamethicin

Cited by 40 publications

References 12 publications

Alamethicin and related peptaibols ? model ion channels

Alamethicin and related peptaibols ? model ion channels

Cell wall synthesis is a major target of mycoparasitic antagonism by Trichoderma harzianum

Screening the Biosphere: The Fungicolous Fungus Trichoderma phellinicola, a Prolific Source of Hypophellins, New 17‐, 18‐, 19‐, and 20‐Residue Peptaibiotics

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