Physiologische und cytologische Aspekte der Wirkung des Toxins von Corynebacterium michiganense pv. michiganense (Smith) Jensen auf die Wirtspflanze

The anion channel protein from Clavibacter michiganense ssp. nebraskense (Schürholz, Th. et al. 1991, J. Membrane Biol. 123: 1-8) was analyzed at different concentrations of KCl and KF. At 0.8 M KCl the conductance G(V(m)) increases exponentially from 21 pS at 50 mV up to 53 pS at V(m) = 200 mV, 20 degrees C. The concentration dependence of G(V(m)) corresponds to a Michaelis-Menten type saturation function at all membrane voltage values applied (0-200 mV). The anion concentration K(0.5), where G(V(m)) has its half-maximum value, increases from 0.12 M at 50 mV to 0.24 M at 175 mV for channels in a soybean phospholipid bilayer. The voltage dependence of the single channel conductance, which is different for charged and neutral lipid bilayers, can be described either by a two-state flicker (2SF) model and the Nernst-Planck continuum theory, or by a two barrier, one-site (2B1S) model with asymmetric barriers. The increase in the number of open channels after a voltage jump from 50 mV to 150 mV has a time constant of 0.8 s. The changes of the single-channel conductance are much faster (<1 ms). The electric part of the gating process is characterized by the (reversible) molar electrical work DeltaG(theta) (el) = rhoZ(g)FV(m) approximately -1.3 RT, which corresponds to the movement of one charge of the gating charge number Z(g) = 1 across the fraction rho = DeltaV(m)/V(m) = 0.15 of the membrane voltage V(m) = 200 mV. Unlike with chloride, the single channel conductance of fluoride has a maximum at about 150 mV in the presence of the buffer PIPES (>/=5 mM, pH 6.8) with K(0.5) approximately 1 M. It is shown that the decrease in conductance is due to a blocking of the channel by the PIPES anion. In summary, the results indicate that the anion transport by the Clavibacter anion channel (CAC) does not require a voltage dependent conformation change of the CAC.

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“…Comparing Eqs. 5 Eq. 6 was used to describe the current data, which were measured in the presence ofKCl-gradients.…”

Section: Resultsmentioning

confidence: 99%

“…(2)) or glycolipids (C. rathayi; (3)). The isolated polysaccharides cause wilting in plant assays (4) and a degeneration of chloroplasts (5). However, such an effect can be attributed to water stress rather than to a discrete action of the polysaccharide on the chloroplasts and its membrane.…”

Section: Introductionmentioning

confidence: 99%

Single-channel analysis of the anion channel-forming protein from the plant pathogenic bacterium Clavibacter michiganense ssp. nebraskense

Schürholz¹,

Dloczik²,

Neumann³

1993

Biophysical Journal

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“…The mode of action of the elicitors of plant cell necrobiosis greatly resembles that described for microbial phytotoxins (YODER 1980, KRAEMER andLEISTNER 1986). Both agent classes more or less induce cell and vein necrosis, electrolyte leakage, and respiration increase in the impaired leaf tissue.…”

Section: Discussionmentioning

confidence: 79%

“…Top efficacy in conferring pathovirulence to plant pathogens should be ascribed to fungal suppressors of phytoalexin production (OKU 1980, BUSHNELL and ROWELL 198 l), the detoxification of phytoalexins by the pathogen (DELSERONE and VAN ETTEN 1987, ZHANG andSMITH 1983), and to the wide array of fungal metabolites with necrobiotic activities toward host plant cells that generally interfere with the vitality status of the living cell. Among these metabolites the favorite topics of research are the bulk of microbial phytotoxins that may confer pathosism to the producing pathogen or increase at least its virulence by inflicting damage on host plant cell organelles (YODER 1980, KRAEMER andLEISTNER 1986). In respect of the crucial role the living and functional parenchyma cell plays in the resistance reaction of timber it appears inevitable to screen the wood-decay fungi of all ecological categories for the production of elicitors of plant cell necrobiosis in the light of their known degree of pathosism.…”

mentioning

confidence: 99%

Invasion of wood by basidiomycetous fungi. V. The role of fungal elicitors of plant cell necrobiosis in the expression of pathovirulence and kratovirulence

Gramss

1989

J. Basic Microbiol.

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Within the intact tree the live cell is the exclusive carrier of phytopathological defence reactions against microbial attack. In a comprehensive search for fungal virulence factors capable of weakening the living tissues in timber, 48 species of wood-destroying basidiomycetous fungi (WBF)') with known degree of pathosism and the corresponding degree of saprophytism were grown on liquid still cultures. Droplets of the filtered culture fluids were then applied to pin-prick wounds in the interveinal area of leaves from several tree and one herb species, Within 48 hours of development circular spots of brown necrotic tissue expanded around the pin pricks to indicate and approximately quantify the presence of fungal elicitors of necrobiosis. The resulting necrobiosis index was, with certain exceptions, not correlated with the antimicrobial potency (kratovirulence) of the fungus, its pathosism against standing timber, and the activity of exoenzymes in white-rot fungi. The necrobiosis index was, in part, positively correlated with the activity of those brown-rot fungi that dispose of an effective wood-decay capacity. Characteristic of the fungal species as well as of the fungal strain the necrobiosis index ranked from 0 to 1,421.2 mmz necrotic net area per 300 pin pricks but there was no fungus to be unable of eliciting browning in at least a few of the leaf species. The most severe necrosis was permanently observed on leaves of several generally oversusceptible tree species rather than on the notorious host species of the test fungus. It is therefore concluded that the elicitors of plant cell necrobiosis in WBF are predominantly host-nonspecific stress factors that may sometimes increase fungal pathovirulence. Their purification should help characterize their action as phytotoxic, necrobiotic, enzymatic, or even antimicrobial.

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“…michiganense ) or glycolipids ( Clavibacter rahtayi ) . It is established that the isolated polysaccharides cause wilting in plant assays and degeneration of chloroplasts, which is discussed in terms of water stress. , However, the presence of polysaccharides does not explain the discrete action on chloroplasts and their membranes. Schürholz et al , systematically searched for toxic activities excreted into the culture medium of C. michiganense ssp.…”

Section: Introductionmentioning

confidence: 99%

Membrane Activity of an Anion Channel from Clavibacter michiganense ssp. nebraskense

et al. 2001

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The spontaneous insertion of an anion selective protein channel (Clavibacter anion channel, CAC) present in the culture fluid of Clavibacter michiganense ssp. nebraskense was monitored by using solid supported lipid membranes (SSMs) composed of the positively charged lipid N,N-dimethyl-N,N-dioctadecylammonium bromide immobilized via electrostatic interaction on a negatively charged monolayer of 3-mercaptopropionic acid chemisorbed on gold. By means of impedance spectroscopy, conductance changes of the immobilized lipid membranes were sensitively detected after adding the culture fluid of the bacteria to the SSMs. Variation in the dc potential revealed that CAC exhibits its unique voltage dependence in SSMs described by an exponential function in accordance to previous results obtained from patch clamp measurements. Protease treatment and the addition of an anion selective channel inhibitor diminished the increased conductivity of the membrane after CAC addition clearly indicating that the increased conductivity is attributed to the specific insertion of the channel protein. The results demonstrate the potential of this kind of electrostatically attached solid supported membrane combined with impedance spectroscopy allowing one to monitor and characterize water-soluble spontaneously inserting channel forming bacterial toxins.

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Physiologische und cytologische Aspekte der Wirkung des Toxins von Corynebacterium michiganense pv. michiganense (Smith) Jensen auf die Wirtspflanze

Cited by 14 publications

References 14 publications

Single-channel analysis of the anion channel-forming protein from the plant pathogenic bacterium Clavibacter michiganense ssp. nebraskense

Single-channel analysis of the anion channel-forming protein from the plant pathogenic bacterium Clavibacter michiganense ssp. nebraskense

Invasion of wood by basidiomycetous fungi. V. The role of fungal elicitors of plant cell necrobiosis in the expression of pathovirulence and kratovirulence

Membrane Activity of an Anion Channel from Clavibacter michiganense ssp. nebraskense

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