Helminthosporium maydis T toxin decreased calcium transport into mitochondria of susceptible corn
The effects of purified Helminthosporium maydis T (HmT) toxin on active Ca/sup 2 +/ transport into isolated mitochondria and microsomal vesicles were compared for a susceptible (T) and a resistant (N) strain of corn (Zea mays). ATP, malate, NADH, or succinate could drive /sup 45/Ca/sup 2 +/ transport into mitochondria of corn roots. Ca/sup 2 +/ uptake was dependent on the proton electrochemical gradient generated by the redox substrates or the reversible ATP synthetase, as oligomycin inhibited ATP-driven CA/sup 2 +/ uptake while KCN inhibited transport driven by the redox substrates. Purified native HmT toxin completely inhibited Ca/sup 2 +/ transport into T mitochondria at 5 to 10 nanograms per milliliter while transport into N mitochondria was decreased slightly by 100 nanograms per milliliter toxin. Malate-driven Ca/sup 2 +/ transport in T mitochondria was frequently more inhibited by 5 nanograms per milliliter toxin than succinate or ATP-driven Ca/sup 2 +/ uptake. However, ATP-dependent Ca/sup 2 +/ uptake into microsomal vesicles from either N or T corn was not inhibited by 100 nanograms per milliliter toxin. Similarly, toxin had no effect on proton gradient formation ((/sup 14/C)methylamine accumulation) in microsomal vesicles. These results show that mitochondrial and not microsomal membrane is a primary site of HmT toxin action. HmT toxin may inhibit formation of or dissipate the electrochemical proton gradient generated by substrate-driven electron transport or the mitochondrial ATPase, after interacting with a component(s) of the mitochondrial membrane in susceptible corn.
- Research Organization:
- Univ. of Kansas, Lawrence, KS (United States)
- DOE Contract Number:
- AS05-82ER13015
- OSTI ID:
- 7096930
- Journal Information:
- Plant Physiol.; (United States), Vol. 74:4
- Country of Publication:
- United States
- Language:
- English
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CALCIUM
MINERAL CYCLING
UPTAKE
FUNGI
BIOLOGICAL EFFECTS
MAIZE
MITOCHONDRIA
ATP-ASE
CARBON 14
ENZYME ACTIVITY
FUNGAL DISEASES
LABELLING
TRACER TECHNIQUES
ACID ANHYDRASES
ALKALINE EARTH METALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON ISOTOPES
CELL CONSTITUENTS
CEREALS
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ELEMENTS
ENZYMES
EVEN-EVEN NUCLEI
GRAMINEAE
GRASS
HYDROLASES
INFECTIOUS DISEASES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
METALS
NUCLEI
ORGANOIDS
PHOSPHOHYDROLASES
PLANTS
RADIOISOTOPES
YEARS LIVING RADIOISOTOPES
550901* - Pathology- Tracer Techniques