Molecular cloning, characterization and regulation by cadmium of a superoxide dismutase from the ectomycorrhizal fungus Paxillus involutus.
The gene encoding a superoxide dismutase (PiSOD) was cloned by suppressive subtractive hybridization from cDNA library of the ectomycorrhizal fungus, Paxillus involutus, grown under cadmium-stress conditions. The encoded protein was presumed to be localized in the peroxisomes because it contained a C-terminal peroxisomal localization peptide (SKL) and lacked an N-terminal mitochondrial transit peptide. Complementation of an Escherichia coli SOD null strain that is unable to grow in the presence of paraquat or cadmium indicated that cloned Pisod encoded a functional superoxide dismutase. Sensitivity of PiSOD activity to H2O2 but not KCN, and sequence homologies to other SODs strongly suggest that it is a manganese-containing superoxide dismutase. Monitoring PiSOD transcript, immunoreactive polypeptide and superoxide dismutase activity following cadmium stress suggests that the principal level of control is post-translational. This is, to our knowledge, the first insight in the characterization of molecular events that take place in an ectomycorrhizal fungus during exposure to heavy metals.
Jacob
C
C
Université Henri Poincaré Nancy I, Faculté des Sciences, UMR INRA-UHP 1136 Interactions Arbres/Micro-organismes, Vandoeuvre-les-Nancy Cedex, France.
Courbot
M
M
Brun
A
A
Steinman
H M
HM
Jacquot
J P
JP
Botton
B
B
Chalot
M
M
D000363:Agaricales / Q000201:enzymology*; D000595:Amino Acid Sequence; D001483:Base Sequence; D002104:Cadmium / Q000494:pharmacology*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015723:Gene Library; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D013482:Superoxide Dismutase / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics
D018076:DNA, Complementary; D002104:Cadmium; D013482:Superoxide Dismutase