Unusual location and characterization of Cu/Zn-containing superoxide dismutase from filamentous fungus Humicola lutea.
The present study aims to provide new information about the unusual location of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) in lower eukaryotes such as filamentous fungi. Humicola lutea, a high producer of SOD was used as a model system. Subcellular fractions [cytosol, mitochondrial matrix, and intermembrane space (IMS)] were isolated and tested for purity using activity measurements of typical marker enzymes. Evidence, based on electrophoretic mobility, sensitivity to KCN and H(2)O(2) and immunoblot analysis supports the existence of Cu/Zn-SOD in mitochondrial IMS, and the Mn-SOD in the matrix. Enzyme activity is almost equally partitioned between both the compartments, thus suggesting that the intermembrane space could be one of the major sites of exposure to superoxide anion radicals. The mitochondrial Cu/Zn-SOD was purified and compared with the previously published cytosolic enzyme. They have identical molecular mass, cyanide- and H(2)O(2)-sensitivity, N-terminal amino acid sequence, glycosylation sites and carbohydrate composition. The H. lutea mitochondrial Cu/Zn-SOD is the first identified naturally glycosylated enzyme, isolated from IMS. These findings suggest that the same Cu/Zn-SOD exists in both the mitochondrial IMS and cytosol.
Krumova
Ekaterina
E
The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria.
Dolashki
Alexander
A
Pashova
Svetlana
S
Dolashka-Angelova
Pavlina
P
Stevanovic
Stefan
S
Hristova
Rumyana
R
Stefanova
Lilyana
L
Voelter
Wolfgang
W
Angelova
Maria
M
D001203:Ascomycota / Q000737:chemistry* / Q000201:enzymology*; D015153:Blotting, Western; D002458:Cell Fractionation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006031:Glycosylation; D008928:Mitochondria / Q000737:chemistry* / Q000201:enzymology*; D051336:Mitochondrial Membranes / Q000737:chemistry* / Q000201:enzymology*; D008970:Molecular Weight; D011190:Potassium Cyanide / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification