Potent anti-tumor effects of an active site mutant of human manganese-superoxide dismutase. Evolutionary conservation of product inhibition.
Mn-SOD serves as the primary cellular defense against oxidative damage by converting superoxide radicals (O(2)(-)) to O(2) and H(2)O(2). A unique characteristic of this mitochondrial anti-oxidant enzyme is the conservation from bacteria to man of a rapidly formed product inhibited state. Using site-directed mutagenesis, we have generated an active site mutant (H30N) of human Mn-SOD, which exhibits significantly reduced product inhibition and increased enzymatic efficiency. Overexpression of the H30N enzyme causes anti-proliferative effects in vitro and anti-tumor effects in vivo. Our results provide a teleological basis for the phylogenetically invariant nature of position His-30 and the evolutionary conservation of product inhibition. These data also provide more direct intracellular evidence for the signaling role associated with H(2)O(2).
Davis
Christopher A
CA
Department of Neuroscience, University of Florida Shands Cancer Center, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
Hearn
Amy S
AS
Fletcher
Bradley
B
Bickford
Justin
J
Garcia
Jorge E
JE
Leveque
Vincent
V
Melendez
J Andres
JA
Silverman
David N
DN
Zucali
James
J
Agarwal
Anupam
A
Nick
Harry S
HS
D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001665:Binding Sites; D015152:Blotting, Northern; D002374:Catalase / Q000378:metabolism; D002384:Catalysis; D002455:Cell Division; D002460:Cell Line; D018360:Crystallography, X-Ray; D018076:DNA, Complementary / Q000378:metabolism; D019143:Evolution, Molecular; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D006639:Histidine / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015151:Immunoblotting; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D016513:Mice, SCID; D008928:Mitochondria / Q000378:metabolism; D008956:Models, Chemical; D008957:Models, Genetic; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010100:Oxygen / Q000378:metabolism*; D010802:Phylogeny; D010957:Plasmids / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000235:genetics*; D013997:Time Factors; D014162:Transfection
D000975:Antioxidants; D018076:DNA, Complementary; D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D006639:Histidine; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D010100:Oxygen