Title: CYTOSOLIC AND EXTRACELLULAR CU ZN SUPEROXIDE DISMUTASES FROM LYSIPHLEBUS TESTACEIPES Authors
|Weathersbee Iii, Albert|
Submitted to: Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: June 25, 2005
Publication Date: December 15, 2005
Citation: Weathersbee III, A.A., Boykin, L.M., Katsar, C.S. 2005. Cytosolic and extracellular cu zn superoxide dismutases from lysiphlebus testaceipes. Entomological Society of America Annual Meeting. December 15, 2005. Technical Abstract: The superoxide dismutases (SODs) are antioxidant enzymes that protect aerobic organisms from the damaging effects of reactive oxygen species (ROS). Within the Metazoa, there are three recognized SOD families with two possible arrangements of metal ligands, either Mn, or Cu and Zn ions, at the active site of the molecule. The Mn form (SOD2) of the enzyme is localized within the mitochondrial matrix of cells and its structure differs greatly from the Cu, Zn SODs discussed here. The Cu, Zn SODs exist either as a cytosolic form (SOD1) within the cell or an extracellular form (SOD3) that is secreted from the cell. We have cloned and sequenced cDNAs encoding all three forms of SOD from the aphid parasitoid Lysiphlebus testaceipes. Until recently, only representatives of the SOD1 and SOD2 families had been described in insects. Evidence for an extracellular Cu, Zn SOD3 in insects was first reported in 2004. For parasites, such as L. testaceipes, these enzymes can provide additional protection against oxygen-mediated defense mechanisms of its host; and therefore, may be considered virulence factors. The protein for L. testaceipes SOD1 is 151 aa long, while the protein precursor for L. testaceipes SOD3 is 172 aa long and contains a 16 aa secretory signal that is cleaved from the amino terminal to yield the mature protein. We provide homology models of SOD1 and SOD3 from L. testaceipes that demonstrates remarkable conservation of enzyme structure among members of the Cu, Zn SOD gene families.