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A small family of novel CuZn-superoxide dismutases with high isoelectric points in hybrid aspen

Schinkel, Helga, Hertzberg, Magnus, Wingsle, Gunnar
Planta 2001 v.213 no.2 pp. 272-279
Northern blotting, Pinus sylvestris, Populus tremula, cDNA libraries, complementary DNA, genes, hybrids, isoelectric point, screening, superoxide dismutase
Several CuZn-superoxide dismutases (SODs; EC were cloned from hybrid aspen (Populus tremula L. × tremuloides Michx.). Two of the cloned genes encode representatives of a novel type of CuZn-SOD and we named it HipI-SOD because of its high isoelectric point (≥9). The SODs were cloned by screening a cDNA library with a probe based on a Scots pine (Pinus sylvestris L.) CuZn-SOD that is predominantly located extracellularly. The expression pattern of HipI-SOD was examined using a Northern blot technique and compared with the expression patterns of cytosolic and chloroplastic SODs. Distinct expression patterns were observed for the three types of CuZn-SOD, with HipI-SODs showing strong expression in apical tissues. Southern blots as well as protein analysis suggest that these novel HipI-SODs belong to a small gene family, one member of which might be monomeric.