title: A novel superoxide dismutase with a high isoelectric point in higher plants. expression, regulation, and protein localization.
abstract: Several isoforms of superoxide dismutase (SOD) with a high isoelectric point (pI) have been identified by isoelectric focusing chromatography in protein extracts from Scots pine (Pinus sylvestris) needles. One of these isoforms, a CuZn-SOD with a pI of about 10 and thus denoted hipI-SOD, has been isolated and purified to apparent homogeneity. A cDNA encoding the hipI-SOD protein was cloned and sequenced. Northern hybridization of mRNA isolated from different organs and tissues showed that hipI-SOD has a markedly different pattern of expression compared with chloroplastic and cytosolic SOD. Furthermore, the transcript levels of hipI-SOD and cytosolic SOD were found to respond differently to mechanical wounding, treatment with oxidized glutathione, paraquat, and ozone. Immunogold electron microscopy localized the hipI-SOD in the plasma membrane of sieve cells and the Golgi apparatus of albuminous cells. Moreover, high protein density was also detected in extracellular spaces such as secondary cell wall thickenings of the xylem and sclerenchyma and in intercellular spaces of parenchyma cells.
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Faculty of Forestry, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Karpinska
authors.forename: M
authors.initials: M
authors.lastname: Karlsson
authors.forename: H
authors.initials: H
authors.lastname: Schinkel
authors.forename: S
authors.initials: S
authors.lastname: Streller
authors.forename: K H
authors.initials: KH
authors.lastname: Süss
authors.forename: M
authors.initials: M
authors.lastname: Melzer
authors.forename: G
authors.initials: G
authors.lastname: Wingsle
mesh_terms: D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D001692:Biological Transport; D015152:Blotting, Northern; D002462:Cell Membrane / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D032462:Cycadopsida / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D018076:DNA, Complementary; D018744:DNA, Plant; D015870:Gene Expression; D006056:Golgi Apparatus / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D013482:Superoxide Dismutase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D018744:DNA, Plant; D007527:Isoenzymes; D013482:Superoxide Dismutase