title: Superoxide dismutase: a differentiation protein expressed in Uromyces germlings during early appressorium development.
abstract: Germlings of the bean rust fungus Uromyces appendiculatus detect penetration sites on the surface of the host leaf by thigmosensing topographical features. Within 2-4 min after the apex of a urediospore germ tube encounters the cuticular lip of a stomate, the germling ceases polarized growth and begins to swell over the aperture. The mechanism by which the cells detect topographical signals is not understood; however, previous experiments indicated that the initiation process does not involve de novo gene expression. In order to detect posttranslational modifications, the protein profiles of induced and noninduced germlings were compared at the earliest stages of appressorium formation, and a 21-kDa differentiation protein was identified by a shift in isoelectric point. The N-terminal amino acid sequence exhibited homology with superoxide dismutase (SOD), and antibodies to a synthetic peptide fragment of the respective sequence recognized cooper/zinc isozymes of SOD in electroblots of native gels. Electroelution of the active enzyme bands and separation by SDS-PAGE indicated that the 21-kDa protein is a component of a tetrameric 85-kDa SOD.
authors.affiliation: Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Lamboy
authors.forename: R C
authors.initials: RC
authors.lastname: Staples
authors.forename: H C
authors.initials: HC
authors.lastname: Hoch
mesh_terms: D000595:Amino Acid Sequence; D000906:Antibodies; D000911:Antibodies, Monoclonal; D001487:Basidiomycota / Q000201:enzymology / Q000254:growth & development*; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D007525:Isoelectric Focusing; D007527:Isoenzymes / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D013172:Spores, Fungal; D013482:Superoxide Dismutase / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D000906:Antibodies; D000911:Antibodies, Monoclonal; D007527:Isoenzymes; D010446:Peptide Fragments; D013482:Superoxide Dismutase