title: Herbicide safener-binding protein of maize. Purification, cloning, and expression of an encoding cDNA.
abstract: Dichloroacetamide safeners protect maize (Zea mays L.) against injury from chloroacetanilide and thiocarbamate herbicides. Etiolated maize seedlings have a high-affinity cytosolic-binding site for the safener [3H](R,S)-3-dichloroacetyl-2,2,5-trimethyl-1, 3-oxazol-idine ([3H]Saf), and this safener-binding activity (SafBA) is competitively inhibited by the herbicides. The safener-binding protein (SafBP), purified to homogeneity, has a relative molecular weight of 39,000, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and an isoelectric point of 5.5. Antiserum raised against purified SafBP specifically recognizes a 39-kD protein in etiolated maize and sorghum (Sorghum bicolor L.), which have SafBA, but not in etiolated wheat (Triticum aestivum L.), oat (Avena sativa L.), barley (Hordeum vulgare L.), tobacco (Nicotiana tabacum L.), or Arabidopsis, which lack SafBA. SafBP is most abundant in the coleoptile and scarcest in the leaves, consistent with the distribution of SafBA. SBP1, a cDNA encoding SafBP, was cloned using polymerase chain reaction primers based on purified proteolytic peptides. Extracts of Escherichia coli cells expressing SBP1 have strong [3H]Saf binding, which, like binding to the native maize protein, is competitively inhibited by the safener dichlormid and the herbicides S-ethyl dipropylthiocarbamate, alachlor, and metolachlor. SBP1 is predicted to encode a phenolic O-methyltransferase, but SafBP does not O-methylate catechol or caffeic acid. The acquisition of its encoding gene opens experimental approaches for the evaluation of the role of SafBP in response to the relevant safeners and herbicides.
authors.affiliation: Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Scott-Craig
authors.forename: J E
authors.initials: JE
authors.lastname: Casida
authors.forename: L
authors.initials: L
authors.lastname: Poduje
authors.forename: J D
authors.initials: JD
authors.lastname: Walton
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics; D006540:Herbicides / Q000378:metabolism* / Q000633:toxicity; D008969:Molecular Sequence Data; D010080:Oxazoles / Q000378:metabolism*; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification; D011485:Protein Binding / Q000235:genetics; D017422:Sequence Analysis, DNA; D003313:Zea mays / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D006540:Herbicides; D010080:Oxazoles; D010940:Plant Proteins; C111438:SBP1 protein, Zea mays; C092143:3-(dichloroacetyl)-2,2,5-trimethyl-1,3-oxazolidine