title: CsV03-3 is a member of a novel gene family from citrus that encodes a protein with DNA binding activity and whose expression is responsive to defense signals and abiotic stress.
abstract: We have identified a novel gene designated CsV03-3 from Citrus sinensis (L.) Osbeck that encodes a 50 amino acid polypeptide with a predicted molecular mass of 5.4kDa and a pI of 3.7. CsV03-3 expression is up-regulated by application of methyl jasmonate, salicylic acid, and abscisic acid as well as by abiotic stress and insect herbivory. CsV03-3 belongs to a small gene family consisting of at least three other closely related members (CsV03-1, CsV03-2, and CsV03-4) whose expression is also responsive to phytohormone application and abiotic stress. Sequence similarity searches of the public databases were unsuccessful in finding sequence homologs to CsV03-3 or any CsV03 family member; however, structural prediction models coupled with model comparison to Protein Data Bank folds indicated that the predicted polypeptide encoded by CsV03-3 has structural similarity to proteins with nucleic acid binding activity. Gel mobility shift assays performed on recombinant CsV03-3 protein demonstrated active binding with dsDNA and, to a lesser extent, ssDNA. Based on the phytohormone-inducible expression patterns, the ability to bind nucleic acids, and the lack of significant sequence homology to public databases, we propose that CsV03-3 and its related homologs defines a new class of nucleic acid binding proteins that are responsive to defense and stress signaling in woody perennials.
authors.affiliation: Horticulture & Breeding Research Unit, USDA ARS US Horticultural Research Laboratory, 2001 S. Rock Rd. Ft. Pierce, FL 34945, USA.
authors.forename: Jerry
authors.initials: J
authors.lastname: Mozoruk
authors.forename: Laura E
authors.initials: LE
authors.lastname: Hunnicutt
authors.forename: Wayne B
authors.initials: WB
authors.lastname: Hunter
authors.forename: Michael G
authors.initials: MG
authors.lastname: Bausher
mesh_terms: D001483:Base Sequence; D015139:Blotting, Southern; D002957:Citrus / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008969:Molecular Sequence Data; D054883:Oxylipins / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017433:Protein Structure, Secondary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020156:Salicylic Acid / Q000494:pharmacology; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics / Q000502:physiology
chemical_list: D003517:Cyclopentanes; D004268:DNA-Binding Proteins; D054883:Oxylipins; D010937:Plant Growth Regulators; D010940:Plant Proteins; C011006:jasmonic acid; D020156:Salicylic Acid