title: The water- and salt-stress-regulated Asr1 (abscisic acid stress ripening) gene encodes a zinc-dependent DNA-binding protein.
abstract: Tomato (Lycopersicon esculantum) ASR1 (abscisic acid stress ripening protein), a small plant-specific protein whose cellular mode of action defies deduction based on its sequence or homology analyses, is one of numerous plant gene products with unknown biological roles that become over-expressed under water- and salt-stress conditions. Steady-state cellular levels of tomato ASR1 mRNA and protein are transiently increased following exposure of plants to poly(ethylene glycol), NaCl or abscisic acid. Western blot and indirect immunofluorescence analysis with anti-ASR1 antibodies demonstrated that ASR1 is present both in the cytoplasmic and nuclear subcellular compartments; approx. one-third of the total ASR1 protein could be detected in the nucleus. Nuclear ASR1 is a chromatin-bound protein, and can be extracted with 1 M NaCl, but not with 0.5% Triton X-100. ASR1, overexpressed in Escherichia coli and purified to homogeneity, possesses zinc-dependent DNA-binding activity. Competitive-binding experiments and SELEX (systematic evolution of ligands by exponential enrichment) analysis suggest that ASR1 binds at a preferred DNA sequence.
authors.affiliation: Department of Life Sciences and The Doris and Bertie Black Center for Bioenergetics in Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
authors.forename: Yossi
authors.initials: Y
authors.lastname: Kalifa
authors.forename: Ayelet
authors.initials: A
authors.lastname: Gilad
authors.forename: Zvia
authors.initials: Z
authors.lastname: Konrad
authors.forename: Michele
authors.initials: M
authors.lastname: Zaccai
authors.forename: Pablo A
authors.initials: PA
authors.lastname: Scolnik
authors.forename: Dudy
authors.initials: D
authors.lastname: Bar-Zvi
mesh_terms: D001665:Binding Sites / Q000235:genetics; D002458:Cell Fractionation / Q000379:methods; D018744:DNA, Plant / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D018551:Solanum lycopersicum / Q000166:cytology / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D012965:Sodium Chloride / Q000378:metabolism*; D013347:Subcellular Fractions / Q000737:chemistry; D014867:Water / Q000378:metabolism*; D016335:Zinc Fingers / Q000235:genetics*
chemical_list: C091853:Asr1 protein, Lycopersicon esculentum; D018744:DNA, Plant; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D014867:Water; D012965:Sodium Chloride