title: Phosphorylation of a member of the MBF1 transcriptional co-activator family, StMBF1, is stimulated in potato cell suspensions upon fungal elicitor challenge.
abstract: StMBF1 (Solanum tuberosum multiprotein bridging factor 1) is a plant member of the MBF1 family of transcriptional co-activators. Previously, it has been described as being up-regulated at the transcriptional level by fungal and abiotic stress. To understand whether StMBF1 is also regulated at the post-translational level, in vitro as well as in vivo phosphorylation assays were performed. StMBF1 is phosphorylated under both experimental conditions and [(32)P] incorporation into StMBF1 increases after treatment of potato cells with hyphal cell wall components (HWC) derived from Phytophthora infestans. The StMBF1-phosphorylating activity is strongly inhibited by the calcium-chelator EGTA and partially inhibited by calmodulin antagonists. Using bacterial purified StMBF1 as a substrate, a 57 kDa calcium-dependent protein kinase (p57) that is able to phosphorylate StMBF1 was detected. The StMBF1 kinase activity of p57 was higher in elicited than in non-treated cells. The role of the elicitor-dependent phosphorylation of StMBF1 is discussed.
authors.affiliation: Instituto de Investigaciones Biológicas-Departamento de Biología, Universidad Nacional de Mar del Plata, Funes 3250, CC 1245, 7600 Mar del Plata, Argentina.
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: Zanetti
authors.forename: Flavio Antonio
authors.initials: FA
authors.lastname: Blanco
authors.forename: Gustavo Raúl
authors.initials: GR
authors.lastname: Daleo
authors.forename: Claudia Anahí
authors.initials: CA
authors.lastname: Casalongué
mesh_terms: D002478:Cells, Cultured; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D007113:Immunity, Innate / Q000235:genetics; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation / Q000187:drug effects; D010838:Phytophthora / Q000254:growth & development*; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D011198:Solanum tuberosum / Q000166:cytology / Q000235:genetics* / Q000382:microbiology; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism
chemical_list: D010761:Phosphorus Radioisotopes; D010940:Plant Proteins; D015534:Trans-Activators; D004533:Egtazic Acid; D011494:Protein Kinases; D004121:Dimethyl Sulfoxide