Phosphorylation of a member of the MBF1 transcriptional co-activator family, StMBF1, is stimulated in potato cell suspensions upon fungal elicitor challenge.
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.
Zanetti
María Eugenia
ME
Instituto de Investigaciones Biológicas-Departamento de Biología, Universidad Nacional de Mar del Plata, Funes 3250, CC 1245, 7600 Mar del Plata, Argentina.
Blanco
Flavio Antonio
FA
Daleo
Gustavo Raúl
GR
Casalongué
Claudia Anahí
CA
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
D010761:Phosphorus Radioisotopes; D010940:Plant Proteins; D015534:Trans-Activators; D004533:Egtazic Acid; D011494:Protein Kinases; D004121:Dimethyl Sulfoxide