BSL protein phosphatases in Arabidopsis thaliana

MARIO RICO; JAVIER BIANCHI; ARIEL CHERNOMORETZ; SANTIAGO MORA-GARCIA

Tucuman, Argentina

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> BSL phosphatases are members of a poorly characterised branch of the PPP family of Ser/Thr phosphatases. Found only in green algae, plants and alveolates, they stand apart among other PPP phosphatases by their structure: an N-terminal b-propeller domain linked by a connecting sequence to the C-terminal catalytic domain. To date, the only function ascribed to these proteins is the modulation of the brassinosteroid signal strength in plants. We set out to study their functions as a way to understand the evolution of signal transduction pathways in multicellular organisms. There are four members of the BSL family in Arabidopsis thaliana. We report the phenotypic and physiological characterisation of plants mutant for BSL2 and BSL3. Both genes share high sequence similarity and their expression patterns extensively overlap. The BSL2 protein appears both in the cytoplasm and in the nucleus, and this pattern is observed even when each domain is expressed separately. Single mutants are normal, but when the function of both genes is disrupted, plants display a series of severe phenotypic defects ranging from reduced stature to complete sterility. Whereas the responses to the application of brassinosteroid are mostly unaltered, we detected an altered response to auxin. Finally, we analysed changes in global gene expression and found 829 significantly misregulated genes in the double mutants.