Characterization of Arabidopsis thaliana E3-ubiquitin-ligase SINA-L7

PERALTA, DA; DIEGO FABIAN GOMEZ CASATI; BUSI, M. V.

Mendoza

Congreso; XLVIII SAIB; 2012

SAIB

  Arabidopsis Seven in absentia like 7 (SINA-L7) is a putative Zinc finger (SIAH-like) protein belonging to the seven in absentia family composed by at least 35 proteins. It is expressed in various growth stages and almost all plant tissues. Its homolog was first identified in Drosophila associated with the development of photoreceptors, cell cycle arrest and protein polyubiquitination. Recently, about 50 SIAH-1 (human homolog) substrate proteins in a context of degradation mediated mostly by proteosome have been described in the literature. Due to the importance of the study of protein degradation by means of polyubiquitination pathway, we face SINA-L7 characterization by studying the expression of its transcript by qPCR in various plant tissues of Arabidopsis. Results show that SINA-L/7 is highly expressed in tissues with active cell division. In addition, we found that the expression of SINA-L7 follows a circadian rhythm and that UV exposure doubles its expression. Using an ubiquitination assay we found that SINA-L7 has E3 ubiquitin ligase activity and that residue K124 is involved in such process. Therefore our findings show that SINA-L7 is E3 ubiquitin ligase that would be involved in protein labeling by polyubiquitination.