Characterization of Arabidopsis E3-ubiquitin-ligase SINA-L7, a potential mediator of a RRM and its interaction with GAPC.

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

Buenos Aires

Congreso; . Ubiquitin & ubiquitin-like proteins: At the crossroads from chromatin to protein Meeting; 2014

Ub Congress Committee

Arabidopsis Seven in absentia like 7 (SINA-L7), belonging to the seven in absentia family is a putative Zinc finger (SIAH-like) nuclear-cytosolic protein that 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. Previously, we found SINA-L7 expression altered in three different lines of plants displaying mitochondrial dysfunction what turns SINA-L7 a potential mediator of a RRM. Particularly, SINA-L7 is induced in gapc-1 knock out plants. It has been postulated that the glycolytic enzyme GAPC, also found in the nucleus and associated to the mitochondrial external membrane in plants, may have other important roles. However, little is known about these possible secondary functions in higher plants. It was recently reported that human and murine GAPC binds an E3-ligase and is translocated to the nucleus. In this context, we face the characterization of SINA-L7 and study its interaction with GAPC in vitro. Results show that SINA-L7 is highly expressed in tissues with active cell division and it is induced also after UV exposure. Furthermore, using an ubiquitination assay we found that SINA-L7 has E3-ubiquitin ligase activity and that the K124 residue is involved in such process. In addition, SINA-L7 ubiquitinates and physically interacts with GAPC by pull down analysis and residue K231 in GAPC is responsible of its interaction. Furthermore, residue K76 in GAPC is ubiquitinated by SINA-L7, and this modification is probably to regulate GAPC´s activity