DECIPHERING THE MOLECULAR ROLES OF IQD28 AND IQD30 PROTEINS OF ARABIDOPSIS THALIANA.

TRIASSI, AGUSTINA; DRINCOVICH, MARÍA FABIANA; LARA, MARÍA VALERIA

Buenos Aires

Congreso; Reunión Conjunta de Biociencias; 2017

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB)

Plant-specific IQ67 domain (IQD) members are part of an emergingfamily of calmodulin binding proteins. Although systematiccharacterization of this family has been carried out in various plantspecies, little is known about their biological roles. There are 33 IQDmembers distributed in four different classes in Arabidopsis thaliana.We have shown that IQD28 and -30 in vitro interact with calmodulinsin a calcium dependent and independent form. In addition, wehave observed that their transcriptional levels are increased in rootsin response to osmotic stress and drought. In this study, we haveadvanced in the characterization of two class IV proteins of Arabidopsis,IQD28 and -30. In order to identify specific ligands of theseproteins, we carried out pull down assays followed by mass spectrometry.For this purpose both recombinant proteins were immobilizedon affinity Ni2+-agarose columns, due to the presence of the histidinetag in its amino acid sequence. Subsequently, protein extracts fromadult roots of Arabidopsis plants were loaded to these columns. Afterseveral washes, bound proteins were eluted, precipitated withtrichloroacetic and analyzed by MALDI TOF TOF. Identified proteinsare predicted to be located at different cellular compartments, suchas, membrane, mitochondria, chloroplast, reticular and cytoskeletalcomponents. Interestingly, the most enriched cellular functionsamong the identified ligands are related to structural components,trafficking and cellular transport. These evidences might suggesta putative role of the IQDs as scaffold proteins. According to this,IQDs might be able to interact with multiple members of signalingpathways and recruit them to the components of the cytoskeleton.Thus, they could regulate the transduction of signals and assist thelocalization of cellular components in specific subcellular areas inresponse to various stimuli.