Differential proteome of arabidopsis roots form an IQD30 mutant line?

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

Salta

Congreso; LV Reunión Anual de SAIB - XIV PABMB. 2019.; 2019

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Plant-specific IQ67 domain (IQD) members are part of an emerging family of calmodulin binding proteins. Although systematic characterization of this family has been carried out in various plants species, little is known about their biological roles. In this study, we made progresses in the characterization of IQD30 from Arabidopsis thaliana. It was previously reported that IQD30 is capable of binding to microtubules. At the same time, in vitro assays corroborated the interaction between IQD30 and calmodulins in a calcium dependent and independent ways. In order to evaluate the role of IQD30, a loss of function mutant (Salk_052513) and a proteomic approach were used. For this purpose, proteins were extracted from 8-day-old seedling roots and subjected to quantitative proteomics through LC/MS using CEQUIBIEM facilities (Argentina). Three biological replicates for each genotype were used. Statistical data analysis was performed using Perseus software. In total, 152 differential proteins were identified (p≤0.05; 0.5>fold change>2). Remarkably, 70% of differentially expressed proteins are induced in the mutant genotype. Functional categorization indicates differential proteins are involved in different metabolic processes; such as, protein synthesis machinery, proteasome components, hormone signaling, cytoskeleton components, calcium signaling among others. Induced expression of three auxin signaling proteins, ARF-GAP2, ZIGA4 and BIG, which usually increase their levels in response to auxins, was observed in the mutant line. This result is in agreement with lower primary root elongation of iqd30 than Col-0 line under both normal growth conditions and IAA treatment, and with transcriptionally response of iqd30 to auxin treatment. Collectively, these results suggest IQD30 could have a role in auxin signaling. On the other hand, proteomic analysis revealed the differential expression of two calcium signaling proteins in iqd30. While CML42 (a calmodulin like protein) was only identified in iqd30 line, CDPK6 (a calcium dependent kinase) was decreased in idq30 with respect to Col-0. In addition, the 4-fold increase of MAP65.2 (a microtubule associated protein that connects microtubule organization to the polarization of auxin exporters) and the 2-fold decrease of β tubulin 6 (a structural microtubule protein) was also observed in the mutant line. According to this, previous pull down assays followed by MS revealed β tubulin 6 as a putative ligand of IQD30. Based on these results and according to previous evidences, auxin and calcium signaling could be integrated to modulate microtubules dynamics, by means of IQD30 protein. IQD30 might be able to interact with multiple members of signaling pathways and recruit them to cytoskeleton regulating the transduction of signals in response to various stimuli.