Identification and deep analysis of the molecular requirements for monocot malic enzymes

GISMONDI MAURO; SAIGO, MARIANA; ANDREO, CARLOS SANTIAGO; DRINCOVICH, MARÍA FABIANA

Congreso; Reunión conjunta de sociedades de biociencias; 2017

NADP-dependent malic enzyme (NADP-ME) is widespread in nature and involved in different metabolic pathways due to the relevant physiological functions of its substrates (malate) and products (pyruvate and NADPH). In plants, this gene family harbours several members although the biological roles of each of them remain still unknown. Phylogenetic analysis of NADP-ME proteins from monocot species revealed the existence of four taxonomic lineages, consisting of orthologue peptides with conserved amino acidic and structural features. Here, we explored the conservation of molecular requirements responsible for the specific spatio-temporal expression patterns of each NADP-ME lineage, in order to deepen the understanding of their biological functions. In particular, previous transcriptional studies allowed us to classify a maize NADP-ME isoform as embryo-specific. An own design software was applied to perform a deep analysis on the regulatory sequences of more than ten orthologous genes of this clade and a novel cis-regulatory module (CRM) was identified. This conserved arrangement of motifs included two specific ABREs (ABA-Responsive Element) and other uncharacterized cis-elements. Moreover, the study of their proximal genomic context revealed the putative bidirectionality of these promoters, sharing the found cis-elements and their potential functionality with OVA4 (OVule Abortion 4), a gene with a reported role in embryo development. In silico transcriptional evidences were explored for these adjacent genes and also for potential trans regulators of their promoters in monocot seed development. These findings, along with distinct conserved features found for the other lineages, provide new insights and trigger new hypothesis in order to unravel the specific roles of each NADP-ME isoform, to validate their possible redundancy, and to understand the extents of the functional diversity of this family of metabolic enzymes