ADXR-ADX-P450, a putative electron transport system in plant mitocondria

AYELEN M. DISTÉFANO; ANDRES M. BELLIDO; DIEGO F. FIOL; EDUARDO J. ZABALETA; GABRIELA C. PAGNUSSAT

Rosario

Congreso; ICPMB 8th International Conference for Plant Mitochondrial Biology; 2013

ICPMB

In mammals and insects, adrenodoxin (ADX) mediates electron transfer from NADPH via adrenodoxin reductase (ADXR) to the terminal electron acceptor, mitochondrial cytochrome P450 (P450), which constitutes the first step in steroid hormones synthesis. Arabidopsis thaliana has an ADRX homologue and 2 for ADX, which are also located in the mitochondria. Although there are 244 P450s in Arabidopsis, the ones that have been analyzed, are not localized in the mitochondria. To study the possibility that a similar steroid biosynthetic pathway exists in plants we did first a bioinformatic analysis using 8 different softwares to predict cellular localization for P450s. We found 14 putative P450 with putative mitochondrial localization. To confirm their subcellular localization GFP translational fusions were made and their localization was studied by transient expression in Nicotiana Benthamiana. As a different approach, we performed a two-hybrid screening to detect interacting proteins using ADX1 as a bait. Also, T-DNA insertional double mutant plants for ADX1 and ADX2 and single mutants for ADXR were characterized, showing defects in female gametophyte. Since we could not obtain ADXR mutants in homozygosis, we designed amiRNAs targeting ADX1, ADX2 and ADXR proteins that were introduced into Arabidopsis, using an inducible vector. The phenotype of silenced plants will be shown.