A mitochondrial ferredoxin shuttle and its role in steroid biosynthesis, patterning and fertilization of the Arabidopsis embryo sac

DISTEFANO, AYELEN; BELLIDO, ANDRES; MARTIN, MARIA VICTORIA; FIOL, DIEGO F.; ZABALETA, EDUARDO J.; PAGNUSSAT, GABRIELA C.

Tucson

Conferencia; Plant Reproduction 2016; 2016

International Association of Sexual Plant Reproduction Research (IASPRR)

Mitochondrial ferredoxins, also known as adrenodoxins (ADXs), are small iron-sulfur proteins encoded by nuclear genes that are ubiquitously found in plants, animals, and bacteria. They belong to the large family of [2Fe-2S]-type ferredoxins and have electron transfer properties. In animals, ADXs function as mobile shuttles that transfer electrons between an adrenodoxin reductase (ADXR) and mitochondrial P450s. The activity of ADXR is essential for the synthesis of steroid hormones in animals, as participates in the reduction of a mitochondrial cytochrome P450 that leads to steroidogenesis. The study of adxr mutants and double mutants for ADX1 and ADX2 revealed that the activity of this shuttle is important for female gametophyte patterning and function. Mutant embryo sacs are able to reach a mature stage but arrest soon after fertilization, probably due to abnormalities observed in the specification of the egg cell. To unveil the molecular functions of this electron shuttle in Arabidopsis, we looked for ADX-ADXR redox partners through yeast two-hybrid screenings and bimolecular fluorescence complementation assays. Several putative mitochondrial ADX redox partners, including three cytochrome P450s. Supported by ANPCyT, CONICET and HHMI