Towards understanding the interplay between ProDH and ROS burst in plant hypersensitive response

RIZZI YS; FABRO G; ALVAREZ ME

Cordoba

Congreso; LII Reunión Anual SAIB; 2016

Proline dehydrogenase (ProDH) is the limiting enzyme in the transformation of proline (Pro) into glutamic acid (Glu) occurring at mitochondria. This enzyme is required for normal development of the hypersensitive response (HR) against the biotrophic pathogen Pseudomonas syringae pv tomato Avr-Rpm1, and the generation of ROS by the plasma membrane NADPH oxidase, RBOHD. The different subcellular localization of ProDH and RBOHD excludes a direct interaction of these enzymes. We here analyze different possibilities that could explain their coordination. ProDH generates Δ1-pirroline-5-carboxilate (P5C) and FADH2 loading electrons into the mitochondrial electron transport chain (mETC), and its over activation may affect mitochondrial ROS (mROS) and ATP levels. Moreover, Pro catabolism could induce Pro synthesis that takes place at the cytosol consuming NADPH, thus exchanging redox cofactors between both compartments. In this context ProDH could operate either with the second catabolic enzyme P5C dehydrogenase (P5CDH) cycling Pro and Glu, or with the second biosynthetic enzyme P5C reductase (P5CR) cycling Pro and P5C. To start unraveling the mechanisms connecting these mitochondrial and plasma membranes events we analyzed redox alterations derived from ProDH activation in the absence of P5CDH or P5CR.