Thursday, November 26, 2020

4 – 5.30 p.m.

On Zoom

Oxygen sensing in the green lineage

By Professor Francesco Licausi, Department of Plant Sciences, Wadham College

Abstract:

In all eukaryotes, molecular oxygen acts as a substrate for many biochemical reactions, among which respiration is essential for aerobic energy production. Different from animals, plants lack an active transport mechanism to distribute oxygen to all organism districts. Therefore, steep oxygen gradients are often observed inside many plant tissues, which can be exacerbated by environmental perturbations that further reduce oxygen availability. Plants evolved a number of strategies that allow them to cope with spatial and temporal variations in oxygen availability. Several of these involve metabolic adaptations to deal with energy crises induced by low oxygen. There responses are induced gradually when oxygen concentrations decrease and are rapidly reversed upon reoxygenation. A direct effect of the oxygen level can be observed in the stability, and thus activity, of group-VII Ethylene Response Factors (ERFs) that control the expression of hypoxia-induced genes. This proteolytic regulation, defined as the Arg/Cys-N-degron pathway, is triggered by enzymes that labels the N-termini of ERF-VII proteins with a sulfinic group, generated by oxidation of an N-terminal cysteine residue, thereby initiating a cascade of posttranslational modifications that ultimately results in ubiquitination and degradation. We recently outlined an overview of the responses to low oxygen stress in different plant taxa and identified the spread of ERF-VII and structural enzymes on the N-end rule pathway at different levels of plant complexity.

About the speaker

After studying green biotechnology in Parma and Pisa (2001-2006), Francesco Licausi spent four years in Germany: three for his doctoral studies shared between Scuola Superiore Sant’Anna (Pisa) and the University of Potsdam and one additional as a postdoc at Max Planck Institute of Molecular Plant Physiology. In this period, he contributed to the discovery of an oxygen sensing mechanism based on selective proteolysis adopted by plants to control their metabolic adaptation to hypoxia. In 2011, he returned to Italy, in Pisa, as an assistant professor at the Institute of Life Sciences of Scuola Sant’Anna, where he refined the hypoxia signalling pathway with the identification of the plant enzyme responsible for oxygen perception. Four years later, Dr. Licausi was hired by the Department of Biology at the University of Pisa as associate professor, where he re-directed his research towards the crosstalk between oxygen availability and developmental programmes in plant tissues. Since January 2020, Dr. Licausi has joined Wadham College as tutorial fellow and the Department of Plant Sciences as associate professor. Currently, his research interests deal with further exploration of the areas of evolution, developmental biology and synthetic biology, to study the similarities and differences between organisms belonging to different kingdoms of life in terms of oxygen requirements.