title: Ascorbate oxidase is the potential conductor of a symphony of signaling pathways.
abstract: The functional role of ascorbate oxidase (AO; EC 1.10.3.3) has never been fully explained so far, due to the difficulties in understanding the presence of an enzyme specifically oxidizing ascorbate with no obvious advantage, and the apparent disadvantage of lowering plant stress resistance as a consequence of ascorbate consumption. Here we suggest a complete change of perspective, by proposing an essential role of AO as a modulator of both ascorbate and oxygen content, with relevant implications related to signaling. By affecting the overall redox state, AO is actually involved in redox regulation in the extracellular matrix. In addition, AO can contribute to creating a hypoxic microenvironment, especially relevant in the maintenance of meristem identity and the establishment of mutualistic plant-microbe interactions. We also hypothesize the possible involvement of AO in the activation of a signaling cascade analogous to the mechanism of prolyl hydroxylases/Hypoxia Inducible Factors in animals.
authors.affiliation: Department of Biology; University of Bari; Bari, Italy.
authors.forename: Mario C
authors.initials: MC
authors.lastname: De Tullio
authors.forename: Mike
authors.initials: M
authors.lastname: Guether
authors.forename: Raffaella
authors.initials: R
authors.lastname: Balestrini
mesh_terms: D000818:Animals; D001204:Ascorbate Oxidase / Q000378:metabolism*; D001205:Ascorbic Acid / Q000378:metabolism*; D005109:Extracellular Matrix; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases / Q000378:metabolism; D018519:Meristem / Q000201:enzymology* / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D010944:Plants / Q000201:enzymology* / Q000378:metabolism / Q000382:microbiology; D015398:Signal Transduction; D013559:Symbiosis
chemical_list: D010940:Plant Proteins; D001204:Ascorbate Oxidase; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D001205:Ascorbic Acid; D010100:Oxygen
keywords: ascorbate oxidase; hypoxic microenvironment; plant stem cells; plant-microbe interactions; redox regulation