title: Mapping the diatom redox-sensitive proteome provides insight into response to nitrogen stress in the marine environment.
abstract: Diatoms are ubiquitous marine photosynthetic eukaryotes responsible for approximately 20% of global photosynthesis. Little is known about the redox-based mechanisms that mediate diatom sensing and acclimation to environmental stress. Here we used a quantitative mass spectrometry-based approach to elucidate the redox-sensitive signaling network (redoxome) mediating the response of diatoms to oxidative stress. We quantified the degree of oxidation of 3,845 cysteines in the Phaeodactylum tricornutum proteome and identified approximately 300 redox-sensitive proteins. Intriguingly, we found redox-sensitive thiols in numerous enzymes composing the nitrogen assimilation pathway and the recently discovered diatom urea cycle. In agreement with this finding, the flux from nitrate into glutamine and glutamate, measured by the incorporation of (15)N, was strongly inhibited under oxidative stress conditions. Furthermore, by targeting the redox-sensitive GFP sensor to various subcellular localizations, we mapped organelle-specific oxidation patterns in response to variations in nitrogen quota and quality. We propose that redox regulation of nitrogen metabolism allows rapid metabolic plasticity to ensure cellular homeostasis, and thus is essential for the ecological success of diatoms in the marine ecosystem.
authors.affiliation: Department of Plant Sciences and Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Shilo
authors.initials: S
authors.lastname: Rosenwasser
authors.forename: Shiri
authors.initials: S
authors.lastname: Graff van Creveld
authors.forename: Daniella
authors.initials: D
authors.lastname: Schatz
authors.forename: Sergey
authors.initials: S
authors.lastname: Malitsky
authors.forename: Oren
authors.initials: O
authors.lastname: Tzfadia
authors.forename: Asaph
authors.initials: A
authors.lastname: Aharoni
authors.forename: Yishai
authors.initials: Y
authors.lastname: Levin
authors.forename: Alexandra
authors.initials: A
authors.lastname: Gabashvili
authors.forename: Ester
authors.initials: E
authors.lastname: Feldmesser
authors.forename: Assaf
authors.initials: A
authors.lastname: Vardi
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D002853:Chromatography, Liquid; D017377:Diatoms / Q000378:metabolism* / Q000502:physiology; D006706:Homeostasis / Q000502:physiology*; D013058:Mass Spectrometry; D009584:Nitrogen / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology*; D020543:Proteome / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D020543:Proteome; D009584:Nitrogen
keywords: marine diatoms; phytoplankton; redox proteomics; roGFP