title: Signaling in the plant cytosol: cysteine or sulfide?
abstract: Cysteine (Cys) is the first organic compound containing reduced sulfur that is synthesized in the last stage of plant photosynthetic assimilation of sulfate. It is a very important metabolite not only because it is crucial for the structure, function and regulation of proteins but also because it is the precursor molecule of an enormous number of sulfur-containing metabolites essential for plant health and development. The biosynthesis of Cys is accomplished by the sequential reaction of serine acetyltransferase (SAT) and O-acetylserine(thiol)synthase (OASTL). In Arabidopsis thaliana, the analysis of specific mutants of members of the SAT and OASTL families has demonstrated that the cytosol is the compartment where the bulk of Cys synthesis takes place and that the cytosolic OASTL enzyme OAS-A1 is the responsible enzyme. Another member of the OASTL family is DES1, a novel L-cysteine desulfhydrase that catalyzes the desulfuration of Cys to produce sulfide, thus acting in a manner opposite to that of OAS-A1. Detailed studies of the oas-a1 and des1 null mutants have revealed the involvement of the DES1 and OAS-A1 proteins in coordinate regulation of Cys homeostasis and the generation of sulfide in the cytosol for signaling purposes. Thus, the levels of Cys in the cytosol strongly affect plant responses to both abiotic and biotic stress conditions, while sulfide specifically generated from the degradation of Cys negatively regulates autophagy induced in different situations. In conclusion, modulation of the levels of Cys and sulfide is likely critical for plant performance.
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicias, Universidad de Sevilla, Avenida Américo Vespucio, 49, 41092, Seville, Spain. gotor@ibvf.csic.es.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Gotor
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicias, Universidad de Sevilla, Avenida Américo Vespucio, 49, 41092, Seville, Spain.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Laureano-Marín
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicias, Universidad de Sevilla, Avenida Américo Vespucio, 49, 41092, Seville, Spain.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Moreno
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicias, Universidad de Sevilla, Avenida Américo Vespucio, 49, 41092, Seville, Spain.
authors.forename: Ángeles
authors.initials: Á
authors.lastname: Aroca
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicias, Universidad de Sevilla, Avenida Américo Vespucio, 49, 41092, Seville, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: García
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicias, Universidad de Sevilla, Avenida Américo Vespucio, 49, 41092, Seville, Spain.
authors.forename: Luis C
authors.initials: LC
authors.lastname: Romero
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D006706:Homeostasis; D015398:Signal Transduction; D013440:Sulfides / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D013440:Sulfides; D003545:Cysteine
keywords: Abiotic stress; Arabidopsis; Autophagy; Biotic stress; Sulfur metabolism