title: Low abundance does not mean less importance in cysteine metabolism.
abstract: The cysteine molecule plays an essential role in cells because it is part of proteins and because it functions as a reduced sulfur donor molecule. In addition, the cysteine molecule may also play a role in the redox signaling of different stress processes. Even though the synthesis of cysteine by the most abundant of the isoforms of O-acetylserine(thiol)lyase in the chloroplast, the mitochondria and the cytosol is relatively well-understood, the role of the other less common isoforms homologous to O-acetylserine(thiol)lyase is unknown. Several studies on two of these isoforms, one located in the cytosol and the other one in the chloroplast, have shown that while one isoform operates with a desulfhydrase activity and is essential to regulate the homeostasis of cysteine in the cytosol, the other, located in the chloroplast, synthesizes S-sulfocysteine. This metabolite appears to be essential for the redox regulation of the chloroplast under certain lighting conditions.
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Sevilla, Spain.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Gotor
authors.forename: Consolación
authors.initials: C
authors.lastname: Alvarez
authors.forename: M Angeles
authors.initials: MA
authors.lastname: Bermúdez
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Moreno
authors.forename: Irene
authors.initials: I
authors.lastname: García
authors.forename: Luis C
authors.initials: LC
authors.lastname: Romero
mesh_terms: D019757:Carbon-Oxygen Lyases / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D003545:Cysteine / Q000031:analogs & derivatives* / Q000096:biosynthesis; D003600:Cytosol / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D010940:Plant Proteins; C011119:S-sulphocysteine; C018725:O-acetylhomoserine (thiol)-lyase; D019757:Carbon-Oxygen Lyases; D003545:Cysteine