Low abundance does not mean less importance in cysteine metabolism.
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.
Gotor
Cecilia
C
Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Sevilla, Spain.
Alvarez
Consolación
C
Bermúdez
M Angeles
MA
Moreno
Inmaculada
I
García
Irene
I
Romero
Luis C
LC
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*
D007527:Isoenzymes; D010940:Plant Proteins; C011119:S-sulphocysteine; C018725:O-acetylhomoserine (thiol)-lyase; D019757:Carbon-Oxygen Lyases; D003545:Cysteine