Arabidopsis thaliana (Ath) peroxisomal (Per) CS_like. CS catalyzes the condensation of acetyl coenzyme A (AcCoA) and oxalacetate (OAA) to form citrate and coenzyme A (CoA), the first step in the citric acid cycle (TCA or Krebs cycle). The overall CS reaction is thought to proceed through three partial reactions and involves both closed and open conformational forms of the enzyme: a) the carbanion or equivalent is generated from AcCoA by base abstraction of a proton, b) the nucleophilic attack of this carbanion on OAA to generate citryl-CoA, and c) the hydrolysis of citryl-CoA to produce citrate and CoA. This group contains three Arabidopsis peroxisomal CS proteins, CYS1, -2, and -3 which are involved in the glyoxylate cycle. AthCYS1, in addition to a peroxisomal targeting sequence, has a predicted secretory signal peptide; it may be targeted to both the secretory pathway and the peroxisomes and is thought to be located in the extracellular matrix. AthCSY1 is expressed only in siliques and specifically in developing seeds. AthCSY2 and 3 are active during seed germination and seedling development and are thought to participate in the beta-oxidation of fatty acids.
Jiyao W et al.(2023). "The conserved domain database in 2023.",