"Pantothenate (vitamin B5) is a precursor to coenzyme A, which is an essential requirement for the metabolism of carbohydrates and fatty acids. The final step of bacterial and eukaryotic pantothenate biosynthesis is catalyzed by pantothenate synthetase (PTS), which is encoded by a single gene in Arabidopsis thaliana (AtPTS)." This pathway takes place in various organisms inside the Arabidopsis thaliana. Chloroplast, Mitochondrion, Peroxisome, Endoplasmic reticulum and Vacuole are all organisms involved in this process. This pathway is connected to other reactions such as the metabolism of Alanine, aspartate and glutamate, Cysteine and methionine and Arginine and proline. As examples of the reactions happening in this pathway, the following reactions can be mentioned: Pyruvic acid catalyzes into (S)-2-Acetolactate via Acetolactate synthase and its 2 subunits. This product catalyzes to (R)-2,3-Dihydroxy-isovalerate by Ketol-acid reductoisomerase and then it catalyzes into 3-Methyl-2-oxobutanoic acid by Dihydroxy-acid dehydratase. All of these reactions take place in the Chloroplast of Arabidopsis thaliana. 3-Methyl-2-oxobutanoic acid transports into the mitochondrion and catalyzes into either 2-Dehydropantoate (by 3-methyl-2-oxobutanoate hydroxymethyltransferase 1) or L-Valine ( by Branched-chain-amino-acid aminotransferase 2) inside the Mitochondrion.

Pantothenate and CoA Biosynthesis References