alpha-keto acid chain elongation reactions involved in the biosynthesis of coenzyme B (7-mercaptoheptanoyl threonine phosphate) in methanogenic archaea

Experiments were performed to identify the biochemistry of the steps involved in the conversion of alpha-ketoglutarate and acetylCoA to alpha-ketosuberate in Methanosarcina thermophila. Trans-homoaconitrate was formed with the condensation of alpha-ketoglutarate and acetylCoA. Two consecutive elongation reactions involving alpha-ketoadipate that was formed from the dehydration and rehydration of cis-homoaconitate resulted to alpha-ketosuberate. A protein product from the Methanococcus gene served as a catalyst in one of the process.