Taurine, essentially the most abundant totally free amino p97 acid in mammals, with numerous important roles which include neuronal development, had to date only been reported to be synthetized in eukaryotes. Taurine would be the major solution of cysteine metabolic process in mammals, and its biosynthetic pathway consists of cysteine dioxygenase and cysteine sulfinic acid decarboxylase (hCSAD). Sequence, structural, and mutational mTORC1 analyses in the structurally and sequentially associated hCSAD and human glutamic acid decarboxylase (hGAD) enzymes uncovered a 3 residue substrate recognition motif (X(1)aa(19)X(two)aaX(three)), within the lively website that is certainly accountable for coordinating their respective favored amino acid substrates.
Introduction of your cysteine sulfinic acid (CSA) motif into hGAD (hGAD-S192F/N212S/F214Y) resulted in an enzyme with a >700 fold switch in selectivity toward the decarboxylation of CSA over its favored substrate, L-glutamic acid. Surprisingly, we found this CSA recognition motif in the genome sequences of several marine bacteria, prompting us to evaluate the catalytic properties of bacterial amino acid decarboxylases that were predicted by sequence motif to decarboxylate CSA but had been annotated as GAD enzymes. We show that CSAD from Synechococcus sp. PCC 7335 specifically decarboxylated CSA and that the bacteria accumulated intracellular taurine. The fact that CSAD homologues exist in Raf inhibitors certain bacteria and are frequently found in operons containing the recently discovered bacterial cysteine dioxygenases that oxidize L-cysteine to CSA supports the idea that a bona fide bacterial taurine biosynthetic pathway exists in prokaryotes.