Taurine, by far the most abundant no cost amino p97 acid in mammals, with a lot of significant roles for example neuronal growth, had up to now only been reported for being synthetized in eukaryotes. Taurine will be the significant product of cysteine metabolic process in mammals, and its biosynthetic pathway consists of cysteine dioxygenase and cysteine sulfinic acid decarboxylase (hCSAD). Sequence, structural, and mutational selleck chemical KU-0063794 analyses of your structurally and sequentially connected hCSAD and human glutamic acid decarboxylase (hGAD) enzymes unveiled a 3 residue substrate recognition motif (X(one)aa(19)X(2)aaX(3)), inside the lively web page that is responsible for coordinating their respective preferred amino acid substrates.
Introduction with the cysteine sulfinic acid (CSA) motif into hGAD (hGAD-S192F/N212S/F214Y) resulted in an enzyme which has 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 selleck chemical Raf inhibitor 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.