The present invention describes an alternative approach to increase Taurine (Tau) or methionine (Met) production in eukaryotes, namely by the insertion of components of a sulfur-metabolic pathway and Tau- or Met-binding proteins in organisms where the peptides do not exist or have not clearly been identified. The invention describes methods for the use of polynucleotides that encode functional cysteine dioxygenase (CDO) alone, sulfinoalanine decarboxylase (SAD) alone or CDO and SAD polypeptides in combination with functional Tau- or Met-binding proteins in plants to increase Tau or Met production. The preferred embodiment of the invention is in plants but other organisms may be used. Increased Tau or Met availability will improve nutritional value of the crop.

The present invention describes an alternative approach to increase methionine (Met) production in eukaryotes, namely by the insertion of components of a sulfur-metabolic pathway in organisms where the pathway does not exist or has not clearly been identified. The invention describes methods for the use of polynucleotides that encode functional cysteine dioxygenase (CDO) alone or CDO and sulfinoalanine decarboxylase (SAD) polypeptides in plants to increase Met production. The preferred embodiment of the invention is in plants but other organisms may be used. Changes in Met availability will improve nutritional value of the crop.

A process for producing taurine. Where the taurine is produced from O-acetyl-L-serine (OAS) using biotransformation. In a first processing step (biotransformation 1), L-cysteic acid is produced from OAS using an enzyme selected from a class of OAS sulfhydrylases (EC 4.2.99.8) in the presence of a salt of sulfurous acid. Where the biotransformation is carried out under active pH control. In a second processing step (biotransformation 2), L-cysteic acid is decarboxylated to taurine. Where the OAS concentration in the batch is at least 10 g/L and the OAS sulfhydrylase is CysM.

Processes for producing L-cysteic acid along with uses for the same. The process includes providing a reaction of O-phospho-L-serine (OPS) with a salt of sulfurous acid (sulfite) and a cysteate synthase (CS enzyme) belonging to enzyme class EC 2.5.1.76 in a biotransformation. Where a concentration of OPS in a batch is at least 1 g/L and the CS enzyme is produced in an enzymatically active form by growth of the microorganism strain E. coli K12 JM105. The biotransformation is carried out under active pH control and the CS enzyme has an amino acid sequence specified in SEQ ID NO: 4 or an amino acid sequence homologous thereto. Where an amino acid sequence homologous to SEQ ID NO: 4 has a sequence identity of at least 50% in relation to SEQ ID NO: 4 and, at the same time, cysteate synthase enzyme activity.