CHARACTERIZATION OF THE GOR GENE OF THE LACTIC-ACID BACTERIUM STREPTOCOCCUS-THERMOPHILUS CNRZ368

Cloning and characterization of the gor gene of the lactic acid bacter ium Streptococcus thermophilus, encoding glutathione reductase, are de scribed in this paper. This enzyme is a part of the enzymatic defences against oxidative stress in eukaryotic cells and in Gram-negative bac teria, but was never found in Gram-positive bacteria before this study . The amino acid sequence shares extensive similarities with glutathio ne reductases from other organisms, e.g. 62% amino acid identity with Escherichia coli protein. Northern blot analysis and glutathione reduc tase enzyme essays gave evidence that the gene is expressed in aerobic ally growing cells.