The CymR regulator in complex with the enzyme CysK controls cysteine metabolism in Bacillus subtilis.

Several enzymes have evolved as sensors in signal transduction pathways to control gene expression, thereby allowing bacteria to adapt efficiently to environmental changes. We recently identified the master regulator of cysteine metabolism in Bacillus subtilis, CymR, which belongs to the poorly characterized Rrf2 family of regulators. We now report that the signal transduction mechanism controlling CymR activity in response to cysteine availability involves the formation of a stable complex with CysK, a key enzyme for cysteine biosynthesis.

Sequence analysis of the mobilizable lactococcal plasmid pGdh442 encoding glutamate dehydrogenase activity.

A novel plasmid named pGdh442 had previously been isolated from a plant Lactococcus lactis strain. This plasmid encodes two interesting properties with applications in the dairy industry: a glutamate dehydrogenase activity that stimulates amino acid conversion to aroma compounds, and cadmium/zinc resistance that can be used as a selectable marker. Moreover, this plasmid can be transferred naturally to other strains, but appears to be incompatible with certain other lactococcal plasmids.

Glutamate dehydrogenase activity can be transmitted naturally to Lactococcus lactis strains to stimulate amino acid conversion to aroma compounds.

Amino acid conversion to aroma compounds by Lactococcus lactis is limited by the low production of alpha-ketoglutarate that is necessary for the first step of conversion. Recently, glutamate dehydrogenase (GDH) activity that catalyzes the reversible glutamate deamination to alpha-ketoglutarate was detected in L. lactis strains isolated from a vegetal source, and the gene responsible for the activity in L.

The gene encoding the glutamate dehydrogenase in Lactococcus lactis is part of a remnant Tn3 transposon carried by a large plasmid.

The gene responsible for the uncommon glutamate dehydrogenase (GDH) activity of Lactococcus lactis was identified and characterized. It encodes a GDH of family I that is mainly active in glutamate biosynthesis, is carried by a large plasmid, and is included, with functional cadmium resistance genes, in a remnant Tn3-like transposon.

Glutamate dehydrogenase activity: a major criterion for the selection of flavour-producing lactic acid bacteria strains.

Lactic acid bacteria (LAB) have the enzyme potential to transform amino acids into aroma compounds that contribute greatly to cheese flavour. Generally, amino acid conversion by LAB is limited by their low production of alpha-ketoglutarate since this alpha-ketoacid is essential for the first step of the conversion. Indeed, we have demonstrated that adding exogenous alpha-ketoglutarate to cheese curd, as well as using a genetically modified L.