Biomedical subjects

Britta Walter

Publications and source records attributed to Britta Walter.

3 recordsLinked to original sources

PubMed2007

Nitrogen metabolism and nitrogen control in corynebacteria: variations of a common theme.

The published genome sequences of Corynebacterium diphtheriae, Corynebacterium efficiens, Corynebacterium glutamicum and Corynebacterium jeikeium were screened for genes encoding central components of nitrogen source uptake, nitrogen assimilation and nitrogen control systems. Interestingly, the soil-living species C. efficiens and C. glutamicum exhibit a broader spectrum of genes for nitrogen transport and metabolism than the pathogenic species C. diphtheriae and C. jeikeium. The latter are characterized by gene decay and loss of functions like urea metabolism and nitrogen-dependent transcription control. The global regulator of nitrogen regulation AmtR and its DNA-binding motif are conserved in C. diphtheriae, C. efficiens and C. glutamicum, while in C. jeikeium, an AmtR-encoding gene as well as putative AmtR-binding motifs are missing.

Amino Acid Motifs↗

PubMed2006

Ammonium toxicity in bacteria.

Although an excellent nitrogen source for most bacteria, ammonium was-in analogy to plant and animal systems-assumed be detrimental to bacteria when present in high concentrations. In this study, we examined the effect of molar ammonium concentrations on different model bacteria, namely, Corynebacterium glutamicum, Escherichia coli, and Bacillus subtilis. The studied bacteria are highly resistant to ammonium. When growth was impaired upon addition of molar (NH4)2SO4 concentrations, this was not caused by an ammonium-specific effect but was due to an enhanced osmolarity or increased ionic strength of the medium. Therefore, it was concluded that ammonium is not detrimental to C. glutamicum and other bacteria even when present in molar concentrations.

Bacillus subtilis↗

PubMed2005

DNA microarray analysis of the nitrogen starvation response of Corynebacterium glutamicum.

Nitrogen is an essential component of nearly all of the complex macromolecules in a bacterial cell, e.g. proteins, nucleic acids, and cell wall components. Accordingly, most prokaryotes have developed elaborate control mechanisms to provide an optimal supply of nitrogen for cellular metabolism and to cope with situations of nitrogen limitation. In this communication, a global analysis of the Corynebacterium glutamicum nitrogen starvation response by transcriptional profiling using DNA microarrays is presented. Our results show that C. glutamicum reacts to nitrogen starvation with a rearrangement of the cellular transport capacity, changes in metabolic pathways concerning nitrogen assimilation and amino acid biosynthesis, and a decreased capacity for protein synthesis.

Adaptation, Physiological↗