The h-region of twin-arginine signal peptides supports productive binding of bacterial Tat precursor proteins to the TatBC receptor complex.

The twin-arginine translocation (Tat) pathway transports folded proteins across bacterial membranes. Tat precursor proteins possess a conserved twin-arginine (RR) motif in their signal peptides that is involved in their binding to the Tat translocase, but some facets of this interaction remain unclear. Here, we investigated the role of the hydrophobic (h-) region of the trimethylamine -oxide reductase (TorA) signal peptide in TatBC receptor binding and We show that besides the RR motif, a minimal, functional h-region in the signal peptide is required for Tat-dependent export in Furthermore, we identified mutations in the h-region that synergistically suppressed the export defect of a TorA[KQ]-30aa-MalE Tat reporter protein in which the RR motif was replaced with a lysine-glutamine pair.

Visualization of imbalances in sulfur assimilation and synthesis of sulfur-containing amino acids at the single-cell level.

We describe genetically encoded sensors which transmit elevated cytosolic concentrations of O-acetyl serine (OAS) and O-acetyl homoserine (OAH)-intermediates of l-cysteine and l-methionine synthesis-into an optical output. The sensor pSenOAS3 elicits 7.5-fold-increased fluorescence in cultures of a Corynebacterium glutamicum strain that excrete l-cysteine.

Transmembrane insertion of twin-arginine signal peptides is driven by TatC and regulated by TatB.

The twin-arginine translocation (Tat) pathway of bacteria and plant chloroplasts mediates the transmembrane transport of folded proteins, which harbour signal sequences with a conserved twin-arginine motif. Many Tat translocases comprise the three membrane proteins TatA, TatB and TatC. TatC was previously shown to be involved in recognizing twin-arginine signal peptides.

Genetic evidence for a tight cooperation of TatB and TatC during productive recognition of twin-arginine (Tat) signal peptides in Escherichia coli.

The twin arginine translocation (Tat) pathway transports folded proteins across the cytoplasmic membrane of bacteria. Tat signal peptides contain a consensus motif (S/T-R-R-X-F-L-K) that is thought to play a crucial role in substrate recognition by the Tat translocase. Replacement of the phenylalanine at the +2 consensus position in the signal peptide of a Tat-specific reporter protein (TorA-MalE) by aspartate blocked export of the corresponding TorA(D(+2))-MalE precursor, indicating that this mutation prevents a productive binding of the TorA(D(+2)) signal peptide to the Tat translocase.

A tetracycline inducible expression vector for Corynebacterium glutamicum allowing tightly regulable gene expression.

Here we report on the construction of a tetracycline inducible expression vector that allows a tightly regulable gene expression in Corynebacterium glutamicum which is used in industry for production of small molecules such as amino acids. Using the green fluorescent protein (GFP) as a reporter protein we show that this vector, named pCLTON1, is characterized by tight repression under non-induced conditions as compared to a conventional IPTG inducible expression vector, and that it allows gradual GFP synthesis upon gradual increase of anhydrotetracycline addition.

A periplasmic, pyridoxal-5'-phosphate-dependent amino acid racemase in Pseudomonas taetrolens.

The pyridoxal-5'-phosphate (PLP)-dependent amino acid racemases occur in almost every bacterium but may differ considerably with respect to substrate specificity. We here isolated the cloned broad substrate specificity racemase ArgR of Pseudomonas taetrolens from Escherichia coli by classical procedures. The racemase was biochemically characterized and amongst other aspects it was confirmed that it is mostly active with lysine, arginine and ornithine, but merely weakly active with alanine, whereas the alanine racemase of the same organism studied in comparison acts on alanine only.

Escherichia coli twin arginine (Tat) mutant translocases possessing relaxed signal peptide recognition specificities.

The twin arginine (Tat) secretion pathway allows the translocation of folded proteins across the cytoplasmic membrane of bacteria. Tat-specific signal peptides contain a characteristic amino acid motif ((S/T)RRXFLK) including two highly conserved consecutive arginine residues that are thought to be involved in the recognition of the signal peptides by the Tat translocase. Here, we have analyzed the specificity of Tat signal peptide recognition by using a genetic approach.