Summary The bacterial cell wall is made of peptidoglycan (PG), a polymer that is essential for maintenance of cell shape and survival. Many bacteria alter their PG chemistry as a strategy to adapt their cell wall to external challenges. Therefore, identifying these environmental cues is important to better understand the interplay between microbes and their habitat. Here, we used the soil bacterium Pseudomonas putida to uncove...

Summary In many Thermus thermophilus strains, nitrate respiration is encoded in mobile genetic regions, along with regulatory circuits that modulate its expression based on anoxia and nitrate presence. The oxygen‐responsive system has been identified as the product of the dnrST ( dnr ) operon located immediately upstream of the nar operon ( narCGHJIKT ), which encodes the nitrate reductase (NR) and nitrate/nitrite transporters...

Summary Enzymes catalysing the stereo‐chemical inter‐conversion of amino acids are known as amino acid racemases. In bacteria, these enzymes are fundamental to synthesize the D ‐ A la and D ‐ G lu that are critical components of the peptidoglycan. In addition to this structural function in cell wall assembly, D ‐amino acids produced by microbial amino acid racemases have been described as relevant constituents in other prokary...

Summary Changes in the peptidoglycan ( PG ) structure of S almonella enterica are detected in the presence of a sublethal concentration of sodium deoxycholate ( DOC ): (i) lower proportions of B raun lipoprotein ( Lpp )‐bound muropeptides; (ii) reduced levels of muropeptides cross‐linked by L (meso)‐diaminopimelyl‐ D (meso)‐diaminopimelic acid ( L ‐ D ) peptide bridges (3‐3 cross‐links). Similar structural changes are found in...

Summary The biological roles of low molecular weight penicillin‐binding proteins ( LMW PBP ) have been difficult to discern in G ram‐negative organisms. In E scherichia coli , mutants lacking these proteins often have no phenotype, and cells lacking all seven LMW PBPs remain viable. In contrast, we report here that V ibrio cholerae lacking DacA ‐1, a PBP 5 homologue, displays slow growth, aberrant morphology and altered peptid...

Summary Superfolder GFP (sGFP) is a variant of the Green Fluorescent Protein that folds efficiently when fused to poorly folded proteins. In this study, we show that sGFP, but not enhanced GFP, is functional in vivo at 70°C in the extreme thermophile Thermus thermophilus ( Tth ); thus, permitting the use of sGFP as a localization tag in vivo . We created a suite of plasmids that allow the expression of carboxy‐terminal sGFP fu...

Summary The nitrate conjugative element (NCE) encodes the ability to respire nitrate in the facultative Thermus thermophilus NAR1 strain. This process is carried out by two heterotetrameric enzymes that catalyse the oxidation of NADH (Nrc) and the reduction of nitrate (Nar), whose expression is activated by the NCE‐encoded transcription factors DnrS and DnrT. We report the presence of NCE in other facultative strains of T. the...