Ferri-bacillibactin uptake and hydrolysis in Bacillus subtilis.

Upon iron limitation, Bacillus subtilis secretes the catecholic trilactone (2,3-dihydroxybenzoate-glycine-threonine)3 siderophore bacillibactin (BB) for ferric iron scavenging. Here, we show that ferri-BB uptake is mediated by the FeuABC transporter and that YuiI, a novel trilactone hydrolase, catalyses ferri-BB hydrolysis leading to cytosolic iron release. Among several Fur-regulated ABC transport mutants, only DeltafeuABC exhibited impaired growth during iron starvation.

Sigma L is important for cold shock adaptation of Bacillus subtilis.

Although sigma factor-dependent transcriptional regulation was shown to be essential for adaptation to different environmental stimuli, no such sigma factor has been related to the regulation of the cold shock response in Bacillus subtilis. In this study, we present genetic evidence for participation of sigma(L) (sigma(54)) and the two sigma(L)-dependent transcriptional enhancers BkdR and YplP in the cold shock response of Bacillus subtilis JH642. Single-gene deletion of either sigL, bkdR, or yplP resulted in a cold-sensitive phenotype.

Inhibition of aryl acid adenylation domains involved in bacterial siderophore synthesis.

Aryl acid adenylation domains are the initial enzymes for aryl-capping of catecholic siderophores in a plethora of microorganisms. In order to overcome the problem of iron acquisition in host organisms, siderophore biosynthesis is decisive for virulence development in numerous important human and animal pathogens. Recently, it was shown that growth of Mycobacterium tuberculosis and Yersinia pestis can be inhibited in an iron-dependent manner using the arylic acyl adenylate analogue 5'-O-[N-(salicyl)-sulfamoyl] adenosine that acts on the salicylate activating domains, MbtA and YbtE [Ferreras JA, Ryu JS, Di Lello F, Tan DS, Quadri LEN (2005) Nat Chem Biol1, 29-32].

Cold-induced putative DEAD box RNA helicases CshA and CshB are essential for cold adaptation and interact with cold shock protein B in Bacillus subtilis.

The nucleic acid binding cold shock proteins (CSPs) and the cold-induced DEAD box RNA helicases have been proposed separately to act as RNA chaperones, but no experimental evidence has been reported on a direct cooperation. To investigate the possible interaction of the putative RNA helicases CshA and CshB and the CSPs from Bacillus subtilis during cold shock, we performed genetic as well as fluorescence resonance energy transfer (FRET) experiments. Both cshA and cshB genes could be deleted only in the presence of a cshB copy in trans, showing that the presence of one csh gene is essential for viability.

Genetic evidence for the temperature-sensing ability of the membrane domain of the Bacillus subtilis histidine kinase DesK.

A decrease in environmental temperature leads to the synthesis of Delta5-unsaturated fatty acids in Bacillus subtilis by the fatty acid desaturase Des. Des is regulated by the two-component system DesKR. To understand the mechanism of cold signal perception and transduction by the membrane domain and the cytosolic domain of DesK, we expressed the cytosolic domain of DesK in trans under the control of a xylose-inducible promoter without the membrane domain.

Genomewide transcriptional analysis of the cold shock response in Bacillus subtilis.

Previous studies with two-dimensional gel electrophoresis techniques revealed that the cold shock response in Bacillus subtilis is characterized by rapid induction and accumulation of two classes of specific proteins, which have been termed cold-induced proteins (CIPs) and cold acclimatization proteins (CAPs), respectively. Only recently, the B. subtilis two-component system encoded by the desKR operon has been demonstrated to be essential for the cold-induced expression of the lipid-modifying desaturase Des, which is required for efficient cold adaptation of the membrane in the absence of isoleucine.