Construction and Analysis of Two Genome-Scale Deletion Libraries for Bacillus subtilis.

A systems-level understanding of Gram-positive bacteria is important from both an environmental and health perspective and is most easily obtained when high-quality, validated genomic resources are available. To this end, we constructed two ordered, barcoded, erythromycin-resistance- and kanamycin-resistance-marked single-gene deletion libraries of the Gram-positive model organism, Bacillus subtilis. The libraries comprise 3,968 and 3,970 genes, respectively, and overlap in all but four genes.

MurJ and a novel lipid II flippase are required for cell wall biogenesis in Bacillus subtilis.

Bacterial surface polysaccharides are synthesized from lipid-linked precursors at the inner surface of the cytoplasmic membrane before being translocated across the bilayer for envelope assembly. Transport of the cell wall precursor lipid II in Escherichia coli requires the broadly conserved and essential multidrug/oligosaccharidyl-lipid/polysaccharide (MOP) exporter superfamily member MurJ. Here, we show that Bacillus subtilis cells lacking all 10 MOP superfamily members are viable with only minor morphological defects, arguing for the existence of an alternate lipid II flippase.

Vibrio cholerae LexA coordinates CTX prophage gene expression.

The filamentous bacteriophage CTX Phi transmits the cholera toxin genes by infecting and lysogenizing its host, Vibrio cholerae. CTX Phi genes required for virion production initiate transcription from the strong P(A) promoter, which is dually repressed in lysogens by the phage-encoded repressor RstR and the host-encoded SOS repressor LexA. Here we identify the neighboring divergent rstR promoter, P(R), and show that RstR both positively and negatively autoregulates its own expression from this promoter.

LexA represses CTXphi transcription by blocking access of the alpha C-terminal domain of RNA polymerase to promoter DNA.

CTXPhi is a Vibrio cholerae-specific temperate filamentous phage that encodes cholera toxin. CTXPhi lysogens can be induced with DNA damage-inducing agents such as UV light, leading to the release of CTXPhi virions and the rapid dissemination of cholera toxin genes to new V. cholerae hosts.

CTXphi and Vibrio cholerae: exploring a newly recognized type of phage-host cell relationship.

The genes encoding cholera toxin, one of the principal virulence factors of the diarrhoeal pathogen Vibrio cholerae, are part of the genome of CTXphi, a filamentous bacteriophage. Thus, CTXphi has played a critical role in the evolution of the pathogenicity of V. cholerae.