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In Vitro and In Vivo Bacteriolytic Activities of Escherichia coli Phages: Implications for Phage Therapy. Sandra Chibani-Chennoufi, 2004.Four T4-like coliphages with broad host ranges for diarrhea-associated Escherichia coli serotypes were isolated from stool specimens from pediatric diarrhea patients and from environmental water samples . All four phages showed a highly efficient gastrointestinal passage in adult mice when added to drinking water . Viable phages were recovered from the feces in a dose-dependent way . The minimal oral dose for consistent fecal recovery was as low as 103 PFU of phage per ml of drinking water . In conventional mice, the orally applied phage remained restricted to the gut lumen, and as expected for a noninvasive phage, no histopathological changes of the gut mucosa were detected in the phage-exposed animals . E . coli strains recently introduced into the intestines of conventional mice and traced as ampicillin-resistant colonies were efficiently lysed in vivo by phage added to the drinking water . Likewise, an in vitro phage-susceptible E . coli strain freshly inoculated into axenic mice was lysed in vivo by an orally applied phage, while an in vitro-resistant E . coli strain was not lysed . In contrast, the normal E . coli gut flora of conventional mice was only minimally affected by oral phage application despite the fact that in vitro the majority of the murine intestinal E . coli colonies were susceptible to the given phage cocktail . Apparently, the resident E . coli gut flora is physically or physiologically protected against phage infection . Linear Plasmid in the Genome of Clavibacter michiganensis subsp . sepedonicus. Susan E. Brown, 2002.Contour-clamped homogeneous electric field gel analysis of genomic DNA of the plant pathogen Clavibacter michiganensis subsp . sepedonicus revealed the presence of a previously unreported extrachromosomal element . This new element was demonstrated to be a linear plasmid . Of 11 strains evaluated, all contained either a 90-kb (pCSL1) or a 140-kb (pCSL2) linear plasmid . Protein-Protein Interactions That Regulate the Energy Stress Activation of  B in Bacillus subtilis.Olivier Delumeau, 2002. B is an alternative
factor that controls the general stress response in Bacillus subtilis . In the absence of stress,
B is negatively regulated by anti- factor RsbW . RsbW is also a protein kinase which can phosphorylate RsbV . When cells are stressed, RsbW binds to unphosphorylated RsbV, produced from the phosphorylated form of RsbV by two phosphatases (RsbU and RsbP) which are activated by stress . We now report the values of the Km for ATP and the Ki for ADP of RsbW (0.9 and 0.19 mM, respectively), which reinforce the idea that the kinase activity of RsbW is directly regulated in vivo by the ratio of these nucleotides . RsbW, purified as a dimer, forms complexes with RsbV and
B with different stoichiometries, i.e., RsbW2-RsbV2 and RsbW2-B1 . As determined by surface plasmon resonance, the dissociation constants of the RsbW-RsbV and RsbW-B interactions were found to be similar (63 and 92 nM, respectively) . Nonetheless, an analysis of the complexes by nondenaturing polyacrylamide gel electrophoresis in competition assays suggested that the affinity of RsbW2 for RsbV is much higher than that for
B . The intracellular concentrations of RsbV, RsbW (as a monomer), and
B measured before stress were similar (1.5, 2.6, and 0.9 µM, respectively) . After ethanol stress they all increased . The increase was greatest for RsbV, whose concentration reached 13 µM, while those of RsbW (as a monomer) and
B reached 11.8 and 4.9 µM, respectively . We conclude that the higher affinity of RsbW for RsbV than for
B, rather than a difference in the concentrations of RsbV and
B, is the driving force that is responsible for the switch of RsbW to unphosphorylated RsbV .
Roles of the C-Terminal End of SecY in Protein Translocation and Viability of Escherichia coli. Kazuhiko Chiba, 2002.
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