Genetic competence

R. P. Huang, and R. N. Reusch (1995). Genetic competence in Escherichia coli requires poly-beta-hydroxybutirate calcium polyphosphate membrane complex and certain divalent cations. J. 

Figure 9. A. Thermotropic fluorescence spectra of E. coli DH1 cells using the hydrophobic probe, N-phenyl-1 -naphthylamine (NPN). (a) Mid-log phase cells (b) stationary phase cells (c) cells made genetically transformable by the method of Hanahan.146 NPN was added to 4 mL of cell culture to a final concentration of 1 pM and the thermotropic fluorescence spectra were recorded.24 Measurements were made at increasing temperature (ca. 2 °C per min). Excitation 360 nm emission 410 nm. Measurements were made at increasing temperature (ca. 2 °C per min). B. Effects of physical treatments on the thermotropic transitions in genetically competent E. coli DH1. (a) Thermotropic transitions at descending temperature (b) cells pelleted at low speed and suspended in supernatant (c) as in b but suspended in equal volume of distilled water (d) as in (b) but suspended in 10 mM phosphate buffer, pH 7.4. Excitation 360 nm emission 410 nm. Fluorescent probe was NPN. Measurement (a) was made at decreasing temperature and (b), (c), (d) at increasing temperatures (ca. 2 °C per min).

The ability of E. coli PHB/polyP complexes to form calcium-selective channels in planar bilayers was investigated in the planar bilayer system described above (Figure 5). E. coli DH5a cells were made genetically competent to increase the concentration of PHB/polyP in the membranes. Then vesicles were prepared from the cell envelopes, and added to the cis side of a planar bilayer formed by synthetic 16 0, 18 1 PC between symmetric bathing solutions of 250 mM CaCl2, 5 mM MgCl2,10 mM Tris Hepes, pH 7.3. The complexes were allowed to insert spontaneously into the bilayer.27 No activity was observed in the absence of an applied... 

PHB/polyP complexes were first discovered in genetically competent bacteria.22 Although the complexes are present in the plasma membranes of log-phase cells of diverse organisms, their concentrations are low under optimal growth conditions. 

E. CoU innerMfopribranewhen genetically competent (caused by Ca Eulaayollc oigamsms highest concentration in gM rfionpIria... 

D Souza C, Nakano MM, Zuber P. Identification of comS, a gene of the srfA operon that regulates the establishment of genetic competence in Bacillus subtiiis. Proc Natl Acad Sci USA 1994 91 9397-9401. 

D Souia C, Nakano MM, Frisby DL, Zuber P. Translation of the open reading frame encoded by eomS, a gene of the srf operon, is necessary for the development of genetic competence but not surfactin biosynthesis in Bacillus subtib s. J Bacteriol 1995 177 4144-4148. 

Dubnau K, Roggianni M, Growth medium-independent genetic competence mutants of Bacillus subtiiis. J Bacteriol 1990 172 4048-4055. 

Kong L, Siranosian KJ, Grossman AD, Dubnau D. Sequence and properties of mecA A negative regulator of genetic competence in Bacillus subiilis. Mol Microbiol 1993 9 365-373. 

Reusch, R. N. and Sadoff, H. L. (1983). D-(-)-poly-beta-hydroxybutyrate in membranes of genetically competent bacteria. Journal of Bacteriology 156(2),... 

Grossman AD (1995) Genetic networks controlling the initiation of sporulation and the development of genetic competence in Bacillus subtilis. Annu Rev... 

Lindum PW, Anthoni U, Christophersen C, Eberl L, Molin S, Givskov M (1998) N-Acyl-L-homoserine lactone autoinducers control production of an extracellular lipopeptide biosurfiictant required for swarming motility of Serratia liquefaciens MGl. J Bacteriol 180 6384r-6388 Liu L, Nakano MM, Lee OH, Zuber P (1996) Plasmid-amplified comS enhances genetic competence and suppresses sinR in Bacillus subtilis. J Bacteriol 178 5144-5152... 

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