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The tra Region of the Conjugative Plasmid pIP501 Is Organized in an Operon with the First Gene Encoding the Relaxase. Brigitta Kurenbach, 2002.The tra genes orf1 to orf11 of pIP501 were shown to be transcribed as a single operon of 11.3 kb in Enterococcus faecalis by reverse transcription-PCR . The transcriptional start site of the tra mRNA was mapped at 110 bp upstream from the predicted TTG start codon of the first gene of the operon, the traA relaxase . The TraA protein (660 amino acids) and a C-terminally truncated version of the TraA protein (293 amino acids) were purified as fusions with glutathione S-transferase . oriT cleavage activity of both TraA proteins was demonstrated in vitro on supercoiled plasmid pVA2241 DNA containing oriTpIP501 . The activity of the DNA relaxase TraA is strictly dependent on the presence of Mg2+ or Mn2+ and is highest at temperatures of between 42 and 45°C . Tethering of the Bacillus subtilis  E Proprotein to the Cell Membrane Is Necessary for Its Processing but Insufficient for Its Stabilization.Jingliang Ju, 2003. E, a sporulation-specific transcription factor of Bacillus subtilis, is synthesized as an inactive proprotein with a 27-amino acid extension at its amino terminus . This "pro" sequence is removed by a developmentally regulated protease, but when present, it blocks
E activity, tethers
E to the bacterium's cytoplasmic membrane, and promotes
E stability . To investigate whether pro-E processing and/or stabilization are tied to membrane sequestration, we used fluorescent protein fusions to examine the membrane binding of SigE variants . The results are consistent with membrane association as a prerequisite for pro-E processing but not as a sufficient cause for the proprotein's stability .
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