Charakterisierung des putativen Transkriptionsfaktors Roh von Enterobacter cloacae

Sebastian Franz Martin Häusler
2009
The development of resistance against antimicrobial compounds continues to pose new challenges to attending physicians. A phylogenetic old mechanism of resistance is provided by a system of bacterial drug export pumps. The pumps transport a wide overlapping spectrum of different agents. They are closely regulated by a broad range of transcription factors, for example in Escherichia coli MarA, Rob, or SoxS. In this study a new found putative transcription factor called Roh is investigated and
more » ... investigated and characterized. The term �Roh� is derived from �Rob homologue� due to the distinctive homology of the DNA sequence of Roh to the one of Rob, an already well described transcription factor in bacterial drug export systems. Roh was discovered by investigating the cause of differing minimal inhibiting concentrations (MICs) for ciprofloxacin of two closely related isolates of Enterobacter cloacae (Linde et al., 2002, JAC). The changed spectrum of resistance of the two strains as well as the increased expression of Roh suggested an activation of drug efflux systems by Roh. Experiments with �touch down� PCRs and Southern Blot analyses now confirm, that the sequence of Roh is existent in all investigated clinical isolates as well as in representative strains of the different clusters of the nomenspecies Enterobacter cloacae set up by H. Hoffmann (Hoffmann et al., 2003, AEM). In all isolates Roh appeares to be highly preserved in sequence. A roh-based phylogenetic tree could not be achieved. A high-copy plasmid pUC19-lacPR-roh-kana was generated for the overexpression of roh. With pUC19-lacPr-roh-kana transformed E. cloacae show increased MICs for typically by efflux pumps transported antibiotics but not for organic solvents or Cadmium ions being compared to wild type isolates. These findings suggest a role of Roh as transcription factor in the bacterial drug export system of Enterobacter cloa
doi:10.5283/epub.12225 fatcat:i3xrhxdrkvdbxf3echfo5fh3ce