The role of the alternative sigma factor PP4553 in the stress response of Pseudomonas putida

  • Autor:

    Bugert, B. / Overhage, J. (2011)

  • Quelle:

    ECAb 2011, Berlin, Deutschland, 25.-29. September, 2011

  • Datum: 2011
  • Bugert, B. / Overhage, J. (2011): „The role of the alternative sigma factor PP4553 in the stress response of Pseudomonas putida“. In: ECAb 2011, Berlin, Deutschland, 25.-29. September, 2011


Pseudomonas putida is a Gram-negative, aerobic, flagellated and non-pathogenic soil bacterium, which is well known for its extremely metabolic versatility. Because of this, P. putida offers a considerable potential for biotechnological applications and its use in bioremediation, biotransformation or plant protection, among others, is currently under investigation.

The remarkable versatility of this bacterium is at least in parts driven by sophisticated and coordinated regulation of gene expression mediated by a repertoire of transcriptional regulators, in particular the so called sigma factors. Sigma factors are essential for prokaryotic transcription initiation and enable specific binding of the RNA polymerase to the respective promoter recognition sites. Bacteria generally contain one predominant housekeeping sigma factor which controls most of the transcription during exponential growth and a pool of alternative sigma factors which are activated in response to different environmental and often stressful conditions.

The genome of P. putida exhibits with 24 a striking number of putative sigma factors in comparison to other biotechnological relevant bacteria like E. coli or C. glutamicum (both 7 putative sigma factors). To better understand these complex regulatory networks and to identify their involvement in biotechnological processes, we analyzed the specific gene expression of nine putative sigma factors (e.g. rpoH, rpoN, sigX, PP-ECF-10, etc.) using RT-PCR and reporter gene fusions (gfp, luxABCDE) under different, biotechnological relevant growth conditions like aromatic compound degradation, long term fermentation, or under oxidative stress, among others. Microarray and mutant analyses were performed to gain a deeper insight into the regulatory systems.