Lack of CbrB in Pseudomonas putida affects not only aminoacids metabolism but also different stress responses and biofilm development

Centro Andaluz de Biología del Desarrollo/ CSIC/ Universidad Pablo de Olavide, Carretera de Utrera, Km. 1. 41013 Seville, Spain.
Environmental Microbiology (Impact Factor: 6.2). 06/2010; 12(6):1748-61. DOI: 10.1111/j.1462-2920.2010.02254.x
Source: PubMed


The CbrAB two-component system has been described in certain species of Pseudomonads as a global regulatory system required for the assimilation of several amino acids (e.g. histidine, proline or arginine) as carbon or carbon and nitrogen sources. In this work, we used global gene expression and phenotypic analyses to characterize the roles of the CbrAB system in Pseudomonas putida. Our results show that CbrB is involved in coordination with the nitrogen control system activator, NtrC, in the uptake and assimilation of several amino acids. In addition, CbrB affects other carbon utilization pathways and a number of apparently unrelated functions, such as chemotaxis, stress tolerance and biofilm development. Based on these new findings, we propose that CbrB is a high-ranked element in the regulatory hierarchy of P. putida that directly or indirectly controls a variety of metabolic and behavioural traits required for adaptation to changing environmental conditions.

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    • "To further demonstrate that the CbrA sensor has the same function in both species, we swapped cbrA in the two species. We constructed PAO1DcbrA and KT2442DcbrA deletion mutants (PAO6862 and MPO413), and we tested their growth in BSM minimum medium supplemented with citrate, i.e. a carbon source that a cbrAB mutant is unable to utilize (Amador et al., 2010; Nishijyo et al., 2001). As expected, growth of both cbrA mutants was impaired in citrate, whilst Tn7 chromosomal insertion of cbrA from P. aeruginosa or P. putida, under the control of its own promoter (carried by pME10105 or pMPO1317, respectively), fully restored the growth of both mutants to the WT level (Fig. 3a, b). "
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    ABSTRACT: The Pseudomonads CbrA/B system is involved in the utilization of carbon sources and carbon catabolite repression (CCR) through the activation of the small RNAs crcZ in Pseudomonas aeruginosa, and crcZ and crcY in Pseudomonas putida. Interestingly, previous works reported that the CbrA/B system activity in P. aeruginosa PAO1 and P. putida KT2442 responds differently to the presence of different carbon sources, thus raising the question of the exact nature of the signal(s) detected by CbrA. Here, we demonstrate that the CbrA/B/CrcZ(Y) signal transduction pathway is similarly activated in the two Pseudomonas species. We show that the CbrA sensor kinase is fully interchangeable between the two species and, moreover, responds similarly to the presence of different carbon sources. In addition, a metabolomics analysis allowed supporting the hypothesis that CCR responds to the internal energy status of the cell, as the internal C/N ratio seems to determine CCR and non-CCR conditions. The strong difference found in the ratio 2-OG/Gln between CCR and non-CCR conditions points out to the close relationship between carbon and nitrogen availability, or the relationship between the CbrA/B and NtrB/C systems, suggesting that both regulatory systems sense the same sort or interrelated signal.
    Full-text · Article · Jul 2014 · Microbiology
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    • "In order to regulate the > 5000 genes encoded in its genome, P. putida is endowed with approximately 600 transcriptional factors and about 24 alternative sigma subunits of RNA polymerase (RNAP; Martinez-Bueno et al., 2002; dos Santos et al., 2004) that can give rise to a very complex gene expression landscape. But little is known on the functionally of the vast majority of these regulators because only few global factors have been investigated using transcriptomics or other wet approaches (Morales et al., 2006; Moreno et al., 2009; Amador et al., 2010; Herrera et al., 2010; Silva-Rocha et al., 2012). More recently, a list of candidate non-coding RNAs (ncRNAs) of P. putida has been generated (Frank et al., 2011), but again, not much information is available regarding the signals sensed by these and their cognate genomic targets. "
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    • "Other highly represented and cross-phylum conserved associations include the control of nitrogenase (VnfA, 11 phyla/classes), nitric oxide reduction (NorR), nitrogen assimilation and the production of EPS and LPS (NtrC), the transport and metabolism of (di-)carboxylates (AcoR, DctD, FhlA, GabR, PrpR), flagellar synthesis (AdnA, FleQ, FleR, FlrA, FlrC) and the degradation and uptake of various kinds of cell wall (poly-)saccharides (CelR- and LevR-like). Minor activities not listed include the sensing, transport and metabolism of hydrocarbons (XylR-like [42]), aromatic amino acids (PhhR [78] or CbrB [90]) and the production of the EPS alginate (AlgB [91]). "
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