Metabolic role of aldehyde dehydrogenases in
            Pseudomonas putida
            KT2440

Bacteria must be able to cope with harsh environments to survive. In Gram-negative bacteria like Pseudomonas species, resistance-nodulation-division (RND) transporters contribute to this task by pumping toxic compounds out of cells. Previously, we found that the RND system TtgABC of Pseudomonas putida KT2440 confers resistance to toxic metal chelators of the bipyridyl group. Here, we report that the incubation of a ttgB mutant in medium containing 2,2’-bipyridyl generated revertant strains able to grow in the presence of this compound. This trait was related to alterations in the pp_2827 locus (homolog of mexS in Pseudomonas aeruginosa). The deletion and complementation of pp_2827 confirmed the importance of the locus for the revertant phenotype. Furthermore, alteration in the pp_2827 locus stimulated expression of the mexEF-oprN operon encoding an RND efflux pump. Deletion and complementation of mexF confirmed that the latter system can compensate the growth defect of the ttgB mutant in the presence of 2,2’-bipyridyl. To our knowledge, this is the first report on a role of pp_2827 (mexS) in the regulation of mexEF-oprN in P. putida KT2440. The results expand the information about the significance of MexEF-OprN in the stress response of P. putida KT2440 and the mechanisms for coping with bipyridyl toxicity.

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Pumping iron to keep fit: modulation of siderophore secretion helps efficient aromatic utilization in Pseudomonas putida KT2440

Microbiology ◽

10.1099/mic.0.079277-0 ◽

2014 ◽

Vol 160 (7) ◽

pp. 1393-1400 ◽

Cited By ~ 9

Author(s):

Hiren Joshi ◽

Rachna Dave ◽

V. P. Venugopalan

Keyword(s):

Pseudomonas Putida ◽

Compensatory Mechanism ◽

Limited Information ◽

Pseudomonas Putida Kt2440 ◽

Physiological Factors ◽

Aromatic Substrates ◽

Iron Assimilation ◽

Key Factor ◽

Alternative Carbon Source

Studies of biotechnology applications of Pseudomonas putida KT2440 have been predominantly focused on regulation and expression of the toluene degradation (TOL) pathway. Unfortunately, there is limited information on the role of other physiological factors influencing aromatic utilization. In this report, we demonstrate that P. putida KT2440 increases its siderophore secretion in response to the availability of benzyl alcohol, a model aromatic substrate. It is argued that accelerated siderophore secretion in response to aromatic substrates provides an iron ‘boost’ which is required for the effective functioning of the iron-dependent oxygenases responsible for ring opening. Direct evidence for the cardinal role of siderophores in aromatic utilization is provided by evaluation of per capita siderophore secretion and comparative growth assessments of wild-type and siderophore-negative mutant strains grown on an alternative carbon source. Accelerated siderophore secretion can be viewed as a compensatory mechanism in P. putida in the context of its inability to secrete more than one type of siderophore (pyoverdine) or to utilize heterologous siderophores. Stimulated siderophore secretion might be a key factor in successful integration and proliferation of this organism as a bio-augmentation agent for aromatic degradation. It not only facilitates efficient aromatic utilization, but also provides better opportunities for iron assimilation amongst diverse microbial communities, thereby ensuring better survival and proliferation.

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Role of iron and the TonB system in colonization of corn seeds and roots by Pseudomonas putida KT2440

Environmental Microbiology ◽

10.1111/j.1462-2920.2005.00720.x ◽

2005 ◽

Vol 7 (3) ◽

pp. 443-449 ◽

Cited By ~ 31

Author(s):

Maria Antonia Molina ◽

Patricia Godoy ◽

Maria Isabel Ramos-Gonzalez ◽

Nuria Munoz ◽

Juan L. Ramos ◽

...

Keyword(s):

Pseudomonas Putida ◽

Pseudomonas Putida Kt2440 ◽

Tonb System

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Intracellular 2-keto-3-deoxy-6-phosphogluconate is the signal for carbon catabolite repression of phenylacetic acid metabolism in Pseudomonas putida KT2440

Microbiology ◽

10.1099/mic.0.027060-0 ◽

2009 ◽

Vol 155 (7) ◽

pp. 2420-2428 ◽

Cited By ~ 13

Author(s):

Juhyun Kim ◽

Jinki Yeom ◽

Che Ok Jeon ◽

Woojun Park

Keyword(s):

Pseudomonas Putida ◽

Transcriptional Repression ◽

Catabolite Repression ◽

Phenylacetic Acid ◽

Carbon Catabolite Repression ◽

Transcriptional Level ◽

Pseudomonas Putida Kt2440 ◽

Coa Ligase ◽

Additional Support

The growth pattern of Pseudomonas putida KT2440 in the presence of glucose and phenylacetic acid (PAA), where the sugar is used in preference to the aromatic compound, suggests that there is carbon catabolite repression (CCR) of PAA metabolism by glucose or gluconate. Furthermore, CCR is regulated at the transcriptional level. However, this CCR phenomenon does not occur in PAA-amended minimal medium containing fructose, pyruvate or succinate. We previously identified 2-keto-3-deoxy-6-phosphogluconate (KDPG) as an inducer of glucose metabolism, and this has led to this investigation into the role of KDPG as a signal compound for CCR. Two mutant strains, the edd mutant (non-KDPG producer) and the eda mutant (KDPG overproducer), grew in the presence of PAA but not in the presence of glucose. The edd mutant utilized PAA even in the presence of glucose, indicating that CCR had been abolished. This observation has additional support from the finding that there is high phenylacetyl-CoA ligase activity in the edd mutant, even in the presence of glucose+PAA, but not in wild-type cells under the same conditions. Unlike the edd mutant, the eda mutant did not grow in the presence of glucose+PAA. Interestingly, there was no uptake and/or metabolism of PAA in the eda mutant cells under the same conditions. Targeted disruption of PaaX, a repressor of the PAA operon, had no effect on CCR of PAA metabolism in the presence of glucose, suggesting that there is another transcriptional repression system associated with the KDPG signal. This is the first study to demonstrate that KDPG is the true CCR signal of PAA metabolism in P. putida KT2440.

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Plant growth promotion by Pseudomonas putida KT2440 under saline stress: role of eptA

Applied Microbiology and Biotechnology ◽

10.1007/s00253-020-10516-z ◽

2020 ◽

Vol 104 (10) ◽

pp. 4577-4592 ◽

Cited By ~ 2

Author(s):

Stefanie B. Costa-Gutierrez ◽

María Jesús Lami ◽

María Carolina Caram-Di Santo ◽

Ana M. Zenoff ◽

Paula A. Vincent ◽

...

Keyword(s):

Plant Growth ◽

Pseudomonas Putida ◽

Plant Growth Promotion ◽

Growth Promotion ◽

Saline Stress ◽

Pseudomonas Putida Kt2440

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Transcriptome Changes in Pseudomonas putida KT2440 during Medium-Chain-Length Polyhydroxyalkanoate Synthesis Induced by Nitrogen Limitation

International Journal of Molecular Sciences ◽

10.3390/ijms22010152 ◽

2020 ◽

Vol 22 (1) ◽

pp. 152

Author(s):

Dorota Dabrowska ◽

Justyna Mozejko-Ciesielska ◽

Tomasz Pokój ◽

Slawomir Ciesielski

Keyword(s):

Chain Length ◽

Nitrogen Limitation ◽

Stringent Response ◽

Wild Type ◽

Pseudomonas Putida Kt2440 ◽

Medium Chain ◽

Environmental Stimuli ◽

Medium Chain Length ◽

In The Wild

Pseudomonas putida’s versatility and metabolic flexibility make it an ideal biotechnological platform for producing valuable chemicals, such as medium-chain-length polyhydroxyalkanoates (mcl-PHAs), which are considered the next generation bioplastics. This bacterium responds to environmental stimuli by rearranging its metabolism to improve its fitness and increase its chances of survival in harsh environments. Mcl-PHAs play an important role in central metabolism, serving as a reservoir of carbon and energy. Due to the complexity of mcl-PHAs’ metabolism, the manner in which P. putida changes its transcriptome to favor mcl-PHA synthesis in response to environmental stimuli remains unclear. Therefore, our objective was to investigate how the P. putida KT2440 wild type and mutants adjust their transcriptomes to synthesize mcl-PHAs in response to nitrogen limitation when supplied with sodium gluconate as an external carbon source. We found that, under nitrogen limitation, mcl-PHA accumulation is significantly lower in the mutant deficient in the stringent response than in the wild type or the rpoN mutant. Transcriptome analysis revealed that, under N-limiting conditions, 24 genes were downregulated and 21 were upregulated that were common to all three strains. Additionally, potential regulators of these genes were identified: the global anaerobic regulator (Anr, consisting of FnrA, Fnrb, and FnrC), NorR, NasT, the sigma54-dependent transcriptional regulator, and the dual component NtrB/NtrC regulator all appear to play important roles in transcriptome rearrangement under N-limiting conditions. The role of these regulators in mcl-PHA synthesis is discussed.

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