Pseudomonas putida – a helper of plants and scientists and a cleaner of pollution… with the occasional mischief

What is Pseudomonas putida?

Pseudomonas putida is a bacterium that belongs to the family Pseudomonadaceae. It has a rod-like shape, poses flagella, hence is rather mobile and shows negative Gram staining. It lives in fresh water or in soil where the moisture is high enough.

Figure A. Pseudomonas putida (confocal micrscopy)
Figure B. Pseudomonas putida (cell culture)

Why is Pseudomonas putida important?

As a laboratory model – P. putida has the ability to degrade a wide variety of organic substances, which makes it a very useful laboratory model for studying different catabolic pathways.

For agriculture – Several strains colonize the roots of different plants and establish a relation known as “mutualism” in which both sides benefit from their relationship. The bacteria receive nutrients from the plant’s roots and in turn they protect them from pathogens by producing siderophores that are very effective against fungi. This increases the overall plant health and abundance.

For the ecology – P. putida, due to its ability to degrade a great number of organic compounds, is very useful for controlling certain important aspects of the air, soil and water pollution. A vivid example is its ability to degrade benzene, xylene and toluene, which are major pollutants coming from the use of gasoline. Another very impressive ability of P. putida is to degrade styrene. Yes, it eats Styrofoam! Well, it is a bit more complex than that – First Styrofoam should be converted to styrene oil, which is then provided to the bacteria. When the bacteria “eats” this oil, it produces Poly-3-hydroxyalkanoates (PHA). The PHA is produced by an enzyme called PHA synthase and is accumulated into the bacteria as an energy reserve. When PHA is harvested from the bacterial culture, it can be used for the production of a degradable, hence eco-friendly, equivalent to Styrofoam.

Figure C. Pseudomonas putida changing the morphology of the roots of A. thaliana
Figure D. Cups made of PAH (biodegradable plastic)

Can Pseudomonas putida be harmful?

While P. putida was declared to be a “safe bacteria” to be used for cloning of genes, there are a few recorded cases in which it caused chronic sinusitis and was found in the patients’ ears, noses and throats. In another case P. putida caused an outbreak of ulceration on the backs of rainbow trout.

Figure E. Rainbow trout with ulcerations

Key proteins of Pseudomonas putida, their role and how to obtain them for your research

2-hydroxymuconate tautomerase

The 2-hydroxymuconate tautomerase is an enzyme that belongs to the family of isomerases. In the bacteria Pseudomonas putida it is coded by the tdnL gene. The enzyme is a relatively small one with a length of 62 amino acids of the mature form. Its function is to catalyze the isomerization of 2-hydroxymuconate stereoselectively to 2-oxo-3-hexenedioate. In this particular instance such isomerization is called ketonization since a carboxyl group is transformed into a keto group. The tdnL protein is involved in the pathway of salicylate degradation, which is part of the metabolism of aromatic compounds.

(2Z,4E)-2-hydroxyhexa-2,4-dienedioate               
(3E)-2-oxohex-3-enedioate

How to get this protein for your research?

The easiest and most cost-efficient way is to order a recombinant 2-hydroxymuconate tautomerase. It commercially available for expression in at least 4 systems: E. coli, Yeast, Baculovirus and Mammalian cells. Since the price for customized protein expression in Baculovirus and Mammalian cells is quite high and since this protein is of bacterial origin, meaning that it would not require specific post translational modifications that are specific to eukaryotic cells, it is perfectly reasonable to have it expressed in E.coli. This option costs the least and delivers the protein the fastest.

Where from and how to order?

There are multiple suppliers of life sciences products that offer customized protein expression. All you need to provide to them is Uniprot number and/or the sequence of the protein, the preferred expression system, the preferred tag or if you’d like to have the protein in a tag-free form and to mention whether you would like to have the purified protein in a lyophilized of liquid form.

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