Sunday , January 24 2021

New metabolic mechanism in bacteria – Medical news



An international study, led by Spanish researchers, has found a new metabolic mechanism in bacteria

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Detail of the three-dimensional structure of the protein by atomic resolution / IRNASA

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Detail of the three-dimensional structure of the protein by atomic resolution / IRNASA

This is the first evidence that some of these microorganisms living in environments lacking light and oxygen use metabolic mechanisms that were considered unique to organisms performing photosynthesis. The foundation can help combat bacterial resistance to antibiotics.

An international research led by the Institute of Natural Resources and Agrobiology in Salamanca (IRNASA, CSIC Center) describes a new metabolic mechanism in bacteria. The result, published in the prestigious scientific journal Test of the National Academy of Sciences in the United States (PNAS) is the first evidence that some bacteria living in environments lacking light and oxygen can use metabolic mechanisms that were considered unique to organisms performing photosynthesis. In the biomedical field, this discovery opens a new way of combating the resistance of certain bacteria to antibiotics.

Living creatures produce the energy they need from food through a very complex network of biochemical reactions, which we as a whole call metabolism. The metabolic processes that occur in the cells are the basis of life on a molecular scale, from which the required energy is achieved, for example, to move, grow or reproduce among many other types of vital activities.

Also the type of metabolic reactions that occur in an organism's cells determines what types of substances will be nutritious to that organism and which will be toxic. For example, some bacteria use hydrogen sulfide as nutrients, but that gas is toxic to most animals. Likewise, the particular metabolism allowed by the plants allows them to live only from water and sunlight, which is impossible for animals.

This discovery opens a new way to combat the resistance of certain bacteria to antibiotics

Therefore, there are a variety of variants of the metabolic reactions that occur in living beings. In view of its relevance, the vast majority of metabolic processes have been investigated and characterized extensively in the last decades. However, it is still possible to find new varieties of metabolic processes in certain organisms.

An exclusive protein of anaerobic bacteria

Now, this study led by Mónica Balsera, IRNASA researcher, studied a new protein found exclusively in some anaerobic bacteria, that is, bacteria that live in environments that lack oxygen.

This protein is a chimeric of two different proteins that usually occur in separate metabolic pathways: on the one hand, the NADPH-dependent Thioredoxin Reductase (NTR) present in all known living organisms; and on the other hand, Tredoredoxin Reductase is dependent on Ferredoxin (FTR), which are solely photosynthetic organisms.

The resulting protein, called Ferredoxin-dependent Flavin-Thiorredoxin Reductase (FFTR), is special because it contains an unprecedented blend of the functionalities of the two initial proteins. On the one hand, it interacts with ferredoxin, as FTR does, and on the other hand, it uses the same binding module for a flavor factor like NTR.

This is the first evidence that some bacteria use metabolic mechanisms that are considered unique to photosynthetic organisms

As a result of this mix, a new protein with unique properties is generated, which is described in detail and for the first time in the work published in PNAS. To complete this study, it has been necessary to achieve the three-dimensional structure of the protein by nuclear solution obtained by high energy X-ray diffraction experiments produced in ALBA (Barcelona) and Diamond Synchronotron (Oxford, United Kingdom).

From a scientific point of view, the discovery is of enormous interest as this is the first evidence that some bacteria living in environments lacking oxygen where they are not exposed to light use metabolic mechanisms that were thought so far There were unique to photosynthetic organisms, such as algae and plants.

From the biomedical point of view, the study is even more relevant if possible because some of the bacteria in which this protein is found are extremely dangerous pathogens, including which are included Clostridium difficile. Clostridium botulinum and Clostridium tetani, causing pseudomembranous colitis, botulism and tetanus disease, respectively.

This conclusion therefore opens the door to the development of new approaches in the search for molecules with antibiotic activity, which is one of the most pressing public health problems currently due to the growing emergence of resistant and multiresistant bacteria accelerated in recent years. year due to abuse of antibiotics.


Bibliographic reference

A Ferrodoxin-Linked Flavoenzyme Fra? To the Family of Pyridine Nucleotide-Independent Thioredoxin Reductases. Rubén M Buey, David Fernández-Justel, José M de Pereda, José L Revuelta, Peter Schürmann, Bob B Buchanan and Mónica Balsera. Experiment for the American Academy of Sciences in the United States, 2018. https://doi.org/10.1073/pnas.1812781115


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