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Normally our bodies harbour many bacteria that are beneficial
Bacteria in the human intestine contribute to supply vitamins to our bodies that otherwise would be difficult for us to produce.Some pathogeneic bacteria can cause diseases such as tuberculosis, pneumonia, etc.Our intestine contains a rich bacterial flora that is in equilibrium with itself and with our organism.
Pathogenic bacteria are not always dangerous, we need to be in a poor health condition, and the number of bacteria that invade our bodies has to be sufficiently large to cause an infection.Penicillin kills bacteria because it prevents them from correctly producing their envelope
When we suffer an infection our immune system tries to kill the pathogenic bacteria, but sometimes it is not sufficient and we need medication.An important advance in the treatment of infections was the discovery, in the first half of the 20th century, of antibiotics like penicillin.
The envelope of bacteria contains a rigid mesh formed by a molecule that is not found in the cells of our body.Peptidoglycan, the scientific name of the mesh, forms a layer called murein that surrounds the bacterial cell. Penicillin inhibitis the activity of some proteins that are required for the crosslinking of peptidoglycan .Penicillin is harmless for our cells because they do not contain peptidoglycan.
The use and misuse of antibiotics has contributed to the spread of antibiotic resistance to many bacteria, among them to dangerous pathogensPeptidoglycan molecules have been depicted as red rung ladder like structures. In rod shaped bacteria, like Escherichia coli, the peptidoglycan molecules can be added to elongate the rod (the horizontal ladder) or to divide the cell (the vertical ladder). Penicillin, by binding to Penicillin Binding Proteins (PBPs), inhibits the proper synthesis of both ladders. Penicillin-treated bacteria contain a feeble envelope and are prone to burst or be killed by the immune system.
New compounds to attack resistant pathogenic bacteria are urgently needed, and we should use them cautiously to avoid destroying their effectiveness.
By studying the building blocks used by bacteria to divide, and the mechanisms that time the production of the division septum, we will be in a much better position to obtain new antibacterial drugs. For example, any compound able to disrupt the interaction between two proteins needed for division will prevent bacterial proliferation. Such compounds may signal the road to the discovery of a new antibiotic.
Targets for new antimicrobials to inhibit bacterial proliferation. We have identified some new targets that could be blocked to curb bacterial proliferation. These targets are found in some cell division proteins (black background spheres).
Some of the division proteins are also in contact with proteins (the group of coloured spheres at the top) that synthesise the murein layer (represented as small red spheres and rungs).
This work can be exploited to select or design inhibitors (depicted as an ideal red antibiotic tablet) that could work either by inhibiting protein activities or by preventing the interaction between different components of the division machinery.
This artist rendering is a cartoon and is not drawn to scale
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last update: 24 April 2000
