(ORDO NEWS) — A group of scientists from Cornell University used genetic engineering to better understand antibacterial therapies. To do this, they selected a molecule for the quantitative determination of protein. During the experiment, it turned out that bacteria have previously unknown protective properties.
For example, through a complex series of interactions, they can identify and then create resistance to toxic chemicals and metals such as silver and copper. It was previously believed that only antibiotics can create such a defense mechanism.
In the E.coli bacterium, the CusS protein of the sensor of the inner membrane is mobilized from the cluster form when copper ions are detected in the environment. CusS recruits the CusR transcriptional regulatory protein and then cleaves it to phosphorylate CusR, which then activates gene expression, helping the cell defend itself against toxic copper ions.
It turned out that bacterial resistance is actually the work of the tag team when two proteins work together inside the cell. A single protein (CusS) in the inner membrane detects the presence of a chemical or metal and sends a signal to a regulatory protein (CusR) in the cytosol or intercellular fluid. A regulatory protein binds to DNA and activates a gene that generates transport proteins that cleanse the cell of toxins.
As a rule, scientists analyze these functions using biochemical analyzes that remove protein from the cell. However, this process does not allow scientists to observe proteins in their natural environment, and some details, such as the spatial arrangement between proteins, remain unclear.
For a deeper analysis, the team of scientists used the visualization of individual cells, whereby they marked individual proteins in a live Escherichia coli with a fluorescent signal and displayed the proteins one at a time, tracking their movements. The procedure produced millions of images and, ultimately, a detailed, high-quality map of the movement of proteins.
The research team was especially interested in the activity of sensory proteins, which are of two types: those that come together, and those that move around the inner membrane. The researchers found that when E. coli collides with copper, the number of motile species of sensory proteins increases, and the proportion of clusters decreases.
Thus, it was found that mobilized sensory proteins interact with the regulatory protein and initiate a complex series – from copper binding to binding and splitting of compounds, which ultimately leads to gene expression. Under the influence of this process, the metal is completely washed out of the cell.
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