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Scientists from CEITEC Masaryk University contributed to research revealing how resilient mycobacteria are able to adapt to different temperature conditions and survive in household environments or healthcare facilities.
Some of these bacteria are harmless, while others can cause infections and pose a serious health risk – especially to people with weakened immune systems. The researchers have now described in detail a regulatory mechanism that enables mycobacteria to adapt to environmental changes and survive in the long term.
Mycobacteria are a large group of bacteria that occur naturally in the environment and are characterised by a specific cell structure and high resistance. This genus includes pathogens that cause tuberculosis or leprosy, as well as non-tuberculous mycobacteria, which primarily cause infections in people with reduced immune defences and are therefore of long-term interest to biologists and medical researchers.
Microbiologists from the Faculty of Science at Charles University and the Institute of Microbiology of the Czech Academy of Sciences, led by Jarmila Hnilicová, studied in detail the function of the protein CarD in the non-tuberculous bacterium Mycobacterium smegmatis. CarD was already known to play an important role in switching genes on and off. However, it was not clear how the function of CarD itself was regulated. The researchers therefore systematically searched for additional molecules that physically bind to CarD or are part of the same regulatory system – and identified the protein CrsL. They found that CrsL not only influences CarD, but also helps mycobacteria cope with temperature fluctuations.
To understand the role of CrsL, which microbiologists had described using biological experiments, it was necessary to take a closer look at the proteins CarD and CrsL. At this stage of the research, the expertise of CEITEC MUNI played a key role, as it offered methods that allow regulatory molecules to be studied at the atomic level. What makes these approaches unique is that scientists can analyse proteins that lack a fixed structure – molecules that were until recently largely overlooked and whose study requires experiments tailored specifically to their properties. Using nuclear magnetic resonance, the researchers showed that CrsL belongs to this group of proteins, and at the same time described in detail how it binds to the regulatory protein CarD, which is crucial for controlling gene activity in mycobacteria.
“We found that CrsL modulates this interaction – meaning it subtly adjusts the way CarD cooperates with the cellular machinery responsible for switching genes on,” explained Martin Černý from CEITEC MUNI, one of the study’s first co-authors. “Describing the structure of CrsL and its interactions with other regulatory proteins allowed us to understand how bacteria switch genes on and off to survive temperature changes.”
At the atomic level, it thus becomes clear that bacteria have a highly sophisticated regulatory system that allows them to respond rapidly to changing environmental conditions. This detailed insight is essential for a broader understanding of why mycobacteria are able to survive in such diverse environments.
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The study of the CrsL protein also illustrates the importance of basic research and collaboration across scientific disciplines. The contribution of researchers from CEITEC Masaryk University falls within the field of structural biology – an area focused on understanding biological processes at their most fundamental level.
“Studying molecules at the atomic scale allows scientists to determine how individual molecules are organised within a cell and how they communicate with one another, helping us to understand behaviour of the bacterium,” added Lukáš Žídek, head of the research group at CEITEC MUNI specialising in protein structure and dynamics. “Our findings may significantly contribute to long-term efforts to reduce the risks associated with bacteria and their resistance to antibiotics.”
The study was published in the prestigious journal Nucleic Acids Research.
