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Archive - Jul 31, 2019

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TB Mycobacteria Can Use Carbon Monoxide for Survival

Carbon monoxide is an infamous and silent killer that can cause death in minutes. But while it is deadly for us, some microorganisms actually thrive on it, by using this gas as an energy source. Associate Professor Chris Greening and his team of microbiologists from the School of Biological Sciences, Monash University in Australia have discovered that some pathogens depend on carbon monoxide to survive when other nutrients are not available. The research focused on mycobacteria, a bacterial group that causes killer diseases such as tuberculosis (TB), leprosy, and Buruli ulcer. During infection, these microbes are in a hostile environment with very few nutrients to go around, meaning that anything they can do to get extra energy can be hugely advantageous. "When microbial cells are starved of their preferred energy sources, one way they subsist is by scavenging gases such as carbon monoxide," said Monash PhD student Paul Cordero, the co-lead author of the study. "They breakdown this gas into its fundamental components, which provide the cells just enough energy to persist." The researchers showed that an enzyme called carbon monoxide dehydrogenase is what allows mycobacteria to obtain energy from this gas. While the energy gained is not enough to allow for growth, the researchers found that carbon monoxide consumption allowed mycobacteria to survive for longer periods of time. The study was published online on July 29,2019 in the ISME Journal. The open-access article is titled “Atmospheric Carbon Monoxide Oxidation Is a Widespread Mechanism Supporting Microbial Survival.” The group's findings suggest that Mycobacterium tuberculosis might be able to survive inside the human host by using carbon monoxide. Present in humans since ancient times, TB remains a major global health burden.

Study Reveals Intracellular Release Mechanism for ASCT2-Transportd Nutrient Amino Acid Glutamine; Study May Lay Groundwork for Development of Small Molecules to Inhibit Growth of Cancer Cells

In order to sustain fast growth, cancer cells need to take up nutrients at a faster rate than healthy cells. The human glutamine transporter ASCT2 allows the amino acid glutamine to enter cells and ASCT2 (image) is upregulated in many types of cancer cells, which need more glutamine. It is a potential target for new anti-cancer drugs. Researchers at the University of Groningen in the Netherlands have now elucidated a structure of the human ASCT2 that provides unprecedented insight into the workings of this protein, and may aid the development of drugs. The results were published in Nature Communications on July 31, 2019. The open-access article is titled “A One-Gate Elevator Mechanism for the Human Neutral Amino Acid Transporter ASCT2.” This work allowed the researchers to solve a long-lasting riddle. It was known that these transporters work like an elevator, where the substrate glutamine is engulfed by the protein, and then carried over a long distance through the cell membrane from the outside to the inside of the cell. While it was known how the substrate enters the elevator on the outside, it remained enigmatic what happens on the inside. This study now shows, for the first time, how the transported glutamine is released into the cytoplasm of the cell. The release mechanism is surprisingly similar to its catch mechanism on the outside of the cell. The same gate - a.k.a. elevator door - is used on either side of the membrane. "Hence, we have named the transport mechanism a 'one-gate elevator,” which sets it apart from the more commonly observed mechanisms that use two different gates for entry and release,” author Dr. Dirk Slotboom says. Senior author Dr. Cristina Paulino said, "This observation is of great fundamental interest, but also has potential implications for drug design.