In vivo imaging reveals the binding sites of theonellamide (TNM), a novel antifungal agent. The upper panels show a differential interference contrast micrograph of a yeast cell (left) and a fluorescent image of the cell stained with the membrane probe filipin (right), where the brightness indicates filipin binding at the cell membrane. The lower panels show a fluorescent image of a cell stained with TNM (left) and a merged image (right) of the cell labeled with TNM (red) and stained with filipin (green).
Now, researchers led by Minoru Yoshida from the RIKEN Advanced Science Institute in Wako have characterized the biological properties of theonellamide (TNM), an antifungal natural product isolated from marine sponges1. They found that, unlike typical modes of action, TNM specifically targets ergosterol lipid molecules in fungal cell membranes, not proteins. This bonding interaction rapidly activates a protein called Rho1 to over-produce 1,3-â-D-glucan sugar chain molecules—a process that forms an aberrant fungal cell wall. This unique mechanism promises to spur development of innovative antifungal agents. “We believe that TNM is the first compound that activates membrane signaling molecules by binding to a lipid,” says Yoshida.
Despite previous efforts to identify TNM’s specific biological actions, its sub-cellular targets were unknown until now. Yoshida and colleagues used a yeast complex to generate nearly 5,000 ‘open reading frames’ (ORFs), which are long strands of DNA that can encode proteins. This was to screen for sequences with altered susceptibility to TNM—so-called ‘hit genes’. Extensive bioinformatic analysis of the chemical-genomic profiles showed that the hit genes showed traits related to sterol binding, Rho-type protein activation or inhibition, and 1,3-â-D-glucan synthesis. However, none of the hit genes showed any physical interaction with TNM, demonstrating that proteins were not the primary target of this molecule.
By synthesizing fluorescently labeled TNM derivatives and comparing their in vivo localization to filipin molecules—known membrane-binding compounds—the team discovered that TNM directly targets ergosterol and related sterols in fungal cell membranes (Fig. 1). Attachment of TNM to these lipid molecules enhanced 1,3-â-D-glucan synthesis—but only in the presence of Rho1, confirming the unprecedented signaling behavior. Further experiments on Rho1 mutants determined that TNM can independently lower membrane integrity, gradually inducing lesions into the cellular structure.
The researchers’ next task—unraveling the complex mechanisms of TNM-induced membrane signaling—may throw light on how to avoid unwanted side-effects in humans during antifungal treatments. “TNM binds to not only ergosterol but also cholesterol, a mammalian counterpart,” explains Yoshida. “Our preliminary findings show that mammalian cells rapidly and transiently change morphology upon TNM treatment—making this compound a fabulous tool to dissect the function of membrane sterols in general.”
gro-pr | Research asia research news
At last, butterflies get a bigger, better evolutionary tree
16.02.2018 | Florida Museum of Natural History
New treatment strategies for chronic kidney disease from the animal kingdom
16.02.2018 | Veterinärmedizinische Universität Wien
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
Let’s say the armrest is broken in your vintage car. As things stand, you would need a lot of luck and persistence to find the right spare part. But in the world of Industrie 4.0 and production with batch sizes of one, you can simply scan the armrest and print it out. This is made possible by the first ever 3D scanner capable of working autonomously and in real time. The autonomous scanning system will be on display at the Hannover Messe Preview on February 6 and at the Hannover Messe proper from April 23 to 27, 2018 (Hall 6, Booth A30).
Part of the charm of vintage cars is that they stopped making them long ago, so it is special when you do see one out on the roads. If something breaks or...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
16.02.2018 | Information Technology
16.02.2018 | Health and Medicine
16.02.2018 | Physics and Astronomy