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
International team discovers novel Alzheimer's disease risk gene among Icelanders
24.10.2016 | Baylor College of Medicine
New bacteria groups, and stunning diversity, discovered underground
24.10.2016 | DOE/Lawrence Berkeley National Laboratory
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
24.10.2016 | Power and Electrical Engineering
24.10.2016 | Life Sciences
24.10.2016 | Life Sciences