In their ongoing studies of how yeast (fungi) can infect a host and cause disease, a research team at the Life Sciences and Bioengineering Center at Worcester Polytechnic Institute (WPI) has made an unexpected discovery.
They found that yeast produce a hormone previously known to be made by plants, and that the presence of that hormone in sufficient quantity within the yeast's immediate environment triggers the fungal cells to become more infectious.
The WPI research team led by Reeta Prusty Rao, PhD, assistant professor of biology and biotechnology, working in collaboration with Jennifer Normanly, PhD, associate professor of biochemistry and molecular biology at the University of Massachusetts in Amherst, reported their findings in the paper "Aberrant synthesis of indole-3-acetic acid in Saccharomyces cerevisiae triggers morphogenic transition, a virulence trait of dimorphic pathogenic fungi" published in the May 2010 issue of the journal Genetics. The paper was featured in the "highlights" section of the journal, where the editors called it a "surprising finding."
"This is a well-known plant hormone. In fact, it was first described in plants by Charles Darwin in 1880," Prusty Rao said. "So we were surprised to see it made in yeast, and to see its impact on virulence traits of fungi that cause disease in people."
Commonly called baker's yeast or brewer's yeast, the fungus Saccharomyces cerevisiae (S. cerevisiae) does not cause human disease. It is, however, a model system for studying other fungi like Candida albicans (C. albicans) that do cause diseases like thrush and vaginal yeast infections, which affect millions of people each year and are not easily cleared by the handful of anti-fungal drugs currently available. While most fungal infections do not cause serious harm, if one spreads to the bloodstream it can be deadly. Hospitalized patients with catheters or central intravenous lines are at risk, as the fungi can grow on those devices and enter the body. Because of the lack of an effective treatment, the mortality rate for some systemic fungal infections is nearly 45 percent. Prusty Rao's lab explores the basic biology of yeast to better understand the processes of fungal infections and to identify potential targets for new drug development.
Before fungi begin to infect a host, they first undergo a dramatic physical change and grow filaments that look like twigs on a leafless tree. The hormone indole-3-acetic acid (IAA) regulates how plants grow, causing them to extend shoots towards sunlight. Previous work by Prusty Rao and others has shown that yeast take-up IAA from the environment to stimulate the growth of filaments. In the current study, Prusty Rao's team found that yeast also produce IAA themselves and secrete it into the environment around them. In this manner, the ongoing secretion and uptake of IAA presumably becomes a feedback loop giving the yeast information about the number of yeast nearby. If there are many yeast secreting IAA, then there is more in the environment to take up.
Furthermore, Prusty Rao's team found that when the concentration of IAA reached a certain threshold, the fungus began to change shape and grow filaments (see figure), providing "strong support" for a connection between the yeasts' production of IAA and fungal infection.
"If there is just one yeast cell sitting under your toe nail, then it won't be a problem—but if there are a thousand yeast cells there, then they can begin to filament and cause infection," Prusty Rao noted. "We believe the data show that IAA plays a role in the yeast's ability to know when there are sufficient numbers of them in close enough proximity to try and infect a host, be it a plant or a person."
About Worcester Polytechnic Institute
Founded in 1865 in Worcester, Mass., WPI was one of the nation's first engineering and technology universities. WPI's14 academic departments offer more than 50 undergraduate and graduate degree programs in science, engineering, technology, management, the social sciences, and the humanities and arts, leading to bachelor's, master's and PhD degrees. WPI's world-class faculty work with students in a number of cutting-edge research areas, leading to breakthroughs and innovations in such fields as biotechnology, fuel cells, information security, materials processing, and nanotechnology. Students also have the opportunity to make a difference to communities and organizations around the world through the university's innovative Global Perspective Program. There are more than 20 WPI project centers throughout North America and Central America, Africa, Australia, Asia, and Europe.
Michael Cohen | EurekAlert!
When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short
23.03.2017 | Institut für Pflanzenbiochemie
WPI team grows heart tissue on spinach leaves
23.03.2017 | Worcester Polytechnic Institute
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
23.03.2017 | Life Sciences
23.03.2017 | Power and Electrical Engineering
23.03.2017 | Earth Sciences