Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study yields insights into pathogenic fungi—and beer

08.08.2005


Chemotherapy and organ transplantation not only take a huge toll on patients, but they can compromise the immune system and leave patients vulnerable to infections from microbes such as pathogenic fungi--the fastest-growing cause of hospital-acquired infections. Now researchers from Whitehead Institute for Biomedical Research have discovered one possible reason why these fungal microbes are such a scourge.



According to the research appearing in the August 7 online edition of the journal Nature Genetics, fungal microbes can quickly alter the appearance of their cell surfaces, their "skin," disguising themselves in order to slip past the immune system’s vigilant defenses. And, for all the world’s brewers, the study also helps explain why certain beers are cloudy and others are clear.

"It’s all about skin," says Whitehead Member Gerald Fink, who compares the fungal microbe to an M&M--a sugar coating encasing the cell’s DNA. "The skin of fungi microbes is what enables them to stick to your organs, and thus become pathogenic. It also enables the fungi to stick together, which is desirable for fermentation in beer."


The genetic core to this study is a DNA phenomenon known as tandem repeats. Here, small units of between 3 and 200 nucleotides form within a gene and repeat sometimes up to about 35 times. (Nucleotides, the building blocks of our genome, are represented by the letters A, C, T, G.) In humans, these tandem repeats received a lot of attention when the gene responsible for Huntington’s disease was discovered; a repeat of the letters CAG in a gene called IT-15 causes the condition.

These tandem repeats also occur in fungal microbes. Kevin Verstrepen, a post-doctoral researcher in Fink’s lab, decided to find out how often they occur, and what possible functions they might offer, by using baker’s yeast as a model. Verstrepen scanned the entire yeast genome with a custom computer program developed by Whitehead’s bioinformatics group. He discovered that these repeats are common throughout the yeast genome, and that more than 60 percent occur in genes that code for cell-surface, or skin, proteins. In other words, "most of these repeats somehow affect how the yeast cell interacts with the environment surrounding it," says Verstrepen.

In addition, he found that the length of these repeats varied greatly between a mother and a daughter cell. While one yeast cell might have a 20-unit repeat on a particular gene, when it divides, the new cell might have only a five-unit repeat on that same gene. And subsequently, when that cell then divides, its daughter cell might go back to 20 repeats. "It’s like an accordion," says Verstrepen. "Our study really showed how quickly and easily these repeats can recombine, altering the properties of the cell surface almost immediately."

This provides a significant clue into why fungal infections can often be so deadly. The immune system generally recognizes invaders by certain signatures on their outer coatings, such as protein conformations. However, if these fungal microbes can quickly change the shape of these proteins by changing the number of repeats in the corresponding gene, they can then manage to stay one step ahead of our body’s defenses.

"It’s important to remember," says Fink, "that these microbes have been around for billions of years. They haven’t come this far without learning how to fight off predators."

Verstrepen and his colleagues took this research a step further, focusing on a gene called FLO1, a cell-surface gene common to both baker’s yeast and pathogenic fungi. FLO1 creates the conditions that enable yeast cells to adhere to surfaces. It’s also the gene that allows pathogenic fungi to stick to host tissue. The researchers discovered a clear correlation between the number of repeats in FLO1 and the degree to which these cells could adhere to a surface. When FLO1 contained many repeats, it adhered vigorously to a plastic surface. As the number of repeats declined, so did its ability to adhere.

Fink believes that these findings show why traditional approaches to targeting drugs won’t work on fungal microbes. The features that drugs target may be exactly the ones that change so readily. "We need to target other aspects to the cell surface that don’t change," says Fink, suggesting that certain sugar molecules residing on the inside of the cell coating may be valuable targets.

The research also may help to reveal why certain strains of yeast brew better beers.

Both Verstrepen and Fink have consulted for a number of commercial brewers. "Brewers have been cultivating certain strains of yeast for hundreds of years," says Fink. "The secret of a good, fresh, clear beer--the kind that Americans tend to like--is that the yeast cells all stick together." When yeast cells don’t adhere, the beer tends to cloud up. "We now know that these tandem repeats are the molecular mechanism that yields good beer."

David Cameron | EurekAlert!
Further information:
http://www.wi.mit.edu

More articles from Studies and Analyses:

nachricht Multi-year study finds 'hotspots' of ammonia over world's major agricultural areas
17.03.2017 | University of Maryland

nachricht Diabetes Drug May Improve Bone Fat-induced Defects of Fracture Healing
17.03.2017 | Deutsches Institut für Ernährungsforschung Potsdam-Rehbrücke

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

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...

Im Focus: Tracing down linear ubiquitination

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...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

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...

Im Focus: Researchers Imitate Molecular Crowding in Cells

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...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

NASA examines Peru's deadly rainfall

24.03.2017 | Earth Sciences

What does congenital Zika syndrome look like?

24.03.2017 | Health and Medicine

Steep rise of the Bernese Alps

24.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>