Hexbyte Glen Cove How proteins help yeast adapt to changing conditions thumbnail

Hexbyte Glen Cove How proteins help yeast adapt to changing conditions

Hexbyte Glen Cove

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Proteins in the brain called prions are well known for their involvement in causing disease, but a study published today in eLife suggests they may help yeast cope with rapidly changing environmental conditions.

The findings show that prions may be part of an important epigenetic mechanism for controlling in changing conditions. Further insight into this role could aid our understanding of diseases that involve abnormal cell growth or .

Prions are proteins that are abnormally folded into different shapes. Prions can spread or be passed on to new cells. They have famously been linked to two deadly brain diseases, Creutzfeldt-Jakob and Mad Cow disease. But some prions can be helpful. Each shape of prion may perform a different task in the cell, in a similar way to a Swiss Army knife.

“While scientists have known about prions for decades, we don’t yet know what distinguishes beneficial prions from harmful ones,” says co-first author David Garcia, Ph.D., who was a postdoctoral fellow at the Department of Chemical Systems Biology at Stanford University School of Medicine, California, US, and is now Assistant Professor at the Institute of Molecular Biology, University of Oregon, US.

To learn more, Garcia and colleagues studied a yeast enzyme called pseudouridine synthase that can take on two . They found that, in its alter-ego prion form, this enzyme causes yeast to multiply and grow more quickly, although these changes come at the cost of a shorter lifespan for the yeast.

Through computer modelling, the team then showed that the changes brought about by the prion are beneficial when environmental resources are abundant, but harmful when resources are scarce. By reducing a so-called protein ‘chaperone’, they also showed that the prion can revert to its original enzyme shape. Since protein chaperones themselves fluctuate during changing conditions, they propose that this might be a way to turn the prion on or off when desirable.

“We’ve identified a new role for prions in which they can transform cell growth and survival,” says co-first author Edgar Campbell, a Ph.D. student in Chemical and Systems Biology at Stanford Medicine. “These findings suggest that prions may be another form of epigenetic control of cells.”

Epigenetic changes can alter the behaviour of cells without changing their DNA, can be passed on to new generations of cells, and may be turned on or off by environmental conditions. The authors suggest that learning more about the role of prions in epigenetic control may be critical to improving our understanding of prion diseases.

“These types of epigenetic changes are missed when we sequence genomes but can still have a major influence on cell growth,” concludes senior author Daniel Jarosz, Ph.D., Associate Professor of Chemical and Systems Biology and Developmental Biology at Stanford Medicine. “It is critical to learn more about the consequences of -driven epigenetic changes in and find new ways to search for them in yeast and other organisms.”



More information:
David M Garcia et al, A prion accelerates proliferation at the expense of lifespan, eLife (2021). DOI: 10.7554/eLife.60917

Journal information:
eLife



Citation:
How proteins help yeast adapt to changing conditions (2021, September 21)
retrieved 22 September 2021
from https://phys.org/news/2021-09-proteins-yeast-conditions.html

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Hexbyte Glen Cove Yeast and bacteria together biosynthesize plant hormones for weed control thumbnail

Hexbyte Glen Cove Yeast and bacteria together biosynthesize plant hormones for weed control

Hexbyte Glen Cove

Credit: CC0 Public Domain

Plants regulate their growth and development using hormones, including a group called strigolactones that prevent excessive budding and branching. For the first time, scientists led by UC Riverside have synthesized strigolactones from microbes. The work is published in the open-access journal, Science Advances.

Strigolactones also help form symbiotic relationships with microorganisms that allow the plant to absorb nutrients from the soil. These two factors have led to agricultural interest in using strigolactones to control the growth of weeds and root parasites, as well as improving nutrient uptake.

These root-extruding compounds don’t come without risks. They also stimulate germination of witchweeds and broomrapes, which can cause entire crops of grain to fail, making thorough research essential prior to commercial development. Scientists are still learning about the physiological roles played by this diverse group of hormones in . Until recently, manufacturing pure strigolactones for scientific study has been difficult and too costly for agricultural use.

“Our work provides a unique platform to investigate biosynthesis and evolution, and it lays the foundation for developing strigolactone microbial bioproduction processes as alternative sourcing,” said corresponding author Yanran Li, a UC Riverside assistant professor of chemical and environmental engineering.

Together with co-corresponding author Kang Zhou at National University Singapore, Li directed a group that inserted plant genes associated with strigolactone production into ordinary baker’s yeast and nonpathogenic Escherichia coli bacteria that together produced a range of strigolactones.

Producing strigolactones from yeast turned out to be very challenging. Although engineered yeast is known to modify the strigolactone precursor, called carlactone, it could not synthesize carlactone with any of the specific genes used by the researchers.

“This project started in early 2018, yet for over 20 months there was basically no progress. The gatekeeping enzyme DWRF27 is not functional no matter how we try in yeast,” Li said. “Kang developed a microbial consortium technique to produce a Taxol precursor in 2015 and that inspired this wonderful collaboration.”

The team turned toward E. coli, which had already been shown capable of producing carlactone. The carlactone it produced, however, was unstable and could not be further modified by engineered E. coli into any strigolactones. Li’s group managed to optimize and stabilize the carlactone precursor.

To their delight, when the yeast and bacteria were cultured together in the same medium, the E. coli and yeast worked as a team: E. coli made carlactone, and the yeast transformed it into various final strigolactone products. The method also produced enough strigolactones to extract and study. Using this platform, the group identified the function of multiple strigolactone , showing that sweet orange and grape have the potential to synthesize orobanchol-type strigolactones.

The team also engineered microbe metabolism to boost strigolactone production threefold to 47 micrograms per liter, enough for scientific study. Though commercial production of strigolactones is still a long way off, the new method for biosynthesizing them from a yeast-bacterium consortium will help scientists learn more about this important group of plant hormones, especially the enzymes involved.

Enzymes are protein catalysts and are responsible for modification of carlactone by yeast. Because carlactone is unstable, it cannot be purchased from commercial sources. As a result, many plant scientists have difficulty studying new enzymes that may work to transform carlactone into strigolactones.

“The new yeast-bacterium co-culture provides a convenient way for scientists to complete such works because the bacterium makes carlactone in situ,” Zhou said. “With discovery of more enzymes and optimization of the microbial consortium, we can manufacture strigolactones in quantity in the future.”

The paper is titled “Establishment of strigolactone-producing bacterium- consortium.”



More information:
Sheng Wu et al, Establishment of strigolactone-producing bacterium-yeast consortium, Science Advances (2021). DOI: 10.1126/sciadv.abh4048

Citation:
Yeast and bacteria together biosynthesi

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