Login

GPC Members Login
If you have any problems or have forgotten your login please contact [email protected]


Hacking evolution, screening technique may improve most widespread enzyme

Plants evolved over millions of years into an environment that has dramatically changed in the last 150 years since the Industrial Revolution began: carbon dioxide levels have increased 50 percent, and the average global temperature has increased by nearly 2 degrees Fahrenheit. While natural adaptation has been unable to keep up, scientists have developed tools to simulate millions of years of evolution in days to help plants adapt.

In a new study published in the Journal of Biological Chemistry, researchers report a novel screening strategy that enabled them to identify, for the first time, a much more efficient form of the enzyme Rubisco, which catalyzes the first step of fixing carbon dioxide en route to creating plant biomass in photosynthesis.

"Although the most abundant and arguably the most important enzyme on our plant, Rubisco may not have been evolution's finest moment. Rubisco evolved when oxygen was absent from the atmosphere, and as a result, it was not forced to learn to differentiate between life-sustaining carbon dioxide molecules and oxygen molecules that create a toxic compound that costs the plant energy to recycle," said Don Ort, Deputy Director of Realizing Increased Photosynthetic Efficiency (RIPE), which supported this work. Ort is a physiologist with the USDA/ARS Photosynthesis Research Unit and the Robert Emerson Professor of Plant Biology and Crop Sciences at the Carl R. Woese Institute for Genomic Biology at the University of Illinois.

"We've shown that we can improve Rubisco's efficiency, its ability to differentiate carbon dioxide from oxygen --that's the real buzz," said lead author Spencer Whitney, an associate professor at the Australian National University. "Our Rubisco is faster and has a higher affinity for carbon dioxide. In the past, this determination took about two weeks, but our new screening system cut that time more than in half."

Using directed evolution, often described as evolution in a test tube, the team tested 250,000 mutant Rubiscos from cyanobacteria in E. coli bacteria engineered so their survival depends on the efficiency of the enzyme. "Finding answers on how to improve Rubisco is like looking for a needle in a haystack," Whitney said. "The beauty of this system is that it allows us to get rid of all those pieces of hay."

Eighteen Rubisco mutants survived the screen, eleven of which were found to be much more efficient at fixing carbon dioxide. They found these mutations are localized to a specific, previously unexplored region of cyanobacterial Rubisco. Now they hope to make similar tweaks to improve Rubisco in crops and increase their growth and yield.

Read the paper: An improved Escherichia coli screen for Rubisco identifies a protein-protein interface that can enhance CO2-fixation kinetics.

Article source: Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign.

Image credit: Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign

News

New study shows producers where and how to grow cellulosic biofuel crops

According to a recent ruling by the United States Environmental Protection Agency, 288 million gallons of cellulosic biofuel must be blended into the U.S. gasoline supply in 2018. Although this figure is down slightly from last year, the industry is still growing at a modest pace. However, until now, producers have had to rely on incomplete information and unrealistic, small-scale studies in guiding their decisions about which feedstocks to grow, and where. A new multi-institution report provides practical agronomic data for five cellulosic feedstocks, which could improve adoption and increase production across the country.


Europe's lost forests: Coverage has halved over 6,000 years

More than half of Europe's forests have disappeared over the past 6,000 years thanks to increasing demand for agricultural land and the use of wood as a source of fuel, new research led by the University of Plymouth suggests.


The circadian clock sets the pace of plant growth

The recent award of the Nobel Prize in Physiology or Medicine to the three American researchers Hall, Rosbash and Young for their "discoveries of molecular mechanisms controlling the circadian rhythm" has greatly popularized this term -which comes from the Latin words "circa" (around of) and "die" (day)-. Thanks to the discoveries that these scientists did using the fruit fly, today we know that the organisms have an internal clock built of a set of cellular proteins whose amount oscillates in periods of 24 hours. These oscillations, which are autonomously maintained, explain how living organisms adapt their biological rhythm so that it is synchronized with the Earth's revolutions.