Osaka University-led Japanese researchers identify huge motor complex that imports proteins into chloroplasts
Over 1 billion years ago, a relationship began between the ancestor of all living plants and a type of bacterium that paved the way for the evolution of life as we know it.
The single-celled algal ancestor engulfed, but crucially did not destroy, a cyanobacterium-like organism with which it established a mutually beneficial bond. This symbiotic relationship provided energy in the form of sugars derived from photosynthesis (whereby sunlight is converted into chemical energy) from the cyanobacterium to its host.
The symbiont cell eventually became the first chloroplast. Even today, these organelles hold on to structures from their early days as independent organisms, including their own DNA and a double membrane. During evolution, several chloroplast-encoded genes transferred to the host's nuclear genome. Thus, in modern plant and algal cells, many nuclear-encoded chloroplast proteins synthesized in the cytosol of the cell must be imported across both the outer and inner chloroplast membranes in a process that requires energy.
In 2013, Osaka University researchers headed by Masato Nakai discovered and characterized a huge novel transport channel (TIC) in the inner chloroplast membrane through which proteins were transported (Science, 339, 571--574.) However, the motor that enables proteins to be imported across the inner membrane remained a mystery.
Now, in The Plant Cell, this same team has collaborated with other Japanese researchers to report the identification of the elusive protein transport motor that is essential for chloroplast formation.
"We identified another huge novel protein complex, twice the mass of TIC, which is made up of six related proteins with one accessory protein, and functions as the import motor in a close association with TIC," says Nakai. "Surprisingly, the six related components all evolved from an enzyme contained within the ancestral cyanobacterium-like endosymbiont that degraded unwanted proteins after extracting them from the membrane."
Although the protein breakdown role has since been lost during evolution, the extraction function has been retained to be utilized as an import motor. The team believes that simultaneous increases in the size of components of TIC and the newly identified motor occurred early in the evolution of the green algae, perhaps to improve protein import efficiency.
"These findings revolutionize the molecular model of chloroplast protein import, and help us understand the evolution of plant and algal chloroplasts," explains Nakai. "This understanding could aid biotechnological improvements in the efficiency of crop photosynthesis, or the development of plants and algae as factories that manufacture or store proteins in their chloroplasts."
This article, "A Ycf2-FtsHi heteromeric AAA-ATPase complex is required for chloroplast protein import" was published in The Plant Cell at DOI: https:/
A 2013 article related to this research was published in Science at DOI: https:/
About Osaka University
Osaka University was founded in 1931 as one of the seven imperial universities of Japan and now has expanded to one of Japan's leading comprehensive universities. The University has now embarked on open research revolution from a position as Japan's most innovative university and among the most innovative institutions in the world according to Reuters 2015 Top 100 Innovative Universities and the Nature Index Innovation 2017. The university's ability to innovate from the stage of fundamental research through the creation of useful technology with economic impact stems from its broad disciplinary spectrum.
Saori Obayashi | EurekAlert!
Microscope measures muscle weakness
16.11.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg
Good preparation is half the digestion
16.11.2018 | Max-Planck-Institut für Stoffwechselforschung
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
16.11.2018 | Health and Medicine
16.11.2018 | Life Sciences
16.11.2018 | Life Sciences