In two studies, published in the journal Cell, the team which included an academic from the University of York’s Department of Biology, reported the first detailed inventory of the cellular machinery — located in an organelle known as the pyrenoid — that algae use to collect and concentrate carbon dioxide.
Furthermore, they found that the pyrenoid, long thought to be a solid structure, actually behaves like a liquid droplet that can dissolve into the surrounding cellular medium when the algal cells divide.
“We believe the liquid-like nature of the pyrenoid allows it to rapidly change from a condensed state to a dissolved state in response to a changing environment, further explaining why pyrenoid containing algae have become so efficient at photosynthesis”, said Dr Luke Mackinder, the lead author of one of the papers and a former postdoctoral researcher at the Carnegie Institution who now leads a team of researchers at the University of York.
Aquatic algae and a handful of other plants have developed carbon-concentrating mechanisms that boost the rate of photosynthesis, the process by which plants turn carbon dioxide and sunlight into sugars for growth. All plants use an enzyme called Rubisco to “fix” carbon dioxide into sugar that can be used or stored by the plant.
Algae have an advantage over many land plants because they cluster the Rubisco enzymes inside the pyrenoid, where the enzymes encounter high concentrations of carbon dioxide pumped in from the air. Having more carbon dioxide around allows the Rubisco enzymes to work faster.
The research revealed 89 new pyrenoid proteins, including ones that the researchers think usher carbon into the pyrenoid and others that are required for formation of the pyrenoid.
They also identified three previously unknown layers of the pyrenoid that surround the organelle like the layers of an onion.
“The information represents the best assessment yet of how this essential carbon-concentrating machinery is organized and suggests new avenues for exploring how it works,” said Dr Mackinder.
Source : University of York