Newly discovered protein operated in earliest organisms

May 17, 2018, Universitaet Tübingen
Newly discovered protein operated in earliest organisms
Microscopic image of cells of the cyanobacterium Synechocystis sp. PCC6803Photo: Khaled Selim . Credit: Universitaet Tübingen

Life on Earth depends on photosynthetic carbon dioxide (CO2) fixation to form organic carbon. Plants take atmospheric CO2 and transform it into organic molecules such as glucose. This process evolved in cyanobacteria and was later conveyed to eukaryotes, giving rise to plastids in algae and plants. Researchers have now discovered a new protein which is involved in this complex process; it regulates the intake of CO2 into the cell. Khaled Selim and Professor Karl Forchhammer from the Interfaculty Institute for Microbiology and Infection Medicine (IMIT), together with colleagues from the Max-Planck Institute for Proteinevolution and from the University Rostock, describe their finding of the conserved cyclic AMP receptor protein, SbtB, in the latest edition of Proceedings of the National Academy of Sciences (PNAS).

SbtB participates in the sensing of fluctuating ambient CO2 concentrations to adjust CO2 fixation to different environments. SbtB represents a new member of the PII signal transduction superfamily, known for binding the energy carrier molecules ATP and ADP - a kind of battery for the cell. The newly discovered protein, however, also binds the cyclic nucleotide cAMP, which plays fundamental roles in all organisms for signalling the state of carbon metabolism. Up to now, cAMP was chiefly known for being a key messenger molecule, required in the maintenance of the organisms glucose balance - used for instance in regulating blood-sugar levels.

SbtB is the first protein known to bind cAMP to regulate the CO2 metabolism in cyanobacteria. In identifying SbtB, the researchers have found new principle of carbon sensing through cAMP, which is important for acclimation to varying Ci regimes in the ecological niches of . Cyanobacteria, also known as blue-green algae, are among the oldest group of organisms on Earth; knowing more about their workings offers clues to very early life on the planet.

Explore further: The origin of the chloroplast

More information: PII-like signaling protein SbtB links cAMP sensing with cyanobacterial inorganic carbon response. Proceedings of the National Academy of Sciences (PNAS), doi.org/10.1073/pnas.1803790115

Related Stories

The origin of the chloroplast

August 14, 2017

A new study, led by the University of Bristol, has shed new light on the origin, timing and habitat in which the chloroplast first evolved.

Recommended for you

Can China keep it's climate promises?

March 26, 2019

China can easily meet its Paris climate pledge to peak its greenhouse gas emissions by 2030, but sourcing 20 percent of its energy needs from renewables and nuclear power by that date may be considerably harder, researchers ...

What happened before the Big Bang?

March 26, 2019

A team of scientists has proposed a powerful new test for inflation, the theory that the universe dramatically expanded in size in a fleeting fraction of a second right after the Big Bang. Their goal is to give insight into ...

Cellular microRNA detection with miRacles

March 26, 2019

MicroRNAs (miRNAs) are short noncoding regulatory RNAs that can repress gene expression post-transcriptionally and are therefore increasingly used as biomarkers of disease. Detecting miRNAs can be arduous and expensive as ...

In the Tree of Life, youth has its advantages

March 26, 2019

It's a question that has captivated naturalists for centuries: Why have some groups of organisms enjoyed incredibly diversity—like fish, birds, insects—while others have contained only a few species—like humans.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.