Old mutation key to multicellular life

An ancient mutation that occurred a billion years ago may have set the stage for multicellular life according to new research.

Using advanced computational methods, a protein essential for multicellular cells known as GK-PID was traced back in time, revealing its evolutionary origins.

The research, lead by co-author Joe Thornton, PhD, professor of human genetics and ecology and evolution at the University of Chicago, demonstrated that around one billion years ago a mutation in a gene known as gk led to it doubling up. This subsequently led to a change in its function and so the creation of a new protein known as GK-PID. 

GK-PID, which is short for Guanylate Kinase protein interaction domain, plays an essential role in the division of multicellular cells, orienting the daughter’s cells correctly. It acts as molecular carabiner, joining an anchoring protein to a motor protein, which together orients the daughter cells correctly.

“Our experiments show that the GK-PID evolved its carabiner function early, before multicellularity itself appeared,” Thornton said. “That one ancient mutation yielded a wholly new molecular function, which helped set the stage for multicellular animals to eventually evolve.”

“Before the last common ancestor of all animals, when only single-celled organisms existed on Earth, just one tiny change in DNA sequence caused a protein to switch from its primordial role as an enzyme to a new function that became essential to organize multicellular structures” said Thornton.

The researchers hope that the technique they used may also be used for understanding the evolution of other proteins involved in key cellular processes. As while it is known that multicellular life is dependent on a range of cellular process, very little is known about how or where these processes evolved.