U.S. Department of Energy

Pacific Northwest National Laboratory

With the Circadian Clock, Proteins Can Have Their Own Rhythm

By studying how proteins are regulated by circadian rhythms, scientists are discovering that RNA doesn’t play as large a role as previously thought, opening the door for advances in the medical, biofuels, and bioproducts.

Most in-depth proteome study of its kind shows mRNA is not essential for metabolic proteins to follow a 24-hour rhythm

A plethora of organisms rely on the 24-hour light/dark rhythm of the circadian clock to anticipate changes in their external environment and give appropriate responses, like going to sleep when its dark and rising when its light.  Such responses are facilitated by the production of specific proteins through rhythmic processes that rely on regular changes in the amount of messenger RNA (mRNA) present in a cell.  The mRNA itself follows a daily schedule.

Even so, when it comes to the idea that protein synthesis is ruled by the levels of mRNA present at any given time, a recent study published in Cell Systems last December defied expectations by demonstrating that the circadian clock plays an independent and substantial role in protein production.

Working with colleagues at the Environmental Molecular Sciences Laboratory and joined by scientists from the Rensselaer Polytechnic Institute and the Geisel School of Medicine at Dartmouth, researchers from PNNL found that the production levels of many proteins in fungal cells changed despite a fixed level of matching mRNA being present.  The team of scientists used a circadian clock akin to that which humans rely on to affect protein levels in fungal cells, verifying the clock as an independent, important regulator of an organism’s metabolic output.

So, even though mRNA plays a key role in protein production, a significant portion of synthesis is regulated by the clock regardless of how much mRNA is present.

The timing of protein production is directly related to the interplay and functionality of various metabolic pathways essential for a cell’s operation.  Having a better understanding of the circadian clock’s role in cellular and organismal functions has implications for advances in the biofuels, bioproducts, and medical fields.

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March 2019
| Pacific Northwest National Laboratory