Researchers at the University of Utah have debunked the idea that DNA and messenger RNA (mRNA) are required in order to produce amino acids. There findings are based on the discovery of a new protein, Rqc2, which effectively plays the part of mRNA and determines which amino acids need be put together in a cellular mechanism in order to build a new protein.
The finding was based on the researchers using “cryo-electron microscopy” in order to take a quick “picture” of active cells in order to observe the work of ribosomes. The researchers compared cell life to an assembly line where amino acids are put together in a specific order. Ribosomes effectively add these proteins in a specific order, but if something goes wrong the ribosome is disassembled and its partial creation is recycled.
Proteins without DNA instructions: Quality control
Peter Shen, the study’s first author, along with his colleagues found that before recycling is complete, Rqc2 can call on ribosomes to add additional amino acids in any order. There are 20 amino acids that make up human life as we know it. The researchers believe that Rqc2 is essentially working in a quality control capacity and that this illogical order of amino acid “manufacturing” could be a test to determine if a ribosome is working correctly.
Shen called the findings “surprising” adding that “the discovery reflects how incomplete our understanding of biology is.”
“Nature is capable of doing a lot more than what has been earlier thought,” Shen said.
“Our work uncovers an unexpected mechanism of protein synthesis, in which a protein — not an mRNA — determines tRNA recruitment and the tagging of nascent chains with carboxy-terminal Ala and Thr extensions,” the researchers wrote in Science.
Looking to the future
“Our job now is to determine when and where this process happens, and what happens when it fails,” said Dr. Adam Frost, assistant professor at University of California, San Francisco (UCSF). The study, in addition to involving researchers from the University of Utah and UCSF, also included researchers from the University of Texas in Austin.
These new findings could, in theory, play a large part in next-generation treatments for neurodegenerative diseases such as Amyotrophic lateral sclerosis (ALS), Huntington’s and Alzheimer’s disease.
Of that group, Alzheimer’s is certainly the most prevalent with and estimated 5 million Americans living with the disease that kills around 500,000 each year.
