New evidence suggests a human protein can build and edit other proteins. It's the first time the process has been observed by scientists.
If the human system were a bee colony, proteins would be the worker bees -- industrious and versatile, capable of producing the body's vital materials. And if proteins are the worker bees, then DNA is the queen, offering the instructions for where to go and what to build.
The work orders are delivered via messenger RNA (mRNA) to amino acids inside human cells called ribosomes. The ribosomes spawn the specialized proteins that then venture out into the human body to do their job -- fight disease, rebuild muscle, trigger hormone production.
Previously, it was assumed only DNA and mRNA could specify the ingredients (amino acids) that form a new protein. But a new study has shown that one unique protein can deliver instructions to form and augment a new protein on its own, without the assistance of messenger RNA.
"This surprising discovery reflects how incomplete our understanding of biology is," study author Peter Shen, a biochemistry researcher at the University of Utah, said in a recent press release. "Nature is capable of more than we realize."
The protein-building protein, called Rqc2, doesn't flex its muscles willy-nilly. Its unique abilities are only called into action when there is a mistake in the protein-building assembly line. Occasionally, the ribosome malfunctions and can't process the protein-building instructions delivered by the mRNA. In these instances, Rqc2 steps in and delivers filler instructions, ordering the ribosome to slap on a random sequence of two amino acids (alanine and threonine) -- a stopgap measure until the proper instructions are resumed.
"In this case, we have a protein playing a role similar to that filled by mRNA," explained study co-author Adam Frost, M.D., a biochemistry professor at both the University of California, San Francisco and the University of Utah.
Researchers say the unique process is like a quality control mechanism, the uniform insert a possible signal that the faulty protein needs to be destroyed. Because a range of disorders, including Alzheimer's and Huntington's, are believed to -- at least in part -- derive from problems with the body's protein-construction processes, better understanding Rqc2 could eventually lead to improved treatments for such diseases.
The new study was published this week in the journal Science.