Green algae reveal one mRNA encodes many proteins

February 22, 2021

In eukaryotes, gene expression was long held to be "monocistronic," which means that a single gene makes messenger RNA that then encodes a single protein. In a new study published the Proceedings of the National Academy of Sciences (PNAS),  a team of researchers in professor Sabeeha Merchant's lab in the Department of Plant and Microbial Biology has now discovered numerous exceptions. Their research has uncovered that, among two species of green algae (Chlamydomonas reinhardtii  and Chromochloris zofingiensis),  two or more genes are encoded on a single molecule of mRNA.

“I was scrutinizing the genes of one of our species of algae and kept seeing what looked like mistakes by the gene prediction algorithms," recalls Sean Gallaher, a research scientist in Merchant’s lab and first author of the article. "I decided to dig in a little deeper, and realized what was really happening.” 

"Our discovery reveals an unknown similarity between bacteria and more complex forms of life," says Merchant in a short video about the discovery (below). The findings have implications for the creation of new synthetic biology tools, with potential applications for biofuel development and other advancements.

The Merchant lab studies the dynamics of essential trace-metals—copper, zinc, iron, manganese—in metabolism and homeostasis in green alga, using classical genetics, transcriptomics and proteomics, elemental analysis, and high-resolution metal imaging. The researchers also employ comparative genomics to better understand green algal lineages. 

The research team included scientists from UC Berkeley, UCLA, UC Davis, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory, the U.S. Department of Energy (DOE) Joint Genome Institute (JGI), a DOE Office of Science User Facility located at Berkeley Lab, and the Environmental Molecular Sciences Laboratory (EMSL), a DOE Office of Science user facility. 

This article was adapted from a press release on the Joint Genome Institute website. The original study can be found on the PNAS website.