Rutgers researchers discover key protein structures that may be responsible for origins of life

A recent Rutgers study has provided insight into the protein structures that may be responsible for the origins of life from the “primordial soup” — a mixture of organic compounds present in Earth’s ancient oceans.

Yana Bromberg, a professor in the Department of Biochemistry and Microbiology and lead author of the study, said that it is difficult to discern how life arose on Earth because it has been more than four billion years since life first appeared.

She said no fossils remain from that period of time and drastic changes in the planet’s environments have wiped any possible biological record of the origin of life.

Though, the study’s researchers believe they have identified important protein building blocks that could have evolved over time to form the enzymes necessary to create life. She said these findings are significant because they could reveal more information about the planet’s beginnings.

“Our findings are historically ... important and could inform the evolutionary patterns in early Earth history,” Bromberg said. “They also may be useful for synthetic protein design and for evaluating the likelihood of (the) appearance of life on other planets and planetary bodies.”

She said the team of researchers considered how all living organisms can perform electron transfer, a chemical process in which electrons are moved from one atom to another, and assumed that this ability was present in early life, as well.

Taking this knowledge into consideration, the researchers decided to study metal-binding proteins that could combine the functions of both metals and proteins, according to a press release.

Bromberg said they compared present-day metal-binding proteins to look for structural commonalities between them, which could demonstrate whether any shared features could have been present in ancient proteins and evolved to create the structures that exist today. 

“We looked for structural similarities of proteins and reinforced this knowledge with sequence similarities,” she said. “Structural similarity suggests similar function (which may have evolved independently), but sequence overlap also informs possible evolutionary relationships.”

The team of researchers used a computational method to understand possible evolutionary links between metal-binding proteins and discovered that most of the proteins have similar features regardless of their function or originating organism, according to the study.

The team found that these proteins were likely used to conduct electron transfer during early life on Earth and have since been reused for various biological activities.

Additionally, they discovered that the first biologically functional protein structures preceded fully functional protein folds, three-dimensional structures made of protein chains, according to the study.

Bromberg said that the technical methods of sequence and structure comparison that were used in the study have been around for approximately 20 years. The conceptual aspects, which include the work of Russian biochemist Aleksandr Oparin, have existed for the past century.

In the future, she said the team would like to look into factors that caused this protein diversification, or transformation, as well as the specific arrangements of the protein building blocks that evolved to create today’s structures.

“Our work is only one of the first pieces of the puzzle,” Bromberg said. “There are plenty of questions that can and should be asked on top of our findings and methods: How were the building blocks arranged to give us the current variety? What spurred further diversification? Was it random? What is considered true ‘life,’ and when did that arise?”

Bromberg said the study’s findings contribute to the field of synthetic biology as well as humanity’s search for life on other planetary bodies. 

“The assumption is that the same rules that apply to our world also apply on other planets and in the lab,” she said. “Thus, knowing what happened here could help understand everywhere else.”