The first life on the early Earth arose around 4.29 billion years ago from the ocean, a salty environment that hurt the cell structures. Debates on how early life emerged and survived in such condition continues but, recently, a team of researchers from the Keller Research Group at the UW came up with one explanation.
The study, published in the Proceeding of the National Academy of Sciences on Aug. 12, suggests that besides building proteins, amino acids help to stabilize the cell structure when there is a high concentration of salt in the environment. They bind to the fatty acid membrane which are vulnerable to salt and prevents the membrane from being destructed.
In 2013, the team discovered that components of RNA may attach to and protect the fatty acid membranes. After that, they hypothesized amino acids — a building component of DNA — might have the same effects.
“It is serendipitous that we found these components stick to the membranes,” Caitlin Cornell, a UW doctoral student in the department of chemistry and the lead author of the paper said. “[We think] amino acids convey a protective effect on the membrane, and in experiments they really did.”
According to Cornell and the other author Roy Black, affiliate professor of bioengineering at the UW, amino acids not only protect membranes from salt but also from ions that present in the ocean –– for example, magnesium ions.
The assumption that life starts from simple membranes receives lots of skepticism because of the harm salt and magnesium ions cause. The new finding makes this scenario more feasible. It provided a possible explanation for how complex organized cell develops from individual components.
According to Black, this process makes the membranes more stable.
“It reinforces the idea that the membranes could have been the apex point to bring together building blocks for all other important molecules,” Cornell said.
Cornell also has a further interest in testing different ways in which membranes can be stabilized against salt and other disturbing molecules.
As Black mentioned, the following question of this discovery is to demonstrate the components that stick to membranes actually form RNA and proteins. The team imitates the environment on the early Earth and observes the response of these components.
“This is a really huge issue in the whole field [of studying origins of life],” Black said. “Polymers are long-chained building components in RNA. How do they form in the early life?
The study also suggested that life could arise elsewhere in the universe because cell formation might solely depend on molecular interactions and simple chemistry. As long as there are favorable conditions, life can emerge somewhere else besides the earth.
“It really captures public imagination on the origins of life,” Cornell said. “It is utilizing scientific techniques to start to answer fundamental basic questions: Where do we come from? Where do cells come from? How do they arrive? I think that is really powerful about this research.”
Reach reporter Sunny Wang at firstname.lastname@example.org. Twitter: @sunnyqwang64
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