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Scientists Identify “Pioneer Peptide” That May Have Sparked Life on Earth

Rutgers University scientists have identified a portion of a protein called “Nickelback” that is a likely candidate for kickstarting life on Earth over 3 billion years ago. This finding has important implications for the search for extraterrestrial life, as it offers a new clue for researchers to look for. The researchers believe that a few precursor proteins played a key role in the transformation from prebiotic chemistry to living biological systems, and “Nickelback” is one of these “pioneer peptides.”

Research could provide clues to extraterrestrial life.

A team of Rutgers University scientists dedicated to pinpointing the primordial origins of metabolism – a set of core chemical reactions that first powered life on Earth – has identified part of a protein that could provide scientists clues to detecting planets on the verge of producing life.

The research, published on March 10 in the journal Science Advances<em>Science Advances</em> is a peer-reviewed, open-access scientific journal that is published by the American Association for the Advancement of Science (AAAS). It was launched in 2015 and covers a wide range of topics in the natural sciences, including biology, chemistry, earth and environmental sciences, materials science, and physics.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>Science Advances, has important implications in the search for extraterrestrial life because it gives researchers a new clue to look for, said Vikas Nanda, a researcher at the Center for Advanced Biotechnology and Medicine (CABM) at Rutgers.

Based on laboratory studies, Rutgers scientists say one of the most likely chemical candidates that kickstarted life was a simple peptide with two nickel atoms they are calling “Nickelback” not because it has anything to do with the Canadian rock band, but because its backbone nitrogen atoms bond two critical nickel atoms. A peptide is a constituent of a protein made up of a few elemental building blocks known as amino acids<div class="cell text-container large-6 small-order-0 large-order-1">
<div class="text-wrapper"><br />Amino acids are a set of organic compounds used to build proteins. There are about 500 naturally occurring known amino acids, though only 20 appear in the genetic code. Proteins consist of one or more chains of amino acids called polypeptides. The sequence of the amino acid chain causes the polypeptide to fold into a shape that is biologically active. The amino acid sequences of proteins are encoded in the genes. Nine proteinogenic amino acids are called "essential" for humans because they cannot be produced from other compounds by the human body and so must be taken in as food.<br /></div>
</div>” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>amino acids

“Scientists believe that sometime between 3.5 and 3.8 billion years ago there was a tipping point, something that kickstarted the change from prebiotic chemistry – molecules before life – to­ living, biological systems,” Nanda said. “We believe the change was sparked by a few small precursor proteins that performed key steps in an ancient metabolic reaction. And we think we’ve found one of these ‘pioneer peptides’.”

A computer rendering of the Nickelback peptide shows the backbone nitrogen atoms (blue) that bond two critical nickel atoms (orange). Scientists who have identified this part of a protein believe it may provide clues to detecting planets on the verge of producing life. Credit: The Nanda Laboratory

The scientists conducting the study are part of a Rutgers-led team called Evolution of Nanomachines in Geospheres and Microbial Ancestors (ENIGMA), which is part of the Astrobiology program at NASAEstablished in 1958, the National Aeronautics and Space Administration (NASA) is an independent agency of the United States Federal Government that succeeded the National Advisory Committee for Aeronautics (NACA). It is responsible for the civilian space program, as well as aeronautics and aerospace research. Its vision is "To discover and expand knowledge for the benefit of humanity." Its core values are "safety, integrity, teamwork, excellence, and inclusion." NASA conducts research, develops technology and launches missions to explore and study Earth, the solar system, and the universe beyond. It also works to advance the state of knowledge in a wide range of scientific fields, including Earth and space science, planetary science, astrophysics, and heliophysics, and it collaborates with private companies and international partners to achieve its goals.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>NASA. The researchers are seeking to understand how proteins evolved to become the predominant catalyst of life on Earth.

When scouring the universe with telescopes and probes for signs of past, present or emerging life, NASA scientists look for specific “biosignatures” known to be harbingers of life. Peptides like nickelback could become the latest biosignature employed by NASA to detect planets on the verge of producing life, Nanda said.

An original instigating chemical, the researchers reasoned, would need to be simple enough to be able to assemble spontaneously in a prebiotic soup. But it would have to be sufficiently chemically active to possess the potential to take energy from the environment to drive a biochemical process.

To do so, the researchers adopted a “reductionist” approach: They started by examining existing contemporary proteins known to be associated with metabolic processes. Knowing the proteins were too complex to have emerged early on, they pared them down to their basic structure.

After sequences of experiments, researchers concluded the best candidate was Nickelback. The peptide is made of 13 amino acids and binds two nickel ions.

Nickel, they reasoned, was an abundant metal in early oceans. When bound to the peptide, the nickel atoms become potent catalysts, attracting additional protons and electrons and producing hydrogen gas. Hydrogen, the researchers reasoned, was also more abundant on early Earth and would have been a critical source of energy to power metabolism.

“This is important because, while there are many theories about the origins of life, there are very few actual laboratory tests of these ideas,” Nanda said. “This work shows that, not only are simple protein metabolic enzymes possible, but that they are very stable and very active – making them a plausible starting point for life.”

Reference: “Design of a minimal di-nickel hydrogenase peptide” by Jennifer Timm, Douglas H. Pike, Joshua A. Mancini, Alexei M. Tyryshkin, Saroj Poudel, Jan A. Siess, Paul M. Molinaro, James J. McCann, Kate M. Waldie, Ronald L. Koder, Paul G. Falkowski and Vikas Nanda, 10 March 2023, Science Advances.
DOI: 10.1126/sciadv.abq1990

Other Rutgers researchers on the study include: Distinguished Professor Paul Falkowski and Jennifer Timm, a postdoctoral associate, in the Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences at the School of Environmental and Biological Sciences; Joshua Mancini, Douglas Pike, Saroj Poudel and Alexei Tyryshkin, postdoctoral associates, and doctoral student Jan Siess at the Center for Advanced Biotechnology and Medicine and in the Department of Biochemistry and Molecular Biology at Robert Wood Johnson Medical School; and Kate Waldie, an assistant professor of the Department of Chemistry and Chemical Biology at the School of Arts and Sciences.

Researchers from the City College of New York also participated in the study.

Source: SciTechDaily