West LA Times

A recent study published in Nature Communications by researchers from UCLA and NASA's Goddard Space Flight Center provides new insights into the origin of life. The research suggests that RNA, a fundamental molecule in the early stages of life, did not initially show a chemical bias for one chiral form of amino acids. This finding challenges previous assumptions about molecular homochirality, which refers to the preference for molecules to exist in one "handedness" or chirality.

Chirality is a property where molecules can have mirror-image forms, similar to left and right hands. In biological systems on Earth, all sugars are "right-handed," and amino acids are "left-handed." However, the study reveals that this preference may not have been predetermined in early life's development.

The researchers conducted experiments using ribozymes—small RNA molecules known to catalyze chemical reactions—to simulate conditions on early Earth during what is known as the "RNA world." They aimed to determine whether right-handed ribozymes consistently produced left-handed amino acids or if variations occurred. Testing 15 different ribozymes revealed that these could favor either handedness of amino acids.

Study leader Irene Chen from UCLA stated, "Earlier work in this area was inspired more by chemical structures in our existing biology, whereas our study looked at any RNAs that would react with the activated amino acid at any position along the strand."

The findings suggest that life's eventual homochirality might not result from chemical determinism but rather emerged through evolutionary pressures. Study author Alberto Vázquez-Salazar emphasized the adaptability of RNA as a model for studying early evolution and biological homochirality.

Jason Dworkin from NASA's Goddard Space Flight Center highlighted how understanding life's chemical properties aids in searching for extraterrestrial life. Dworkin mentioned ongoing analyses of samples from asteroids like Bennu and future Mars missions to test for signs of life including ribozymes and proteins.

The research received support from NASA, the Simons Foundation Collaboration on the Origin of Life, and the National Science Foundation. Co-authors include Josh Kenchel, Evan Janzen, Reno Wells, Krishna Brunton (UC Santa Barbara), Kyle Schultz (UCLA), Ziwei Liu (University of Cambridge), Weiwei Li (UC Santa Barbara), and Eric Parker (NASA Goddard).

Chen also holds a faculty position at UCLA's Chemistry & Biochemistry Department.