Kartik Temburnikar, Ph.D.

Education: University of Maryland, Baltimore County, Ph.D. Organic Chemistry
Institution: Arizona State University, the Biodesign Institute (laboratory of John C. Chaput)

SCOL Project: Investigating TNA as a Candidate RNA Progenitor

The RNA world hypothesis postulates that cellular life based on DNA genomes
and protein enzymes was preceded in evolutionary history by RNA-based life forms that stored information and catalyzed chemical reactions. This hypothesis is supported by many lines of evidence, including the existence of RNA enzymes in nature.

Whether RNA was the first genetic material of life or an important evolutionary intermediate is not yet known. Problems associated with the prebiotic synthesis of ribose and non-enzymatic replication of RNA suggest that simpler genetic polymers whose structures were more accessible on the early Earth may have preceded RNA.

One possible candidate is threose nucleic acid, or TNA. TNA is a synthetic genetic polymer that contains a four-carbon threose sugar in place of nature’s five-carbon ribose sugar found in RNA. TNA is an attractive candidate for an RNA progenitor, because threose is chemically much simpler than ribose, and TNA can exchange genetic information with RNA. This latter observation provides a plausible mechanism for passing information between successive genetic systems. In addition to information storage and chemical simplicity, early genetic polymers would have also needed to fold into shapes with catalytic activity.

Kartik Temburnikar aims to explore the functional properties of TNA as an RNA progenitor by evolving a TNA enzyme capable of joining two strands of TNA together to form longer TNA polymers. If successful, this template-copying reaction will provide new insights into mechanisms that could have given rise to early self-replicating genetic polymers.