Threose nucleic acid

Threose nucleic acid (TNA) is an artificial genetic polymer invented by Albert Eschenmoser. TNA has a backbone structure composed of repeating threose sugars linked together by phosphodiester bonds. Like DNA and RNA, TNA can store genetic information in strings of nucleotide sequences (G, A, C, and T). TNA is not known to occur naturally and is synthesized chemically in the laboratory under controlled conditions.

TNA can self-assemble by Watson-Crick pair bonding into duplex structures that closely approximate the helical geometry of A-form RNA. TNA can also base pair opposite complementary strands of DNA and RNA, which makes it possible to share information with natural genetic polymers. This capability and chemical simplicity suggests that TNA could have preceded RNA as a genetic material.

Polymerases have been identified that can replicate TNA polymers in the laboratory. TNA replication occurs through a process that mimics RNA replication. In these systems, TNA is reverse transcribed into DNA, the DNA is amplified by PCR, and then forward transcribed back into TNA.

TNA replication coupled with in vitro selection has produced a TNA aptamer that binds to human thrombin. This example demonstrates that TNA is capable of heredity and evolution, which is a hallmark of life.

TNA has generated great interest in Synthetic Biology because TNA polymers are resistant to nuclease degradation. This property, coupled with its ability to undergo Darwinian evolution in a test-tube, provide a possible path to biologically stable molecules with relevance in material science and molecular medicine.

See also

• Oligonucleotide synthesis
• Abiogenesis
• Glycol nucleic acid
• Peptide nucleic acid

External links

• Was simple TNA the first nucleic acid on Earth to carry a genetic code?, New Scientist
• ORIGIN OF LIFE: A Simpler Nucleic Acid, Leslie Orgel

References

• Orgel, Leslie (November 2000). "A Simpler Nucleic Acid". Science 290 (5495): 1306–1307. doi:10.1126/science.290.5495.1306. PMID 11185405. 

• Watt, Gregory (February 2005). "Modified nucleic acids on display". Nature Chemical Biology. doi:10.1038/nchembio005. 

• Schoning, K; Scholz P; Guntha S; Wu X; Krishnamurthy R; Eschenmoser A (November 2000). "Chemical etiology of nucleic acid structure: the alpha-threofuranosyl-(3'->2') oligonucleotide system.". Science 290 (5495): 1347–51. doi:10.1126/science.290.5495.1347. PMID 11082060.