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posted by martyb on Saturday December 02 2017, @02:03AM   Printer-friendly
from the waiting-for-an-off-base-pear dept.

In 2014, scientists engineered Escherichia coli to incorporate new bases they called 'X' and 'Y' in addition to adenine-thymine (A-T) and guanine-cytosine (G-C). Now it has been demonstrated that these synthetic base pairs can be transcribed into RNA and used to produce a protein containing "unnatural" amino acids.

The addition of the new bases could increase the amount of amino acids from 20 to a possible total of 172.

A semi-synthetic organism that stores and retrieves increased genetic information (DOI: 10.1038/nature24659) (DX)

Since at least the last common ancestor of all life on Earth, genetic information has been stored in a four-letter alphabet that is propagated and retrieved by the formation of two base pairs. The central goal of synthetic biology is to create new life forms and functions, and the most general route to this goal is the creation of semi-synthetic organisms whose DNA harbours two additional letters that form a third, unnatural base pair. Previous efforts to generate such semi-synthetic organisms culminated in the creation of a strain of Escherichia coli that, by virtue of a nucleoside triphosphate transporter from Phaeodactylum tricornutum, imports the requisite unnatural triphosphates from its medium and then uses them to replicate a plasmid containing the unnatural base pair dNaM–dTPT3. Although the semi-synthetic organism stores increased information when compared to natural organisms, retrieval of the information requires in vivo transcription of the unnatural base pair into mRNA and tRNA, aminoacylation of the tRNA with a non-canonical amino acid, and efficient participation of the unnatural base pair in decoding at the ribosome. Here we report the in vivo transcription of DNA containing dNaM and dTPT3 into mRNAs with two different unnatural codons and tRNAs with cognate unnatural anticodons, and their efficient decoding at the ribosome to direct the site-specific incorporation of natural or non-canonical amino acids into superfolder green fluorescent protein. The results demonstrate that interactions other than hydrogen bonding can contribute to every step of information storage and retrieval. The resulting semi-synthetic organism both encodes and retrieves increased information and should serve as a platform for the creation of new life forms and functions.

Previously: Scientists Engineer First Semisynthetic Organism With Three-base-pair DNA

Related: How Scientists Are Altering DNA to Genetically Engineer New Forms of Life


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  • (Score: 2) by takyon on Sunday December 03 2017, @10:22AM

    by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Sunday December 03 2017, @10:22AM (#604609) Journal

    The focus going forward should be on bolstering human defenses against biological agents rather than trying to regulate amateur biology and suppress citizen science, which will only turn ugly fast.

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