Chemical Evolution of a Bacterium’s Genome

Abstract

Automated selection was used to evolve an Escherichia coli strain unable to synthesize thymine nucleotides into a chemically modified organism whose DNA genome is composed of adenine, cytosine, guanine, and an artificial base, the thymine analogue 5‐chlorouracil. Evolving cells were initially observed as irregular filaments and progressively recovered the appearance of short rods typical of wild‐type E. coli (see picture).

Organic fluorine as a polypeptide building element: in vivo expression of fluorinated peptides, proteins and proteomes

“…Only very recently, Marlière and co-workers succeeded in the incorporation of 5-chlorouracil instead of thymine into a genome. 169 The E. coli strain whose progeny retained the ability to use 5-chlorouracil is the first in vivo proof of a canonical-non-canonical border crossing in the field of nucleic acid research. This success in halogenation of a genome implies the question whether halogenation, i.e.…”

Secret life

“…Already, there are various projects underway to create life from scratch here on Earth-part of the burgeoning field of synthetic biology (11). In the last several years, biologists have attempted to create exotic life-forms, using, for example, new nucleotides (12).…”

The effect of chlorination of nucleotide bases on the conformational properties of thymidine monophosphate

“…I n a recent paper [1] it was reported that an international group of scientists working in xenobiology, a new brunch of life sciences, has succeeded in creating escherichia coli bacteria, in which DNA thymine was substituted with 5-chlorouracil of synthetic origin -a substance which is toxic to other organisms. Having successfully replaced the natural nucleotide base, the scientists began to test the vital functions of the modified organisms.…”