Absence of arsenate in DNA from arsenate-grown GFAJ-1 cells

TL;DR

This study demonstrates that GFAJ-1 bacteria do not incorporate arsenate into their DNA, challenging previous claims that arsenate replaces phosphorus in DNA structure under phosphate-limited conditions.

Contribution

The paper provides evidence that arsenate is not incorporated into DNA of GFAJ-1, refuting earlier reports of arsenate substitution in DNA in arsenate-grown cells.

Findings

Arsenate does not support GFAJ-1 growth under phosphate limitation.

DNA from arsenate-grown cells shows no covalent arsenate incorporation.

Mass spectrometry detects only trace arsenate in DNA.

Abstract

A strain of Halomonas bacteria, GFAJ-1, has been reported to be able to use arsenate as a nutrient when phosphate is limiting, and to specifically incorporate arsenic into its DNA in place of phosphorus. However, we have found that arsenate does not contribute to growth of GFAJ-1 when phosphate is limiting and that DNA purified from cells grown with limiting phosphate and abundant arsenate does not exhibit the spontaneous hydrolysis expected of arsenate ester bonds. Furthermore, mass spectrometry showed that this DNA contains only trace amounts of free arsenate and no detectable covalently bound arsenate.