Readers may recall the media hype, back in December 2010, surrounding the claim that a bacterium is capable of utilising arsenic instead of phosphorous in its DNA. A new study, published in Nature and reported on by Nature News, has discovered that the bacterium “actually goes to extreme lengths to grab any traces of phosphorus it can find.”
The Nature News press release goes on to report,
The finding clears up a lingering question sparked by a controversial study, published in Science in 2010, which claimed that the GFAJ-1 microbe could thrive in the high-arsenic conditions of Mono Lake in California without metabolizing phosphorus — an element that is essential for all forms of life.
Dan Tawfik, who studies protein function at the Weizmann Institute of Science in Rehovot, Israel, and his colleagues have now teased out the mechanism by which some of the bacterial proteins bind to phosphate and not arsenate. The study, published today in Nature, suggests that just one chemical bond holds the key, and shows that the ‘arsenic-life’ bacteria have a strong preference for phosphorus over arsenic.
The exceedingly high preference for phosphorus found in the key proteins in that species represent “just the last nail in the coffin” of the hypothesis that GFAJ-1 uses arsenic in its DNA, says Tawfik.
The latest paper shows that the “arsenic monster” GFAJ-1 goes to a huge amount of effort, “even more than other life”, to avoid arsenate, says Wolfgang Nitschke from the Mediterranean Institute of Microbiology in Marseilles, France, who co-authored a commentary questioning the conclusion that GFAJ-1 could replace phosphate with arsenate. “This shows clearly that life doesn’t like arsenate in cytoplasm,” he says.