Nature:
A recent paper refutes once and for all the controversial
findings of a
2010
study published in
Science concerning a bacterium that can supposedly
survive by substituting arsenic, which is toxic, for
phosphorus, which is generally considered to be indispensable.
Felisa Wolfe-Simon, lead author of the original paper, had
claimed that the GFAJ-1 microbe thrives in the high-arsenic
conditions of Mono Lake, California, because it can metabolize
the usually poisonous substance. Although that claim was
challenged by many in the field, no one knew how the bacterial
proteins could discriminate between molecules of phosphate and
arsenate, which are nearly identical. Now Dan Tawfik (Weizmann
Institute of Science, Rehovot, Israel) and colleagues, whose
paper
was published yesterday in
Nature, have found that it all depends on a single
bond between a hydrogen atom and the protein. That does not
mean that arsenate does not get into the bacteria. Said Tawfik,
"It just shows that this bacterium has evolved to extract
phosphate under almost all circumstances."
