With a nefarious history, arsenic is synonymous with poison. As such it functions by blocking conversion of pyruvate to acetyl coenzyme A (CoA), thus the citric acid cycle activity is decreased, and production of ATP is decreased.
Consequently, when the salt-loving bacteria, strain GFAJ-1 growing in briny Mono Lake near Yosemite, was reported to have incorporated Arsenate into it’s DNA replacing phosphate, some high brow eyes were raised. A natural event, the lake has no outlet, so over millennia has become one of the highest natural concentrations of arsenic on Earth.
Origin of life investigators used this observation to remind us why it’s important to think outside the box. “Life as we know it requires particular chemical elements and excludes others,” said Ariel Anbar, a biogeochemist and astrobiologist from Arizona State University. “But are those the only options? How different could life be on other planets?
Sources cited: Wikipedia;