Coral Genome Leads to Alternative Amino Acid Pathway Found in Other Non-Model Animals

A research team from Saudi Arabia and Australia describes an alternative cysteine amino acid biosynthesis pathway present in the Acropora loripes coral genome for a paper appearing in Science Advances. Contrary to past studies suggesting that the coral turns to symbiosis with Symbiodiniaceae family dinoflagellates to make up for the loss of a cystathionine beta-synthase (CBS) gene that codes for an enzyme involved in the traditional cysteine biosynthesis pathway, the investigators uncovered another cysteine biosynthesis pathway that relies on homologs of the Cys2 succinyltransferase and Cys1a sulfhydrylase enzymes previously linked to an alternative cysteine pathway in fungi. "We demonstrate that these coral proteins are functional and synthesize cysteine in vivo, exhibiting previously unrecognized metabolic capabilities in animals," the authors report, noting that the same pathway "is also present in most animals, but absent in mammals, arthropods, and nematodes, precisely the groups where most of the animal model organisms belong to, highlighting the risks of generalizing findings from model organisms."