MICROBIOLOGY: Every Silver Lining Has a Cloud

Molecular Microbiology 38, 658 (2000)

Caroline Ash

Many disease-causing filamentous fungi of plants and animals produce toxins, notorious among these is aflatoxin, which can cause liver cancer in people and livestock who have eaten affected nuts and seeds. This intractable agricultural problem urgently requires control. While investigating how aflatoxin production is regulated, Tag et al. discovered that a cellular signaling protein FadA, a heterotrimeric G protein, inhibited the production of aflatoxin and other carcinogens in these fungi, as well as suppressing spore formation. Nevertheless, although aflatoxin production was suppressed, penicillin production was stimulated.  In some instances this kind of response might be valuable, but stimulating antibiotic release into the environment may cause other problems.  Furthermore, increased antibiotic production was accompanied by a general shift in the production of other metabolites, including other potent toxins. Thus any strategy that targets G-proteins in pathogens in order to control one toxin could lead to the accidental production of an alternative poison. -- CA