Boron compound stops fungal enzyme

A newly identified antifungal agent works in an unusual way by inhibiting one of the aminoacyl-transfer RNA synthetases (AARSs), enzymes that catalyze the attachment of amino acids to their corresponding tRNA during protein translation. AN2690 (shown) is a member of the boron-containing class of compounds called benzoxaboroles. Scientists at Anacor Pharmaceuticals, Palo Alto, Calif., and collaborators show that AN2690 forms an adduct with tRNA in the leucyl-tRNA synthetase's editing site (Science 2007, 316, 1759). They find that the boron atom is key to the inhibition, both in terms of its identity and its location in the molecule. Experiments with a series of analogs revealed that changing boron to boronic acid or replacing it with carbon stops the inhibitor from working. Leucyl-tRNA synthetase is an example of an AARS with separate synthetic and proofreading active sites. The authors suggest that other oxaboroles could be used to inhibit similar AARSs.