Shigella bacteria constitute the causative agent of bacillary dysentery, an acute inflammatory disease causing the death of more than one million humans per year. The enzyme tRNA-guanine transglycosylase (TGT) catalyzes the base exchange of the genetically encoded guanine at the wobble position of particular tRNAs by the modified base preQ1. Further modification of preQ1 and the final incorporation of queuine into the tRNAs lead to the development of the virulence phenotype of Shigella, thus making TGT a suitable drug target. The enzyme is biologically active only as a homodimer, as one monomer subunit performs the catalytic base-exchange reaction while the second subunit is required to position the tRNA substrate in the correct orientation.

protein dimerization | homodimer | MO-P-068