Mutations to kirromycin resistance occur in the interface of domains I and III of EF-Tu.GTP.

The antibiotic kirromycin inhibits protein synthesis by binding to EF-Tu and preventing its release from the ribosome after GTP hydrolysis. We have isolated and sequenced a collection of kirromycin resistant tuf mutations and identified thirteen single amino acid substitutions at seven different sites in EF-Tu. These have been mapped onto the 3D structures of EF-Tu.GTP and EF-Tu.GDP. In the active GTP form of EF-Tu the mutations cluster on each side of the interface between domains I and III. We propose that this domain interface is the binding site for kirromycin.