MutL_Trans_MutL: transducer domain, having a ribosomal S5 domain 2-like fold, found in proteins similar to Escherichia coli MutL. EcMutL belongs to the DNA mismatch repair (MutL/MLH1/PMS2) family. This transducer domain is homologous to the second domain of the DNA gyrase B subunit, which is known to be important in nucleotide hydrolysis and the transduction of structural signals from the ATP-binding site to the DNA breakage/reunion regions of the enzymes. It has been suggested that during initiation of DNA mismatch repair in E. coli, the mismatch recognition protein MutS recruits MutL in the presence of ATP. The MutS(ATP)-MutL ternary complex formed, then recruits the latent endonuclease MutH. Prokaryotic MutS and MutL are homodimers.