CHARACTERIZATION OF 3 DIFFERENT LYTIC TRANSGLYCOSYLASES IN ESCHERICHIA-COLI

Two lytic transglycosylases, releasing 1,6-anhydromuropeptides from mu rein sacculi are present in a mutant deleted for the soluble lytic tra nsglycosylase 70 (Slt70). Thus, there are three different lytic transg lycosylases in Escherichia coli. One of the remaining enzymes is solub le and one is a membrane protein that can be solubilized by 2% Triton X-100 in 0.5 M NaCl. Both enzymes are exo-muramidases. Only the membra ne enzyme, but not the soluble ones, hydrolyses isolated murein glycan strands (poly-GlcNAc-MurNAc). While the soluble enzymes are inhibited by the muropeptide TetraTriLysArg(dianhydro), the membrane enzyme is not. The antibiotic bulgecin that inhibits Slt70 does not inhibit the lytic transglycosylases present in the slt70 deletion mutant.