FTSN, A LATE RECRUIT TO THE SEPTUM IN ESCHERICHIA-COLI

The localization of FtsN in Escherichia coli was investigated by immun ofluorescence microscopy. FtsN is an essential cell division protein w ith a simple bitopic topology, a short N-terminal cytoplasmic segment fused to a large carboxy periplasmic domain through a single transmemb rane domain. FtsN was found to localize to the septum in a ring patter n similar to that observed for FtsZ and FtsA, although the frequency o f cells with rings was less. A MalG-FtsN fusion was also localized to the septum, indicating that the information for FtsN localization is s upplied by its periplasmic domain. FtsN localization was dependent upo n the prior localization of FtsZ and FtsA and required the function of FtsI and FtsQ. Consistent with FtsN functioning after FtsZ, Z rings w ere observed in a mutant depleted of FtsN.