Chlamydia trachomatis protein CT 009 is a structural and functional homolog to the key morphogenesis component RodZ and interacts with division septal plane localized MreB

Summary Cell division in C hlamydiae is poorly understood as apparent homologs to most conserved bacterial cell division proteins are lacking and presence of elongation (rod shape) associated proteins indicate non‐canonical mechanisms may be employed. The rod‐shape determining protein MreB has been proposed as playing a unique role in chlamydial cell division. In other organisms, MreB is part of an elongation complex that requires RodZ for proper function. A recent study reported that the protein encoded by ORF CT 009 interacts with MreB despite low sequence similarity to RodZ. The studies herein expand on those observations through protein structure, mutagenesis and cellular localization analyses. Structural analysis indicated that CT 009 shares high level of structural similarity to RodZ , revealing the conserved orientation of two residues critical for MreB interaction. Substitutions eliminated MreB protein interaction and partial complementation provided by CT 009 in RodZ deficient E scherichia coli . Cellular localization analysis of CT 009 showed uniform membrane staining in C hlamydia . This was in contrast to the localization of MreB , which was restricted to predicted septal planes. MreB localization to septal planes provides direct experimental observation for the role of MreB in cell division and supports the hypothesis that it serves as a functional replacement for FtsZ in C hlamydia .