Cell division in Chlamydiae 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 CT009 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 CT009 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 CT009 in RodZ deficient Escherichia coli. 
Cellular localization analysis of CT009 showed uniform membrane staining in 
Chlamydia. 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 Chlamydia.