Source data: FtsK is critical for the assembly of the unique divisome complex of the FtsZ-less Chlamydia trachomatis IF images

Chlamydia trachomatis serovar L2 (Ct), an obligate
intracellular bacterium that does not encode FtsZ, divides by a polarized
budding process. In the absence of FtsZ, we show that FtsK, a chromosomal
translocase, is critical for divisome assembly in Ct. Chlamydial
FtsK forms discrete foci at the septum and at the base of the progenitor
mother cell, and our data indicate that FtsK foci at the base of the
mother cell mark the location of nascent divisome complexes that form at
the site where a daughter cell will emerge in the next round of division.
The divisome in Ct has a hybrid composition, containing
elements of the divisome and elongasome from other bacteria, and FtsK is
recruited to nascent divisomes prior to the other chlamydial divisome
proteins assayed, including the PBP2 and PBP3 transpeptidases, and MreB
and MreC. Knocking down FtsK prevents divisome assembly in Ct and
inhibits cell division and septal peptidoglycan synthesis. We further show
that MreB does not function like FtsZ and serves as a scaffold for the
assembly of the Ct divisome. Rather, MreB is one of the last
proteins recruited to the chlamydial divisome, and it is necessary for the
formation of septal peptidoglycan rings. Our studies illustrate the
critical role of chlamydial FtsK in coordinating divisome assembly and
peptidoglycan synthesis in this obligate intracellular bacterial pathogen.