FtsA G50E mutant suppresses the essential requirement for FtsK during bacterial cell division in Escherichia coli

In Escherichia coli, the N-terminal domain of the essential protein FtsK (FtsKN) is proposed to modulate septum formation through the formation of dynamic and essential protein interactions with both the Z-ring and late-stage division machinery. Using genomic mutagenesis, complementation analysis, and in vitro pull-down assays, we aimed to identify protein interaction partners of FtsK essential to its function during division. Here, we identified the cytoplasmic Z-ring membrane anchoring protein FtsA as a direct protein–protein interaction partner of FtsK. Random genomic mutagenesis of an ftsK temperature-sensitive strain of E. coli revealed an FtsA point mutation (G50E) that is able to fully restore normal cell growth and morphology, and further targeted site-directed mutagenesis of FtsA revealed several other point mutations capable of fully suppressing the essential requirement for functional FtsK. Together, this provides insight into a potential novel co-complex formed between these components during division and suggests FtsA may directly impact FtsK function.