Biochemical insights into the interaction network of the essential cell division protein FtsK and peptidoglycan-modifying enzymes in Escherichia coli

ABSTRACT

The protein interactions that govern the regulation of Escherichia coli cell division remain largely uncharacterized. The transmembrane protein FtsK is an essential component of the divisome, a complex network of proteins responsible for septation. The N-terminus (FtsKN) is predicted to modulate septum formation by interacting with peptidoglycan-modifying enzymes DacA, DacC, MltA, and MltB. Gene expression studies and in vitro biochemical analyses reveal that FtsKN selectively modulates the activity and assembly of specific peptidoglycan-modifying enzymes. We show that DacA and DacC have functional relationships with FtsKN that are specific to its inactivation. We demonstrate a novel functional and physical relationship between DacC and FtsKN, implicating FtsKN as a regulator of DacC activity at the division site. Furthermore, we identify MltA as a putative periplasmic effector through which FtsKN coordinates envelope constriction. This work expands the current model of divisome assembly and demonstrates FtsKN’s role as a dynamic regulator of division.