Identification of a Novel Interaction Between Cell Division Proteins FtsK and MinD in Escherichia coli
Cell division is a tightly regulated process essential for life. In bacteria, numerous protein-driven mechanisms work in concert to assure the proper distribution of cellular material into resulting daughter cells. Given the increasing threat of antibiotic resistant bacteria, these essential mechanisms have become ideal targets for the development of new antibiotics. The protein FtsK (Filamentous temperature sensitive protein K), a multi-domain inner-membrane protein, is essential for cell division in Escherichia coli however its function is not fully understood. To gain insight into this function, we probed interactions between FtsK and other proteins in the cytoplasm. This was done using in vivo UV cross-linking, which captured proteins in close association with FtsK. Cross-linked proteins were then digested into peptides and analyzed by mass spectrometry, which identified the captured proteins. The results identified MinD, a protein involved in the topological regulation of division site placement, as a potential FtsK interaction partner. This interaction was tested in vitro by combining purified FtsK and MinD in a pulldown assay. The result showed immobilized FtsK was sufficient to bind MinD despite stringent washing. Taken together, these findings provide strong evidence for an interaction between FtsK and MinD, implying a previously unknown link between FtsK and the division regulation machinery.