Identification of FtsW as a transporter of lipid-linked cell wall precursors across the membrane

Bacterial cell growth necessitates synthesis of peptidoglycan. Assembly of this major constituent of the bacterial cell wall is a multistep process starting in the cytoplasm and ending in the exterior cell surface. The intracellular part of the pathway results in the production of the membrane-anchored cell wall precursor, Lipid II. After synthesis this lipid intermediate is translocated across the cell membrane. The translocation (flipping) step of Lipid II was demonstrated to require a specific protein (flippase). Here, we show that the integral membrane protein FtsW, an essential protein of the bacterial division machinery, is a transporter of the lipid-linked peptidoglycan precursors across the cytoplasmic membrane. Using Escherichia coli membrane vesicles we found that transport of Lipid II requires the presence of FtsW, and purified FtsW induced the transbi-layer movement of Lipid II in model membranes. This study provides the first biochemical evidence for the involvement of an essential protein in the transport of lipid-linked cell wall precursors across biogenic membranes. The EMBO Journal (2011) 30, 1425-1432. doi:10.1038/emboj.2011.61; Published online 8 March 2011 Subject Categories: membranes & transport; cell & tissue architecture