Direct binding of FtsZ to ZipA, an essential component of the septal ring structure that mediates cell division in E. coli.

FtsZ is a soluble, tubulin-like GTPase that forms a membrane-associated ring at the division site of bacterial cells. While this ring is thought to drive cell constriction, it is not well understood how it is assembled or how it affects cell wall invagination. Here we report that FtsZ binds directly to a novel integral inner membrane protein in E. coli that we call ZipA. We present genetic and morphological evidence indicating that this interaction is required for cell division, and show that a fluorescent ZipA-Gfp fusion protein is located in a ring structure at the division site, both before and during cell wall invagination. ZipA is an essential component of the division machinery, and, by binding to both FtsZ and the cytoplasmic membrane, is likely to be directly involved in the assembly and/or function of the FtsZ ring.