C-terminal domain of ZipA, a component of cell division in E.coli. It interacts with the FtsZ protein in one of the initial steps of septum formation. The structure of this domain is composed of three alpha-helices and a beta-sheet consisting of six antiparallel beta-strands.
This entry represents the ZipA C-terminal domain. ZipA, a membrane-anchored protein, is an essential cell division protein involved in septum formation [ (PUBMED:9008158) (PUBMED:9864327) ]. FtsA and the C-terminal domain of ZipA bind FtsZ, a homologue of eukaryotic tubulins and a major component of the bacterial septal ring [ (PUBMED:10209756) ], at the prospective division site. This is followed by the sequential addition of FtsK, FtsQ, FtsL, FtsW, FtsI, and FtsN [ (PUBMED:11163134) (PUBMED:11948172) (PUBMED:11847116) ]. ZipA contains three domains: a short N-terminal membrane-anchored domain, a central P/Q domain that is rich in proline and glutamine and a C-terminal domain, which comprises almost half the protein. The structure of the C-terminal domain is an alpha-beta fold with three alpha helices and a beta sheet of six antiparallel beta strands. The major loops protruding from the beta sheet surface are thought to form a binding site for FtsZ [ (PUBMED:10924108) ].
Recruitment of ZipA to the septal ring of Escherichia coli is dependent on FtsZ and independent of FtsA.
J Bacteriol. 1999; 181: 167-76
Display abstract
Cell division in prokaryotes is mediated by the septal ring. In Escherichia coli, this organelle consists of several essential division proteins, including FtsZ, FtsA, and ZipA. To gain more insight into how the structure is assembled, we studied the interdependence of FtsZ, FtsA, and ZipA localization using both immunofluorescence and Gfp tagging techniques. To this end, we constructed a set of strains allowing us to determine the cellular location of each of these three proteins in cells from which one of the other two had been specifically depleted. Our results show that ZipA fails to accumulate in a ring shape in the absence of FtsZ. Conversely, depletion of ZipA does not abolish formation of FtsZ rings but leads to a significant reduction in the number of rings per unit of cell mass. In addition, ZipA does not appear to require FtsA for assembly into the septal ring and vice versa. It is suggested that septal ring formation starts by assembly of the FtsZ ring, after which ZipA and FtsA join this structure in a mutually independent fashion through direct interactions with the FtsZ protein.
Recruitment of ZipA to the division site by interaction with FtsZ.
Mol Microbiol. 1999; 31: 1853-61
Display abstract
ZipA is an essential cell division protein in Escherichia coli that is recruited to the division site early in the division cycle. As it is anchored to the membrane and interacts with FtsZ, it is a candidate for tethering FtsZ filaments to the membrane during the formation of the Z ring. In this study, we have investigated the requirements for ZipA localization to the division site. ZipA requires FtsZ, but not FtsA or FtsI, to be localized, indicating that it is recruited by FtsZ. Consistent with this, apparently normal Z rings are formed in the absence of ZipA. The interaction between FtsZ and ZipA occurs through their carboxy-terminal domains. Although a MalE-ZipA fusion binds to FtsZ filaments, it does not affect the GTPase activity or dynamics of the filaments. These results are consistent with ZipA acting after Z ring formation, possibly to link the membrane to FtsZ filaments during invagination of the septum.
Direct binding of FtsZ to ZipA, an essential component of the septal ring structure that mediates cell division in E. coli.
Cell. 1997; 88: 175-85
Display abstract
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.
