title: Structure of the Z Ring-associated Protein, ZapD, Bound to the C-terminal Domain of the Tubulin-like Protein, FtsZ, Suggests Mechanism of Z Ring Stabilization through FtsZ Cross-linking.
abstract: Cell division in most bacteria is mediated by the tubulin-like FtsZ protein, which polymerizes in a GTP-dependent manner to form the cytokinetic Z ring. A diverse repertoire of FtsZ-binding proteins affects FtsZ localization and polymerization to ensure correct Z ring formation. Many of these proteins bind the C-terminal domain (CTD) of FtsZ, which serves as a hub for FtsZ regulation. FtsZ ring-associated proteins, ZapA-D (Zaps), are important FtsZ regulatory proteins that stabilize FtsZ assembly and enhance Z ring formation by increasing lateral assembly of FtsZ protofilaments, which then form the Z ring. There are no structures of a Zap protein bound to FtsZ; therefore, how these proteins affect FtsZ polymerization has been unclear. Recent data showed ZapD binds specifically to the FtsZ CTD. Thus, to obtain insight into the ZapD-CTD interaction and how it may mediate FtsZ protofilament assembly, we determined theEscherichia coliZapD-FtsZ CTD structure to 2.67 Å resolution. The structure shows that the CTD docks within a hydrophobic cleft in the ZapD helical domain and adopts an unusual structure composed of two turns of helix separated by a proline kink. FtsZ CTD residue Phe-377 inserts into the ZapD pocket, anchoring the CTD in place and permitting hydrophobic contacts between FtsZ residues Ile-374, Pro-375, and Leu-378 with ZapD residues Leu-74, Trp-77, Leu-91, and Leu-174. The structural findings were supported by mutagenesis coupled with biochemical andin vivostudies. The combined data suggest that ZapD acts as a molecular cross-linking reagent between FtsZ protofilaments to enhance FtsZ assembly.
authors.affiliation: From the Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina 27710, maria.schumacher@duke.edu.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Schumacher
authors.affiliation: the Department of Biology, City College of City University of New York, New York, New York 10031, and.|the Graduate Center, City University of New York, New York, New York 10016.
authors.forename: Kuo-Hsiang
authors.initials: KH
authors.lastname: Huang
authors.affiliation: From the Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina 27710.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Zeng
authors.affiliation: the Department of Biology, City College of City University of New York, New York, New York 10031, and anuj@ccny.cuny.edu.|the Graduate Center, City University of New York, New York, New York 10016.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Janakiraman
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D018797:Cell Cycle Proteins / Q000737:chemistry*; D002470:Cell Survival; D003432:Cross-Linking Reagents / Q000737:chemistry; D018360:Crystallography, X-Ray; D003598:Cytoskeletal Proteins / Q000737:chemistry*; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008027:Light; D008854:Microscopy, Electron; D010641:Phenotype; D010649:Phenylalanine / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D000072417:Protein Domains; D055503:Protein Multimerization; D012542:Scattering, Radiation; D014404:Tubulin / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; D003432:Cross-Linking Reagents; D003598:Cytoskeletal Proteins; D029968:Escherichia coli Proteins; C071525:FtsZ protein, Bacteria; D014404:Tubulin; C574097:ZapD protein, E coli; D010649:Phenylalanine
keywords: FtsZ; X-ray crystallography; ZapD; cell division; cytokinesis; electron microscopy (EM); protein-protein interaction