The bacterial cell-division protein ZipA and its interaction with an FtsZ fragment revealed by X-ray crystallography

• Published in: The EMBO journal 2000-07, Vol.19 (13), p.3179-3191
• Main Authors: Mosyak, Lidia, Zhang, Yan, Glasfeld, Elizabeth, Haney, Steve, Stahl, Mark, Seehra, Jasbir, Somers, William S.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; bacterial cell division; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Carrier Proteins - chemistry; Carrier Proteins - metabolism; Cell Cycle Proteins - chemistry; Cell Cycle Proteins - metabolism; crystal structure; Crystallography; Crystallography, X-Ray; Cytoskeletal Proteins; E coli; Escherichia coli; Escherichia coli - metabolism; Escherichia coli Proteins; FtsZ; FtsZ protein; Models, Molecular; Molecular Sequence Data; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Protein Conformation; Sequence Homology, Amino Acid; single isomorphous replacement; ZipA; ZipA protein
• ISSN: 0261-4189; 1460-2075; 1460-2075
• DOI: 10.1093/emboj/19.13.3179

In Escherichia coli , FtsZ, a homologue of eukaryotic tubulins, and ZipA, a membrane‐anchored protein that binds to FtsZ, are two essential components of the septal ring structure that mediates cell division. Recent data indicate that ZipA is involved in the assembly of the ring by linking FtsZ to the cytoplasmic membrane and that the ZipA‐FtsZ interaction is mediated by their C‐terminal domains. We present the X‐ray crystal structures of the C‐terminal FtsZ‐binding domain of ZipA and a complex between this domain and a C‐terminal fragment of FtsZ. The ZipA domain is a six‐stranded β‐sheet packed against three α‐helices and contains the split β‐α‐β motif found in many RNA‐binding proteins. The uncovered side of the sheet incorporates a shallow hydrophobic cavity exposed to solvent. In the complex, the 17‐residue FtsZ fragment occupies this entire cavity of ZipA and binds as an extended β‐strand followed by α‐helix. An alanine‐scanning mutagenesis analysis of the FtsZ fragment was also performed, which shows that only a small cluster of the buried FtsZ side chains is critical in binding to ZipA.