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Proc Natl Acad Sci U S A. 2016 May 3;113(18):4988-93. doi: 10.1073/pnas.1602327113. Epub 2016 Apr 18.

Structures of the nucleoid occlusion protein SlmA bound to DNA and the C-terminal domain of the cytoskeletal protein FtsZ.

Author information

1
Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710 maria.schumacher@duke.edu.
2
Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710.

Abstract

Cell division in most prokaryotes is mediated by FtsZ, which polymerizes to create the cytokinetic Z ring. Multiple FtsZ-binding proteins regulate FtsZ polymerization to ensure the proper spatiotemporal formation of the Z ring at the division site. The DNA-binding protein SlmA binds to FtsZ and prevents Z-ring formation through the nucleoid in a process called "nucleoid occlusion" (NO). As do most FtsZ-accessory proteins, SlmA interacts with the conserved C-terminal domain (CTD) that is connected to the FtsZ core by a long, flexible linker. However, SlmA is distinct from other regulatory factors in that it must be DNA-bound to interact with the FtsZ CTD. Few structures of FtsZ regulator-CTD complexes are available, but all reveal the CTD bound as a helix. To deduce the molecular basis for the unique SlmA-DNA-FtsZ CTD regulatory interaction and provide insight into FtsZ-regulator protein complex formation, we determined structures of Escherichia coli, Vibrio cholera, and Klebsiella pneumonia SlmA-DNA-FtsZ CTD ternary complexes. Strikingly, the FtsZ CTD does not interact with SlmA as a helix but binds as an extended conformation in a narrow, surface-exposed pocket formed only in the DNA-bound state of SlmA and located at the junction between the DNA-binding and C-terminal dimer domains. Binding studies are consistent with the structure and underscore key interactions in complex formation. Combined, these data reveal the molecular basis for the SlmA-DNA-FtsZ interaction with implications for SlmA's NO function and underscore the ability of the FtsZ CTD to adopt a wide range of conformations, explaining its ability to bind diverse regulatory proteins.

KEYWORDS:

FtsZ; SlmA; cell division; nucleoid occlusion; protein–protein interaction

PMID:
27091999
PMCID:
PMC4983851
DOI:
10.1073/pnas.1602327113
[Indexed for MEDLINE]
Free PMC Article

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