Spatial resolution of two bacterial cell division proteins: ZapA recruits ZapB to the inner face of the Z-ring

Mol Microbiol. 2010 Jun;76(6):1514-26. doi: 10.1111/j.1365-2958.2010.07183.x. Epub 2010 May 11.


FtsZ, the essential regulator of bacterial cell division, is a dynamic cytoskeletal protein that forms helices that condense into the Z-ring prior to division. Two small coiled-coil proteins, ZapA and ZapB, are both recruited early to the Z-ring. We show here that ZapB is recruited to the Z-ring by ZapA. A direct interaction between ZapA and ZapB is supported by bacterial two-hybrid and in vitro interaction assays. Using high-resolution 3-D reconstruction microscopy, we find that, surprisingly, ZapB is located inside the Z-ring in virtually all cells investigated. We propose a molecular model in which ZapA increases lateral interactions between FtsZ proto-filaments and ZapB mediates further stabilization of this interaction by cross-linking ZapA molecules bound to adjacent FtsZ proto-filaments. Gene deletion and complementation assays show that ZapB can mitigate cell division and Z-ring assembly defects even in the absence of ZapA, raising the possibility that ZapB stimulates Z-ring assembly by two different mechanisms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / analysis*
  • Carrier Proteins / analysis*
  • Cell Cycle Proteins / analysis*
  • Cell Division*
  • Cytoskeletal Proteins / analysis*
  • Escherichia coli / chemistry*
  • Escherichia coli / physiology*
  • Escherichia coli Proteins / analysis*
  • Gene Deletion
  • Genetic Complementation Test
  • Imaging, Three-Dimensional
  • Microscopy
  • Models, Biological
  • Protein Binding


  • Bacterial Proteins
  • Carrier Proteins
  • Cell Cycle Proteins
  • Cytoskeletal Proteins
  • Escherichia coli Proteins
  • FtsZ protein, Bacteria
  • ZapA protein, E coli
  • ZapB protein, E coli