Spatial resolution of two bacterial cell division proteins: ZapA recruits ZapB to the inner face of the Z-ring.
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.
Galli
Elisa
E
Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle NE2 4HH, UK.
Gerdes
Kenn
K
D001426:Bacterial Proteins / Q000032:analysis*; D002352:Carrier Proteins / Q000032:analysis*; D018797:Cell Cycle Proteins / Q000032:analysis*; D002455:Cell Division; D003598:Cytoskeletal Proteins / Q000032:analysis*; D004926:Escherichia coli / Q000737:chemistry* / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000032:analysis*; D017353:Gene Deletion; D005816:Genetic Complementation Test; D021621:Imaging, Three-Dimensional; D008853:Microscopy; D008954:Models, Biological; D011485:Protein Binding
D001426:Bacterial Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D029968:Escherichia coli Proteins; C071525:FtsZ protein, Bacteria; C520744:ZapA protein, E coli; C553097:ZapB protein, E coli