FtsA mutants impaired for self-interaction bypass ZipA suggesting a model in which FtsA's self-interaction competes with its ability to recruit downstream division proteins

Authors

  • Sebastien Pichoff,

    Corresponding author
    1. Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
      E-mail spichoff@kumc.edu; Tel. (+1) 913 588 7398; Fax (+1) 913 588 7295.
    Search for more papers by this author
  • Bang Shen,

    1. Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA.
    Search for more papers by this author
  • Bradley Sullivan,

    1. Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
    Search for more papers by this author
  • Joe Lutkenhaus

    1. Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
    Search for more papers by this author

E-mail spichoff@kumc.edu; Tel. (+1) 913 588 7398; Fax (+1) 913 588 7295.

Summary

Z-ring assembly requires polymers of the tubulin homologue FtsZ to be tethered to the membrane. Although either ZipA or FtsA is sufficient to do this, both of these are required for recruitment of downstream proteins to form a functional cytokinetic ring. Gain of function mutations in ftsA, such as ftsA* (ftsA-R286W), bypass the requirement for ZipA suggesting that this atypical, well-conserved, actin homologue has a more critical role in Z-ring function. FtsA forms multimers both in vitro and in vivo, but little is known about the role of FtsA polymerization. In this study we identify FtsA mutants impaired for self-interaction. Such mutants are able to support Z-ring assembly and are also able to bypass the requirement for ZipA. These mutants, including FtsA*, have reduced ability to self-interact but interact normally with FtsZ and are less toxic if overexpressed. These results do not support a model in which FtsA monomers antagonize FtsZ polymers. Instead, we propose a new model in which FtsA self-interaction competes with its ability to recruit downstream proteins. In this model FtsA self-interaction at the Z ring is antagonized by ZipA, allowing unpolymerized FtsA to recruit downstream proteins such as FtsN.

Ancillary