The bacterial cytoskeleton: an intermediate filament-like function in cell shape

Cell. 2003 Dec 12;115(6):705-13. doi: 10.1016/s0092-8674(03)00935-8.


Various cell shapes are encountered in the prokaryotic world, but how they are achieved is poorly understood. Intermediate filaments (IFs) of the eukaryotic cytoskeleton play an important role in cell shape in higher organisms. No such filaments have been found in prokaryotes. Here, we describe a bacterial equivalent to IF proteins, named crescentin, whose cytoskeletal function is required for the vibrioid and helical shapes of Caulobacter crescentus. Without crescentin, the cells adopt a straight-rod morphology. Crescentin has characteristic features of IF proteins including the ability to assemble into filaments in vitro without energy or cofactor requirements. In vivo, crescentin forms a helical structure that colocalizes with the inner cell curvatures beneath the cytoplasmic membrane. We propose that IF-like filaments of crescentin assemble into a helical structure, which by applying its geometry to the cell, generates a vibrioid or helical cell shape depending on the length of the cell.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / isolation & purification*
  • Caulobacter crescentus / metabolism*
  • Caulobacter crescentus / ultrastructure
  • Cell Membrane / metabolism
  • Cell Size / physiology
  • Eukaryotic Cells / metabolism
  • Eukaryotic Cells / ultrastructure
  • Evolution, Molecular
  • Intermediate Filament Proteins / genetics
  • Intermediate Filament Proteins / isolation & purification*
  • Intermediate Filaments / metabolism*
  • Intermediate Filaments / ultrastructure
  • Protein Conformation


  • Bacterial Proteins
  • Intermediate Filament Proteins