A formin-nucleated actin aster concentrates cell wall hydrolases for cell fusion in fission yeast

J Cell Biol. 2015 Mar 30;208(7):897-911. doi: 10.1083/jcb.201411124.


Cell-cell fusion is essential for fertilization. For fusion of walled cells, the cell wall must be degraded at a precise location but maintained in surrounding regions to protect against lysis. In fission yeast cells, the formin Fus1, which nucleates linear actin filaments, is essential for this process. In this paper, we show that this formin organizes a specific actin structure-the actin fusion focus. Structured illumination microscopy and live-cell imaging of Fus1, actin, and type V myosins revealed an aster of actin filaments whose barbed ends are focalized near the plasma membrane. Focalization requires Fus1 and type V myosins and happens asynchronously always in the M cell first. Type V myosins are essential for fusion and concentrate cell wall hydrolases, but not cell wall synthases, at the fusion focus. Thus, the fusion focus focalizes cell wall dissolution within a broader cell wall synthesis zone to shift from cell growth to cell fusion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Actins / metabolism
  • Cell Fusion
  • Cell Membrane / metabolism
  • Cell Wall / metabolism*
  • Cytoskeletal Proteins / metabolism
  • Hydrolases / metabolism*
  • Myosin Type V / metabolism*
  • Myosins / metabolism
  • Schizosaccharomyces / cytology*
  • Schizosaccharomyces pombe Proteins / metabolism*


  • Actins
  • Cytoskeletal Proteins
  • Schizosaccharomyces pombe Proteins
  • fus1 protein, S pombe
  • Hydrolases
  • Myo52 protein, S pombe
  • Myosin Type V
  • Myo51 protein, S pombe
  • Myosins