Nanoscale architecture of the Schizosaccharomyces pombe contractile ring.
- PMID: 28914606[PubMed].
The contractile ring is a complex molecular apparatus important for dividing many eukaryotic cells. Despite knowledge of its composition, the molecular architecture of the ring is not known. Here we applied super-resolution microscopy and FRET to determine the nanoscale spatial organization of Schizosaccharomyces pombe contractile ring components relative to the plasma membrane. As in other membrane-tethered actin structures, contractile ring proteins are stratified relative to the membrane. The lowest layer (0-80 nm) contains membrane-binding scaffolds, formin, and the myosin-II tail. An intermediate zone (80-160 nm) consists of a network of cytokinesis accessory proteins and signaling components that influence cell division. Most interior from the membrane (160-400 nm) is F-actin, myosin motor domains, and an F-actin crosslinker. Circumferentially within the ring, multiple proximal membrane proteins form different sized clusters, while components farther from the membrane are uniformly distributed. This comprehensive organizational map provides a framework for understanding contractile ring function.