Inhibition of cell membrane ingression at the division site by cell walls in fission yeast

Abstract

Eukaryotic cells assemble an actomyosin ring during cytokinesis to function as a force-generating machine to drive membrane invagination, and to counteract the intracellular pressure and the cell surface tension. How the extracellular matrix affects actomyosin ring contraction has not been fully explored. While studying the S. pombe 1,3− β-glucan-synthase mutant cps1-191, which is defective in division septum synthesis and arrests with a stable actomyosin ring and, we found that weakening of the extracellular glycan matrix caused the generated spheroplasts to divide at the non-permissive condition. This non-medial slow division was dependent on a functional actomyosin ring and vesicular trafficking, but independent of normal septum synthesis. Interestingly, the high intracellular turgor pressure appears to play minimal roles in inhibiting ring contraction in the absence of cell wall remodeling in cps1-191 mutants as decreasing the turgor pressure alone did not enable spheroplast division. We propose that during cytokinesis, the extracellular glycan matrix restricts actomyosin ring contraction and membrane ingression, and remodeling of the extracellular components through division septum synthesis relieves the inhibition and facilitates actomyosin ring contraction.

Processes Controlling the Contractile Ring during Cytokinesis in Fission Yeast, Including the Role of ESCRT Proteins

“…Recently, Chew et al [54] investigated the effects of the extracellular glycan matrix on ACR contraction. They used a fission yeast thermosensitive mutant cps1-191, defective in beta-glucan-synthase septum synthesis.…”

Roles of ESCRT-III polymers in cell division across the tree of life

“…In this case, it is external cell wall deposition rather than cytoskeletal remodelling that provides the force required to cut cells into two. This is true for fission yeast cells, where organised deposition of the septum depends on the actomyosin ring [ 10 – 12 ], and for many bacteria, where wall synthesis depends on a tubulin-like polymer, FtsZ, often working together with actin-like filaments [ 13 – 15 ]. By contrast, in cells with a soft boundary, like animal cells, Dictyostelium [ 16 ] and most archaea [ 17 ], the forces required for division are generated by cytoskeletal polymers themselves as they pull on the limiting membrane from the inside [ 18 , 19 ].…”

Spheroplasts preparation boosts the catalytic potential of a squalene-hopene cyclase

“…A compromise between cell-free enzymes and whole cells is offered by spheroplast preparations: these are gram-negative bacterial cells in which the outer membrane has been partially or completely removed. Despite some applications of spheroplasts reported in biomedicine and cell biology research, their potential role as biocatalysts has been overlooked 17 , 18 .…”