Counting actin in contractile rings reveals novel contributions of cofilin and type II myosins to fission yeast cytokinesis.

Abstract

Cytokinesis by animals, fungi, and amoebas depends on actomyosin contractile rings, which are stabilized by continuous turnover of actin filaments. Remarkably little is known about the amount of polymerized actin in contractile rings, so we used low concentrations of GFP-Lifeact to count total polymerized actin molecules in the contractile rings of live fission yeast cells. Contractile rings of wild-type cells accumulated polymerized actin molecules at 4900/min to a peak number of ∼198,000 followed by a loss of actin at 5400/min throughout ring constriction. In adf1-M3 mutant cells with cofilin that severs actin filaments poorly, contractile rings accumulated polymerized actin at twice the normal rate and eventually had almost twofold more actin along with a proportional increase in type II myosins Myo2, Myp2, and formin Cdc12. Although 30% of adf1-M3 mutant cells failed to constrict their rings fully, the rest lost actin from the rings at the wild-type rates. Mutations of type II myosins Myo2 and Myp2 reduced contractile ring actin filaments by half and slowed the rate of actin loss from the rings.

• Authors: Mamata Malla, Thomas D Pollard, Qian Chen
• Journal: Molecular biology of the cell (Mol Biol Cell) Vol. 33 Issue 6 Pg. ar51 (05 15 2022) ISSN: 1939-4586 [Electronic] United States
• PMID: 34613787 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Actin Depolymerizing Factors
• Actins
• MYO2 protein, S pombe
• Myp2 protein, S pombe
• Schizosaccharomyces pombe Proteins
• Myosin Type II
• Myosin Heavy Chains
• Myosins

Topics

• Actin Cytoskeleton
• Actin Depolymerizing Factors
• Actins
• Animals
• Cytokinesis (genetics)
• Myopia
• Myosin Heavy Chains (genetics)
• Myosin Type II (genetics)
• Myosins
• Schizosaccharomyces (genetics)
• Schizosaccharomyces pombe Proteins (genetics)