Vesicles of lipid bilayer can adopt a variety of shapes due to different coating proteins.The ability of proteins to reshape membrane is typically characterized by inducing spontaneous curvature of the membrane at the...Vesicles of lipid bilayer can adopt a variety of shapes due to different coating proteins.The ability of proteins to reshape membrane is typically characterized by inducing spontaneous curvature of the membrane at the coated area.BAR family proteins are known to have a crescent shape and can induce membrane curvature along their concaved body axis but not in the perpendicular direction.We model this type of proteins as a rod-shaped molecule with an orientation and induce normal curvature along its orientation in the tangential plane of the membrane surface.We show how a ring of these proteins reshapes an axisymmetric vesicle when the protein curvature or orientation is varied.A discontinuous shape transformation from a protrusion shape without a neck to a one with a neck is found.Increasing the rigidity of the protein ring is able to smooth out the transition.Furthermore,we show that varying the protein orientation is able to induce an hourglass-shaped neck,which is significantly narrower than the reciprocal of the protein curvature.Our results offer a new angle to rationalize the helical structure formed by many proteins that carry out membrane fission functions.展开更多
Cell division is a fundamental biological process in which a parent cell divides into two daughter cells.The cell cortex,a thin layer primarily composed of actin filaments and myosin motors beneath the plasma membrane...Cell division is a fundamental biological process in which a parent cell divides into two daughter cells.The cell cortex,a thin layer primarily composed of actin filaments and myosin motors beneath the plasma membrane,plays a critical role in ensuring proper cell division.In this study,we apply a hydrodynamic model to describe the actin cortex as an active nematic surface,incorporating orientational order arising from actin filament alignment and anisotropic active stress produced by myosin motors.By analyzing the linearized dynamics,we investigate how shape,flow,and stress regulators evolve over time when the surface deviates slightly from a sphere.Our findings reveal that the active alignment of actin filaments,often overlooked in previous studies,is crucial for successful division.Furthermore,we demonstrate that a cortical chiral flow naturally emerges as a consequence of this active alignment.Overall,our results provide a mechanistic explanation for key phenomena observed during cell division,offering new insights into the role of active stress and filament alignment in cortical dynamics.展开更多
基金support from the the National Natural Science Foundation of China(Grant Nos.12474199(RM)and 12374213(YC))Fundamental Research Funds for Central Universities of China(Grant No.20720240144(RM))111 Project(Grant No.B16029).
文摘Vesicles of lipid bilayer can adopt a variety of shapes due to different coating proteins.The ability of proteins to reshape membrane is typically characterized by inducing spontaneous curvature of the membrane at the coated area.BAR family proteins are known to have a crescent shape and can induce membrane curvature along their concaved body axis but not in the perpendicular direction.We model this type of proteins as a rod-shaped molecule with an orientation and induce normal curvature along its orientation in the tangential plane of the membrane surface.We show how a ring of these proteins reshapes an axisymmetric vesicle when the protein curvature or orientation is varied.A discontinuous shape transformation from a protrusion shape without a neck to a one with a neck is found.Increasing the rigidity of the protein ring is able to smooth out the transition.Furthermore,we show that varying the protein orientation is able to induce an hourglass-shaped neck,which is significantly narrower than the reciprocal of the protein curvature.Our results offer a new angle to rationalize the helical structure formed by many proteins that carry out membrane fission functions.
基金support from the National Nat-ural Science Foundation of China(Grant No.12474199)the Fundamental Research Funds for Central Universities of China(Grant No.20720240144),and 111 Project(B16029).
文摘Cell division is a fundamental biological process in which a parent cell divides into two daughter cells.The cell cortex,a thin layer primarily composed of actin filaments and myosin motors beneath the plasma membrane,plays a critical role in ensuring proper cell division.In this study,we apply a hydrodynamic model to describe the actin cortex as an active nematic surface,incorporating orientational order arising from actin filament alignment and anisotropic active stress produced by myosin motors.By analyzing the linearized dynamics,we investigate how shape,flow,and stress regulators evolve over time when the surface deviates slightly from a sphere.Our findings reveal that the active alignment of actin filaments,often overlooked in previous studies,is crucial for successful division.Furthermore,we demonstrate that a cortical chiral flow naturally emerges as a consequence of this active alignment.Overall,our results provide a mechanistic explanation for key phenomena observed during cell division,offering new insights into the role of active stress and filament alignment in cortical dynamics.
