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1.
EMBO J ; 43(7): 1244-1256, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38424239

RESUMO

During mitosis, motor proteins and microtubule-associated protein organize the spindle apparatus by cross-linking and sliding microtubules. Kinesin-5 plays a vital role in spindle formation and maintenance, potentially inducing twist in the spindle fibers. The off-axis power stroke of kinesin-5 could generate this twist, but its implications in microtubule organization remain unclear. Here, we investigate 3D microtubule-microtubule sliding mediated by the human kinesin-5, KIF11, and found that the motor caused right-handed helical motion of anti-parallel microtubules around each other. The sidestepping ratio increased with reduced ATP concentration, indicating that forward and sideways stepping of the motor are not strictly coupled. Further, the microtubule-microtubule distance (motor extension) during sliding decreased with increasing sliding velocity. Intriguingly, parallel microtubules cross-linked by KIF11 orbited without forward motion, with nearly full motor extension. Altering the length of the neck linker increased the forward velocity and pitch of microtubules in anti-parallel overlaps. Taken together, we suggest that helical motion and orbiting of microtubules, driven by KIF11, contributes to flexible and context-dependent filament organization, as well as torque regulation within the mitotic spindle.


Assuntos
Cinesinas , Microtúbulos , Humanos , Cinesinas/metabolismo , Microtúbulos/metabolismo , Fuso Acromático/fisiologia , Proteínas Associadas aos Microtúbulos/metabolismo , Mitose
2.
Soft Matter ; 16(47): 10585-10590, 2020 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-33112347

RESUMO

Biomimetic behaviour in artificially created active matter that allows deterministic and controlled motility has become of growing interest in recent years. It is well known that phototrophic bacteria optimize their position with respect to light by phototaxis. Here, we describe how our fully artificial, magnetic and photocatalytic microswimmers undergo a specific type of behaviour that strongly resembles phototaxis: when crossing an illuminated stripe the particles repeatedly turn back towards the light once they reach the dark region, without any obvious reason for the particles to do so. In order to understand the origin of this behaviour we analyze different influences and elucidate through experiments and theoretical considerations that this behavior arises from a combination of orientational stabilization through activity and destabilizing Brownian motion. This interplay shows beautifully how simple physical effects can combine into complex behaviours.


Assuntos
Luz , Fototaxia , Movimento Celular , Movimento (Física) , Fenômenos Físicos
3.
Curr Opin Cell Biol ; 88: 102367, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38735207

RESUMO

Microtubule motors play key roles in cellular functions, such as transport, mitosis and cell motility. Fueled by ATP hydrolysis, they convert chemical energy into mechanical work, which enables their movement on microtubules. While their motion along the long axis of microtubules has been studied extensively, some motors display an off-axis component, which results in helical motion around microtubules and the generation of torque in addition to linear forces. Understanding these nuanced movements expands our comprehension of motor protein dynamics and their impact on cellular processes.


Assuntos
Microtúbulos , Proteínas Motores Moleculares , Torque , Microtúbulos/metabolismo , Microtúbulos/química , Proteínas Motores Moleculares/metabolismo , Proteínas Motores Moleculares/química , Humanos , Animais
4.
Commun Biol ; 7(1): 1187, 2024 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-39313522

RESUMO

Raphid diatoms are one of the few eukaryotes capable of gliding motility, which is remarkably fast and allows for quasi-instantaneous directional reversals. Besides other mechanistic models, it has been suggested that an actomyosin system provides the force for diatom gliding. However, in vivo data on the dynamics of actin and myosin in diatoms are lacking. In this study, we demonstrate that the raphe-associated actin bundles required for diatom movement do not exhibit a directional turnover of subunits and thus their dynamics do not contribute directly to force generation. By phylogenomic analysis, we identified four raphid diatom-specific myosins in Craspedostauros australis (CaMyo51A-D) and investigated their in vivo localization and dynamics through GFP-tagging. Only CaMyo51B-D but not CaMyo51A exhibited coordinated movement during gliding, consistent with a role in force generation. The characterization of raphid diatom-specific myosins lays the foundation for unraveling the molecular mechanisms that underlie the gliding motility of diatoms.


Assuntos
Diatomáceas , Miosinas , Diatomáceas/metabolismo , Diatomáceas/genética , Diatomáceas/fisiologia , Miosinas/metabolismo , Miosinas/genética , Filogenia , Movimento , Actinas/metabolismo , Actinas/genética
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