Lecture

Molecular Motors: Rotary Mechanisms

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In course

BIO-244: Physics of the cell

Living organisms evolve in a physical world: their cells respond to mechanics, electricity and light. In this course, we will describe the behavior and function of cells using physical principles. ...

Description

This lecture explores the coordination of molecular motors in large-scale functions, focusing on calcium signaling triggering motor action. It delves into the mechanisms of myosin II, kinesin, dynein, and myosin V, highlighting their different binding states and velocities. The instructor discusses rotary motors, multiple motor transport in fish melanophores, and the bacterial flagellar motor, emphasizing their unique functionalities. Furthermore, the lecture covers the rotary motor function, ATP-synthase structure, and the impact of pH on motor rotation. Polymerization motors, actin's role in Listeria motility, and segregation by polymerization are also discussed, along with the forces generated by polymerization and the speed of translocation ratcheting.

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Instructor

Alexandre Louis André Persat

Expertise bacterial biophysics and bioengineeringmicrofluidicscellular biomechanics Teaching & PhD PhD Students Jann Lukas Ledergerber, Dea Mariette Müller, Marin Paul Geoffroy Marie Ollagnon, Han-Yi Huang, Alice Pellegrino, Shiro Otaki, Chia-Ni Tsai, Po-Long Hsiao Past EPFL PhD Students Lorenzo Anton-Louis Talà, Xavier Pierrat, Tamara Rossy, Alice Cont, Jeremy Wong, Sourabh Monnappa Kuppanda Jafri, Tania Distler Past EPFL PhD Students as codirector Gabriele Gambardella Courses Fluid mechanics (for SV)

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Related concepts (32)

Motor protein

Motor proteins are a class of molecular motors that can move along the cytoplasm of cells. They convert chemical energy into mechanical work by the hydrolysis of ATP. Flagellar rotation, however, is powered by a proton pump. Motor proteins are the driving force behind most active transport of proteins and vesicles in the cytoplasm. Kinesins and cytoplasmic dyneins play essential roles in intracellular transport such as axonal transport and in the formation of the spindle apparatus and the separation of the chromosomes during mitosis and meiosis.

Microtubule

Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 and 15 nm. They are formed by the polymerization of a dimer of two globular proteins, alpha and beta tubulin into protofilaments that can then associate laterally to form a hollow tube, the microtubule. The most common form of a microtubule consists of 13 protofilaments in the tubular arrangement.

Actin

Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of over 100 μM; its mass is roughly 42 kDa, with a diameter of 4 to 7 nm. An actin protein is the monomeric subunit of two types of filaments in cells: microfilaments, one of the three major components of the cytoskeleton, and thin filaments, part of the contractile apparatus in muscle cells.

Molecular motor

Molecular motors are natural (biological) or artificial molecular machines that are the essential agents of movement in living organisms. In general terms, a motor is a device that consumes energy in one form and converts it into motion or mechanical work; for example, many protein-based molecular motors harness the chemical free energy released by the hydrolysis of ATP in order to perform mechanical work. In terms of energetic efficiency, this type of motor can be superior to currently available man-made motors.

Kinesin

A kinesin is a protein belonging to a class of motor proteins found in eukaryotic cells. Kinesins move along microtubule (MT) filaments and are powered by the hydrolysis of adenosine triphosphate (ATP) (thus kinesins are ATPases, a type of enzyme). The active movement of kinesins supports several cellular functions including mitosis, meiosis and transport of cellular cargo, such as in axonal transport, and intraflagellar transport.

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