Fluorescence Imaging With One Nanometer Accuracy: Determination of How Processive Motors Walk
Yildiz, Ahmet
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Permalink
https://hdl.handle.net/2142/85439
Description
Title
Fluorescence Imaging With One Nanometer Accuracy: Determination of How Processive Motors Walk
Author(s)
Yildiz, Ahmet
Issue Date
2004
Doctoral Committee Chair(s)
Selvin, Paul R.
Department of Study
Biophysics and Computational Biology
Discipline
Biophysics and Computational Biology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Optics
Language
eng
Abstract
"Cargo transportation within a cell is accomplished by processive molecular motors. Motor proteins haul the cargo and transport it over long distances by taking hundreds of consecutive steps without dissociating from the cytoskeleton. Myosin V, myosin VI, and kinesin are well known processive motors. Structurally, these motors are dimeric having two motor heads, two legs, and a common stalk. Whether they move by a ""hand-over-hand"" or an ""inchworm"" model has been a controversial topic. In the hand-over-hand model, a motor moves by swapping its heads similarly to human walking, while the inchworm model states that one head leads and the other head follows. To distinguish between these two models, we aim to watch the movement of an individual head while a motor walks on its respective track in vitro. The measurement requires nanometer range spatial resolution with a nanometer-sized probe. We developed a new fluorescence technique that is able to locate the position of a single fluorescent dye within ∼1 nm on a glass surface. The technique of FIONA (Fluorescence Imaging with One Nanometer Accuracy) is achieved by acquiring high signal-to-noise ratio images and locating the center via fitting the images to a two-dimensional Gaussian. We have attached a single fluorescent dye to the head region of a motor and tracked the position of the dye while the motor walks. For myosin V, myosin VI, and kinesin, we found that the dye alternates between moving twice the stalk step size and staying fixed, which confirms a hand-over-hand motion."
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