Measuring molecular motor forces in VIVO

Implications for tug-of-war models of bidirectional transport

Christina Leidel, Rafael A. Longoria, Franciso Marquez Gutierrez, George Shubeita

    Research output: Contribution to journalArticle

    Abstract

    Molecular motor proteins use the energy released from ATP hydrolysis to generate force and haul cargoes along cytoskeletal filaments. Thus, measuring the force motors generate amounts to directly probing their function. We report on optical trapping methodology capable of making precise in vivo stall-force measurements of individual cargoes hauled by molecular motors in their native environment. Despite routine measurement of motor forces in vitro, performing and calibrating such measurements in vivo has been challenging. We describe the methodology recently developed to overcome these difficulties, and used to measure stall forces of both kinesin-1 and cytoplasmic dynein-driven lipid droplets in Drosophila embryos. Critically, by measuring the cargo dynamics in the optical trap, we find that there is memory: it is more likely for a cargo to resume motion in the same direction - rather than reverse direction - after the motors transporting it detach from the microtubule under the force of the optical trap. This suggests that only motors of one polarity are active on the cargo at any instant in time and is not consistent with the tug-of-war models of bidirectional transport where both polarity motors can bind the microtubules at all times. We further use the optical trap to measure in vivo the detachment rates from microtubules of kinesin-1 and dynein-driven lipid droplets. Unlike what is commonly assumed, we find that dynein's but not kinesin's detachment time in vivo increases with opposing load. This suggests that dynein's interaction with microtubules behaves like a catch bond.

    Original languageEnglish (US)
    Pages (from-to)492-500
    Number of pages9
    JournalBiophysical Journal
    Volume103
    Issue number3
    DOIs
    StatePublished - Aug 8 2012

    Fingerprint

    Optical Tweezers
    Dyneins
    Microtubules
    Kinesin
    Molecular Motor Proteins
    Cytoplasmic Dyneins
    Cytoskeleton
    Drosophila
    Hydrolysis
    Embryonic Structures
    Adenosine Triphosphate
    Warfare
    Lipid Droplets
    Direction compound

    ASJC Scopus subject areas

    • Biophysics

    Cite this

    Measuring molecular motor forces in VIVO : Implications for tug-of-war models of bidirectional transport. / Leidel, Christina; Longoria, Rafael A.; Gutierrez, Franciso Marquez; Shubeita, George.

    In: Biophysical Journal, Vol. 103, No. 3, 08.08.2012, p. 492-500.

    Research output: Contribution to journalArticle

    Leidel, Christina ; Longoria, Rafael A. ; Gutierrez, Franciso Marquez ; Shubeita, George. / Measuring molecular motor forces in VIVO : Implications for tug-of-war models of bidirectional transport. In: Biophysical Journal. 2012 ; Vol. 103, No. 3. pp. 492-500.
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