Title : Transformation of ActoHMM Assembly Confined in Cell-Sized Liposome

Language: English
Type: Article
Authors: Kingo Takiguchi, Makiko Negishi, Yohko Tanaka-Takiguchi, Michio Homma and Kenichi Yoshikawa
Journal: Langmuir
ISSN: 0743-7463
Volume: 27
Number: 18
Month: 9
Year: 2011
Actual year: 2011
Pages: 11528-11535
doi:   10.1021/la2016287
Abstract: To construct a simple model of a cellular system equipped with motor proteins, cell-sized giant liposomes encapsulating various amounts of actoHMM, the complexes of actin filaments (F-actin) and heavy meromyosin (HMM, an actin-related molecular motor), with a depletion reagent to mimic the crowding effect of inside of living cell, were prepared. We adapted the methodology of the spontaneous transfer of water-in-oil (W/O) droplets through a phospholipid monolayer into the bulk aqueous phase and successfully prepared stable giant liposomes encapsulating the solution with physiological salt concentration containing desired concentrations of actoHMM, which had been almost impossible to obtain using currently adapted methodologies such as natural swelling and electro-formation on an electrode. We then examined the effect of ATP on the cytoskeleton components confined in those cell-sized liposomes, since ATP is known to drive the sliding motion for actoHMM. We added α-hemolysin, a bacterial membrane pore-forming toxin, to the bathing solution and obtained liposomes with the protein pores embedded on the bilayer membrane to allow the transfer of ATP inside the liposomes. We show that, by the ATP supply, the actoHMM bundles inside the liposomes exhibit specific changes in spatial distribution, caused by the active sliding between F-actin and HMM. Interestingly, all F-actins localized around the inner periphery of liposomes smaller than a critical size. Whereas in the bulk solution and also in larger liposomes, the actin bundles formed aster-like structures under the same conditions.

"Transformation of ActoHMM Assembly Confined in Cell-Sized Liposome"

Kingo Takiguchi, Makiko Negishi, Yohko Tanaka-Takiguchi, Michio Homma and Kenichi Yoshikawa, Langmuir, 27, 11528-11535 (2011)