Isomorphic coalescence of aster cores formedin vitrofrom microtubules and kinesin motors

Abstract

We report fluorescence microscopy studies of the formation of aster-like structures emerging from a cellular element-based active system and a novel analysis of the aster condensation. The system consists of rhodamine labeled microtubules which are dynamically coupled by functionalized kinesin motor proteins cross-linked via streptavidin-coated quantum dots (QDs). The aster-shaped objects contain core structures. The cores are aggregates of the QD-motor protein complexes, and result from the dynamic condensation of sub-clusters that are connected to each other randomly. The structural specificity of the aster core reflects a configuration of the initial connectivity between sub-clusters. Detailed image analysis allows us to extract a novel correlation between the condensation speed and the sub-cluster separation. The size of the core is scaled down during the condensation process, following a power law dependence on the distance between sub-clusters. The exponent of the power law is close to two, as expected from a geometric model. This single exponent common to all the contractile lines implies that there exists a time regime during which an isomorphic contraction of the aster core continues during the condensation process. We analyze the observed contraction by using a model system with potential applicability in a wide range of emergent phenomena in randomly coupled active networks, which are prevalent in the cellular environment.

Remodeling Tau and Prion Proteins Using Nanochaperons

“…Fluorescence Microscopy : Observations were performed with a fluorescence microscope (IX‐71, Olympus) equipped with a CCD camera (ImagEM, Hamamatsu, Adaptor: U‐PMTVC4XIR) as described in the previous literature . Two filter sets were used: XF204 (for rhodamine, Omega optical) and XF305‐1 (for QD655, Omega optical).…”

Synthetic Systems Powered by Biological Molecular Motors

“…A long-term goal in the field is to scale-up molecular force generation and mimic the hierarchic organization of muscle. − Progress has been made in the construction of artificial cilia, where microtubules are cross-linked by kinesin constructs and the resulting microtubule bundles exhibit beating movement , as well as in the construction of contractile networks of motors, filaments, and in some cases microparticles. − However, the creation of ordered arrays of filaments which are actuated by large numbers of motors and then sandwiched into multilayer structures as shown in Figure is still in the conceptual stage . The work of Agayan et al highlighted how thermal forces oppose the dynamic assembly of ordered arrays .…”