The cytoskeleton facilitates many essential cellular tasks, such as motility and division. Cytoskeletal ensembles experience emergent mechanics where the sum of its single-molecule component properties does not reflect mechanics as the whole ensemble. The design principles and mechanisms behind this emergent behavior are not well understood. Through previous optical trapping work in the lab, we hypothesize that cytoskeletal filaments can function as force sensors and influence motor protein behavior. We developed an innovative approach to understanding these emergent mechanics using a quartz crystal microbalance with dissipation monitoring (QCM-D) to measure viscoelastic changes in actomyosin bundles. Previous work demonstrated that the QCM-D detects altered bundle mechanics due to concentration-dependent myosin activity and nucleotide state, supporting the concept of actin as a mechanical force-feedback sensor. ADP rigidifies actomyosin bundles by promoting strong myosin binding states that then act as static crosslinkers, whereas ATP maintains compliance through dynamic motor turnover. Building on this foundation, we investigate how actin crosslinkers influence bundle mechanics and their interactions with motor proteins using QCM-D, hypothesizing that crosslinkers of different sizes and compliances tune mechanical feedback in actomyosin assemblies.
Amari et al. (2026) studied this question.