Ca2+-tunable mechanics and recoil in reconstituted Tcb2 networks
Abstract
Tetrahymena calcium-binding protein (Tcb2) forms Ca2+-responsive networks that exhibit contractile behavior, yet how Ca2+ concentration controls their local mechanical response remains poorly understood. Here, we use optical tweezers to perform active microrheology on reconstituted Tcb2 networks inside a microfluidic device that enables precise control of Ca2+ concentration, allowing systematic tuning of network structure and mechanics. We find that increasing Ca2+ from 1 to 100~mM enhances the effective stiffness by nearly two orders of magnitude, from ∼1×10−3 to ∼7×10−2~pN/nm, corresponding to a transition from a viscosity-dominated to a more elastic and mechanically robust network. Recoil assays further reveal rapid release of stored elastic energy following deformation. After two orthogonal pulls, the bead recoils along the diagonal rather than retracing the loading path, indicating that stresses from different directions combine to produce a resultant restoring response. These results establish Tcb2 networks as a minimal, tunable system for probing chemomechanical coupling and viscoelasticity in Ca2+-regulated protein networks.
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BibTeX
@misc{lei2026ca2tunable,
title = {{Ca$^2+$-tunable mechanics and recoil in reconstituted Tcb2 networks}},
author = {Xiangting Lei and K. R. Prathyusha and Carlos Floyd and Jerry Honts and Saad Bhamla},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.38667},
eprint = {2609.38667},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.38667},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Ca^2+-tunable mechanics and recoil in reconstituted Tcb2 networks
AU - Xiangting Lei
AU - K. R. Prathyusha
AU - Carlos Floyd
AU - Jerry Honts
AU - Saad Bhamla
PY - 2026
DA - 2026/09/29
PB - arXiv
DO - 10.48550/arxiv.2609.38667
UR - https://arxiv.org/abs/2609.38667
AB - Tetrahymena calcium-binding protein (Tcb2) forms Ca^2+-responsive networks that exhibit contractile behavior, yet how Ca^2+ concentration controls their local mechanical response remains poorly understood. Here, we use optical tweezers to perform active microrheology on reconstituted Tcb2 networks inside a microfluidic device that enables precise control of Ca^2+ concentration, allowing systematic tuning of network structure and mechanics. We find that increasing Ca^2+ from 1 to 100~mM enhances the effective stiffness by nearly two orders of magnitude, from ∼1×10^−3 to ∼7×10^−2~pN/nm, corresponding to a transition from a viscosity-dominated to a more elastic and mechanically robust network. Recoil assays further reveal rapid release of stored elastic energy following deformation. After two orthogonal pulls, the bead recoils along the diagonal rather than retracing the loading path, indicating that stresses from different directions combine to produce a resultant restoring response. These results establish Tcb2 networks as a minimal, tunable system for probing chemomechanical coupling and viscoelasticity in Ca^2+-regulated protein networks.
ER -