?-Actinin/titin interaction: A dynamic and mechanically stable cluster of bonds in the muscle Z-disk.

ABSTRACT: Stable anchoring of titin within the muscle Z-disk is essential for preserving muscle integrity during passive stretching. One of the main candidates for anchoring titin in the Z-disk is the actin cross-linker ?-actinin. The calmodulin-like domain of ?-actinin binds to the Z-repeats of titin. However, the mechanical and kinetic properties of this important interaction are still unknown. Here, we use a dual-beam optical tweezers assay to study the mechanics of this interaction at the single-molecule level. A single interaction of ?-actinin and titin turns out to be surprisingly weak if force is applied. Depending on the direction of force application, the unbinding forces can more than triple. Our results suggest a model where multiple ?-actinin/Z-repeat interactions cooperate to ensure long-term stable titin anchoring while allowing the individual components to exchange dynamically.

SUBMITTER: Grison M 

PROVIDER: S-EPMC5293040 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature