Cryo-electron tomography of cardiac myofibrils reveals a 3D lattice spring within the Z-discs.
Commun Biol
; 3(1): 585, 2020 10 16.
Article
em En
| MEDLINE
| ID: mdl-33067529
ABSTRACT
The Z-disc forms a boundary between sarcomeres, which constitute structural and functional units of striated muscle tissue. Actin filaments from adjacent sarcomeres are cross-bridged by α-actinin in the Z-disc, allowing transmission of tension across the myofibril. Despite decades of studies, the 3D structure of Z-disc has remained elusive due to the limited resolution of conventional electron microscopy. Here, we observed porcine cardiac myofibrils using cryo-electron tomography and reconstructed the 3D structures of the actin-actinin cross-bridging complexes within the Z-discs in relaxed and activated states. We found that the α-actinin dimers showed contraction-dependent swinging and sliding motions in response to a global twist in the F-actin lattice. Our observation suggests that the actin-actinin complex constitutes a molecular lattice spring, which maintains the integrity of the Z-disc during the muscle contraction cycle.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Tomografia com Microscopia Eletrônica
/
Miocárdio
/
Miofibrilas
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article