Related Experiment Videos
Brush border myosin-I structure and ADP-dependent conformational changes revealed by cryoelectron microscopy and
1Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
The Journal of Cell Biology
|November 14, 1997
Summary
Brush border myosin-I (BBM-I) undergoes a significant ADP-dependent tail swing, revealing its structural dynamics. This research provides insights into the actomyosin ATPase cycle by comparing BBM-I to other myosin types.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Brush border myosin-I (BBM-I) is a single-headed myosin crucial for microvilli structure in intestinal epithelial cells.
- BBM-I connects actin filaments to the plasma membrane, playing a role in cellular organization.
Purpose of the Study:
- To generate high-resolution 3D maps of actin filaments decorated with BBM-I.
- To elucidate the structural changes of BBM-I during the actomyosin ATPase cycle, particularly the ADP-dependent tail swing.
Main Methods:
- Cryoelectron microscopy and helical image analysis were employed to study actin-BBM-I complexes.
- Three-dimensional (3D) maps were generated in the presence and absence of MgADP.
- High-resolution modeling of BBM-I was achieved using crystal structures of myosin catalytic and light chain domains.
Main Results:
- Improved 3D maps revealed the entire light chain-binding domain, including all three calmodulin light chains.
- The ADP-dependent tail swing of BBM-I was measured to be approximately 31 degrees, translating to a 63 Å displacement.
- Structural and energetic differences were observed when comparing BBM-I to skeletal and smooth muscle myosin subfragments-1.
Conclusions:
- The study provides a detailed structural model of BBM-I, enabling direct measurement of its ADP-dependent conformational change.
- Significant differences exist in the actomyosin ATPase cycle energetics and transitions between BBM-I and other myosin classes.