Next Article in Journal
CaWRKY40b in Pepper Acts as a Negative Regulator in Response to Ralstonia solanacearum by Directly Modulating Defense Genes Including CaWRKY40
Next Article in Special Issue
Temperature Effects on Force and Actin–Myosin Interaction in Muscle: A Look Back on Some Experimental Findings
Previous Article in Journal
Functional Analysis of the Promoter Region of Japanese Flounder (Paralichthys olivaceus) β-actin Gene: A Useful Tool for Gene Research in Marine Fish
Previous Article in Special Issue
Electron Microscopic Recording of the Power and Recovery Strokes of Individual Myosin Heads Coupled with ATP Hydrolysis: Facts and Implications
Open AccessReview

Unconventional Imaging Methods to Capture Transient Structures during Actomyosin Interaction

1
Waseda Research Institute for Science and Engineering, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
2
WPI Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
3
Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
*
Author to whom correspondence should be addressed.
Int. J. Mol. Sci. 2018, 19(5), 1402; https://doi.org/10.3390/ijms19051402
Received: 17 April 2018 / Revised: 4 May 2018 / Accepted: 5 May 2018 / Published: 8 May 2018
(This article belongs to the Special Issue The Actin-Myosin Interaction in Muscle)
Half a century has passed since the cross-bridge structure was recognized as the molecular machine that generates muscle tension. Despite various approaches by a number of scientists, information on the structural changes in the myosin heads, particularly its transient configurations, remains scant even now, in part because of their small size and rapid stochastic movements during the power stroke. Though progress in cryo-electron microscopy is eagerly awaited as the ultimate means to elucidate structural details, the introduction of some unconventional methods that provide high-contrast raw images of the target protein assemblies is quite useful, if available, to break the current impasse. Quick-freeze deep–etch–replica electron microscopy coupled with dedicated image analysis procedures, and high-speed atomic-force microscopy are two such candidates. We have applied the former to visualize actin-associated myosin heads under in vitro motility assay conditions, and found that they take novel configurations similar to the SH1–SH2-crosslinked myosin that we characterized recently. By incorporating biochemical and biophysical results, we have revised the cross-bridge mechanism to involve the new conformer as an important main player. The latter “microscopy” is unique and advantageous enabling continuous observation of various protein assemblies as they function. Direct observation of myosin-V’s movement along actin filaments revealed several unexpected behaviors such as foot-stomping of the leading head and unwinding of the coiled-coil tail. The potential contribution of these methods with intermediate spatial resolution is discussed. View Full-Text
Keywords: myosin cross-bridges; myosin-II; myosin-V; actin; quick-freeze deep-etch replica electron microscopy; cryo-electron microscopy; high-speed atomic-force microscopy; structural intermediate; lever-arm swinging; myosin subdomains myosin cross-bridges; myosin-II; myosin-V; actin; quick-freeze deep-etch replica electron microscopy; cryo-electron microscopy; high-speed atomic-force microscopy; structural intermediate; lever-arm swinging; myosin subdomains
Show Figures

Graphical abstract

MDPI and ACS Style

Katayama, E.; Kodera, N. Unconventional Imaging Methods to Capture Transient Structures during Actomyosin Interaction. Int. J. Mol. Sci. 2018, 19, 1402.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop