Chapter category: Development
3D Structure of Myosin Crossbridges in Insect Flight Muscle: Toward Visualization of the Conformations During Myosin Motor Action
Nature's Versatile Engine: Insect Flight Muscle Inside and Out
Edited by: Jim O. VigoreauxISBN: 0-387-25798-5
» Get more information about this book at landesbioscience.com «
Chapter authors:
Mary C. Reedy
Insect flight muscle (IFM) provides a model system that allows direct viewing of individual myosin head structures in situ that give rise to the average structures reported by X-ray patterns and by the mechanical behavior of the fibers. Coordinating x-ray diffraction, physiological monitoring and fast freezing with EM tomography, correspondence class averaging and atomic model building in IFM is providing 3D imaging of different myosin conformations in situ in relaxed, active and rigor states. Rigor has yielded the most detailed 3D structure, showing actin, myosin S2 and a distribution of variously flexed myosin lever arm in class averages. EM tomograms of fast frozen/freeze substituted isometric and stretch-activated contractions show that crossbridges in active contraction bind to actin target zones by only one head, in contrast to the most prominent class of rigor crossbridges that attach with both myosin heads to actin. In contrast to a ~5nm lever arm swing inferred during rigor induction, active myosin heads display a wide range of crossbridge angles, consistent with a power stroke greater than 10nm, that proceeds from a prestroke “up” configuration “down” to a rigor angle. However, measurements of isometrically active IFM crossbridges to determine their position, angle and frequency of attachment to actin indicate that the majority of crossbridges in isometric contraction are angled close to perpendicular to the filament axis (60% within 11o), results that are consistent with X-ray studies of vertebrate isometric contraction. X-ray modeling of ATP relaxed Lethocerus IFM shows that a myosin head conformation similar to “prestroke” crystal structures, is arrayed in the 14.5nm periodic “shelves” along thick filaments such that only one head of each molecule is well-positioned, as if poised to bind to actin upon activation, while the other head curves around the thick filament shaft.
Additional chapters from this book:
Insect Flight Muscle Chemomechanics
David Maughan and Douglas Swank
The biochemical and mechanical basis of insect flight has captivated the interest of biologists for decades. This chapter presents a brief review of the approaches used and results obtained by inves...
Troponin, Tropomyosin and GST-2
Alberto Ferrus
Troponin, Tropomyosin and GST are generic names of protein families that play a variety of cellular roles in the biology of uni- and multicellular organisms. In muscles, specific family members are ...
A Naturalist’s View of Insect Flight Muscle
Bernd Heinrich
By almost any measure, insects as a group are an astounding evolutionary achievement. Through their diversity and their adaptation to a great range of life-styles, forms, and physical and biological...
Structure of The Insect Thick Filaments
Gernot Beinbrech and Gereon Ader
Myosin filaments of insect indirect flight muscles (IFM) are 17 to 19 nm thick and 1.9 to 3.6 µm long structures with probably 4 cross-bridges per level (=crown). These crowns repeat in periods of 1...
Insect Flight Muscle Chemomechanics
David Maughan and Douglas Swank
The biochemical and mechanical basis of insect flight has captivated the interest of biologists for decades. This chapter presents a brief review of the approaches used and results obtained by inves...
3D Structure of Myosin Crossbridges in Insect Flight Muscle: Toward Visualization of the Conformations During Myosin Motor Action
Mary C. Reedy
Insect flight muscle (IFM) provides a model system that allows direct viewing of individual myosin head structures in situ that give rise to the average structures reported by X-ray patterns and by ...
The Contributions of Genetics to the Study of Insect Flight Muscle Function
Richard M. Cripps
The utility of Drosophila as a model genetic organism has had a profound impact upon our understanding of muscle assembly and function. This has arisen from the large number of mutant alleles that h...
Actin and Arthrin
John C. Sparrow
Filamentous actin forms the core of all muscle thin filaments and is an integral part of the acto-myosin motor system that powers muscle contraction. Muscle actin isoforms show considerable sequence...
X-Ray Diffraction of Indirect Flight Muscle from Drosophila in Vivo
Thomas C. Irving
The indirect flight muscle (IFM) of the fruit fly, Drosophila, represents a powerful model system for integrated structure and function studies because of the ease of genetically manipulating this o...
Molecular Assays for Acto-myosin Interactions
John C. Sparrow and Michael A. Geeves
The indirect flight muscles of insects are highly specialised to produce power for flight. Asynchronous flight muscle contraction is largely isometric (3-4% shortening in vivo) and can occur at high...
Stretch Activation: Toward a Molecular Mechanism
Jeffrey R. Moore
Insect flight is often powered by high wing beat frequencies. Surprisingly, the flight muscles of some insects are capable of driving high wing beats without extensive calcium cycling machinery. Rat...
Mapping Myofibrillar Protein Interactions by Mutational Proteomics
Joshua A. Henkin and Jim O. Vigoreaux
The myofibril is a multiprotein complex that performs the contractile activity of the muscle cell. Biochemical experiments over the past decades have revealed protein interactions that are critical ...
Sustained High Power Performance: Possible Strategies for Integrating Energy Supply and Demand in Flight Muscle
Vivek Vishnudas and Jim O. Vigoreaux
The high power output necessary for insect flight has resulted in the evolution of muscles with large and abundant myofibrils, the so called ‘myofibrillar’ muscles. In principle, this modification s...
Novel Myosin Associated Proteins
Byron Barton and Jim O. Vigoreaux
Asynchronous insect flight muscle (IFM) relies on high frequency operation to achieve higher power output than a comparable synchronous muscle. The biochemical, ultra structural, and mechanical adap...
The Thin Filament in Insect Flight Muscle
Kevin R. Leonard and Belinda Bullard
In this chapter we describe the special properties of insect muscle thin filament proteins and the way in which they differ from those in vertebrates. As in the vertebrate, the repeating unit of the...
The Insect Z-band
Judith D. Saide
The Z-band is an electron dense structure that borders sarcomeres in striated muscle. It is a complex assembly of proteins that organizes and stabilizes both thick and thin filament arrays in the co...
Myosin
Becky M. Miller and Sanford I. Bernstein
The molecular motor myosin, composed of two heavy chains and four light chains, is responsible for defining both structural and mechanical properties of insect flight muscle. Myosin polymerizes into...
Paramyosin and Miniparamyosin
Margarita Cervera, Juan Jose Arredondo and Raquel Marco Ferreres
In Drosophila, paramyosin and miniparamyosin are structural components of thick filaments that have a similar structure to the myosin heavy chain rod tail. Both proteins are rod-like molecules with ...
Comparative Physiology of Insect Flight Muscle
Robert K. Josephson
Insect flight is powered by muscles that attach more-or-less directly to the wings (direct flight muscles) and muscles that bring about wing movement by distorting the insect’s thorax (indirect flig...
Functional and Ecological Effects of Isoform Variation in Insect Flight Muscle
James H. Marden
Nearly all of the known structural molecules in insect flight muscles exist as multiple isoforms. Both post-transcriptional and post-translational mechanisms are responsible for this variability. Am...
Some Functions of Proteins from the Drosophila Sallimus (sls) Gene
Belinda Bullard, Mark C. Leake and Kevin Leonard
Insect flight muscles contract at high frequencies and are activated by periodically stretching the muscles. For the stretch to have an effect, the muscles must be stiff. Two elastic proteins, proje...
Muscle Systems Design and Integration
Fritz-Olaf Lehmann
The recent advances in experimental technology allows us to assess the mechanical power output and function of the Drosophila flight muscle within the context of the flying animal. In an intact anim...
Projectin the Elastic Protein of the C-filaments
Agnes Ayme-Southgate and Richard Southgate
In adult insects, the highly specialized indirect flight muscles (abbreviated as IFMs) are powerful muscles adapted for the rapid repeated contractions necessary for flight. These muscles are referr...
