WYR domain of flightin and myosin

Arya Sukumar, College of Agriculture, Vellayani

The cyclic interaction between myosin and actin gives striated muscle its force-generating characteristics. The indirect flying muscles (IFM) of Drosophila are developed for rapid oscillatory movements. The correlation between the WYR domain of flightin and myosin was delineated by researchers at the University of Vermont, who discovered the ultrastructural regulation capable of finding the molecular structure-function relationship that is critical for muscle mechanical characteristics and structural stability. 

What is protein flightin?

Flightin is a multi-phosphorylated 20-kD myofibrillar protein found in the indirect flight muscles of drosophila (IFM). This novel protein is only discovered in flight muscles so that it has been given the name ‘flightin’. Flightin is needed for myosin formation and sarcomere stability in Drosophila flight muscles. WYR is a conserved protein domain found in the muscle protein flightin that is thought to have evolved 500 million years ago in the ancestor of hexapods and crustaceans. The secondary structure of the WYR domain found in the muscle protein indicates that it binds the coiled-coil motif of muscle myosin and alters its structural characteristics. Characterizing WYR and finding its role in combination with myosin sheds light on the long-term evolutionary mechanisms that drive the Insect’s success. The connection between WYR and myosin also provides a method of ultra-structural control capable of informing the molecular structure-function interactions that are important for muscle mechanical characteristics and structural stability. The insect indirect flight muscle (IFM) is well-ordered, stretchable and capable of producing 1000-beat-per-second wing beats. The Drosophila melanogaster IFM has been used to investigate the molecular underpinnings of muscle and heart function, as well as structure-function connections of myofibrillar proteins and mechanical factors regulated for stretch activation. Flightin mutations in D. melanogaster were studied and it was discovered that it plays an important role in flight and courtship, two activities that highlight insects’ diversification. Similar to the flightin null mutant, mutants who express a shortened flightin lacking the C-terminal region are unable to generate a courtship song or a wing beat to accelerate flight. Mutants that express a shortened flightin that lacks the N-terminal region have poor flight mechanics and produce an aberrant courtship song, which reduces the male’s mating success. Regardless of prior exposure to mechanical activation, muscle fibres in mutants lacking flightin bunch together when subjected to rigour. Drosophila IFM has also been used to find and characterise new contractile proteins that are required to fine-tune the structural characteristics of contractile proteins in order to maximise function. 

According to these findings, flightin is implicated in different alterations in Light-meromyosin (LMM) secondary structure via the WYR domain, which might impact structural characteristics and stability of the thick filament, scaling to the regulation of entire muscle function. These features point to a role for flightin in regulating contraction, through modulation of the actin-myosin interaction. The isolation of mutants with mutations in the flightin gene helps the researchers in scrutinizing this unique flight muscle protein.

Also read: Plug-in Processes for Lignin valorization

Reference

Menard, L., 2021. Structural Characterization of the Novel Flightin Domain Wyr and Its Defining Role in the Thick Filament Structure and Mechanics. The University of Vermont and State Agricultural College.https://scholarworks.uvm.edu/graddis/1341/

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