Calponin-like Chd64 is partly disordered.

Area of Science:

• Insect molecular biology
• Developmental endocrinology
• Protein structural biology

Background:

• Insect development is regulated by complex interactions between 20-hydroxyecdysone (20E) and juvenile hormone (JH) signaling pathways.
• Chd64 and FKBP39 proteins are known to be involved in the cross-talk between 20E and JH, but the molecular mechanisms are unclear.

Purpose of the Study:

• To investigate the structural features of Chd64 proteins from Drosophila melanogaster and Tribolium castaneum.
• To understand the role of Chd64's structure in mediating the interaction between 20E and JH signaling pathways.

Main Methods:

• In silico computational analysis of protein structure.
• In vitro biophysical techniques including analytical size-exclusion chromatography, analytical ultracentrifugation, and small-angle X-ray scattering (SAXS).

Main Results:

• Computational analysis predicted disordered regions at the termini and a globular central calponin homology (CH) domain for both DmChd64 and TcChd64.
• Hydrodynamic analyses revealed an asymmetrical, elongated shape for both proteins.
• SAXS and Kratky plot analyses confirmed protein disorderness, likely at the termini, influencing hydrodynamic properties.

Conclusions:

• Chd64 proteins possess intrinsically disordered regions (IDRs) at their termini.
• These IDRs likely serve as platforms for multiple interactions, forming the basis of Chd64's regulatory function in linking 20E and JH signaling pathways.