Comprehensive analysis of HAMP domains: implications for transmembrane signal transduction

Area of Science:

• Molecular biology
• Biophysics
• Structural biology

Background:

• Homodimeric receptors with transmembrane segments are vital cellular components.
• The signaling mechanism of these receptors, particularly the HAMP domain, remains debated.
• A proposed model involves axial helix rotation for signal transduction.

Purpose of the Study:

• To statistically validate a new model of transmembrane receptor signaling via axial helix rotation.
• To identify coevolving residue networks within the HAMP domain that facilitate signal transduction.
• To classify HAMP domains and understand their specificity in histidine kinases and chemoreceptors.

Main Methods:

• Statistical analysis of HAMP domain sequences.
• Sequence clustering for classification.
• Analysis of coevolving residue networks.

Main Results:

• HAMP domain sequences exhibit biophysical properties supporting two proposed conformations for axial helix rotation.
• Three coevolving residue networks were identified, detailing the steps of the signaling mechanism.
• HAMP domains show specificity for either histidine kinases or chemoreceptors, with distinct coevolutionary patterns.
• Membrane-bound HAMP domains form a central supercluster, receiving input from transmembrane helices.

Conclusions:

• The axial helix rotation model provides a framework for understanding HAMP domain-mediated signaling.
• Coevolutionary networks highlight the stepwise nature of signal transduction and domain specificity.
• HAMP domain specificity for histidine kinases or chemoreceptors is largely maintained, influencing protein recombination capabilities.