Protein interaction evolution from promiscuity to specificity with reduced flexibility in an increasingly complex...

Area of Science:

• Evolutionary biology
• Molecular biology
• Systems biology

Background:

• Understanding protein evolution and its impact on protein interaction networks is crucial.
• MADS-domain transcription factors play key roles in plant development and evolution.
• SEPALLATA3 is a hub protein involved in network organization.

Purpose of the Study:

• To investigate the evolution of SEPALLATA3, a plant MADS-domain transcription factor.
• To understand how SEPALLATA3's evolution influenced its role in protein interaction networks.
• To explore the mechanisms driving protein interaction evolution.

Main Methods:

• Utilized extant and resurrected ancestral plant MADS-domain transcription factors.
• Employed network analysis to study protein interactions.
• Performed domain-swapping experiments between networks of different ages.

Main Results:

• SEPALLATA3 evolved increased interaction specificity and reduced conformational flexibility, partly due to proline accumulation.
• Despite a saturated dimeric interaction network, SEPALLATA3 mediated new interactions post-genome triplication.
• SHORT VEGETATIVE PHASE gained interactions via C-terminal domain insertion, expanding its interface.

Conclusions:

• Protein interaction evolution is driven by changes in conformational dynamics, influenced by binding mechanisms like induced fit or conformational selection.
• Proteins can evolve towards greater specificity and reduced flexibility to meet the demands of complex interaction networks.
• Evolutionary adaptations in proteins like SEPALLATA3 are critical for shaping the architecture of cellular networks.