SVP-like MADS-box protein from Carya cathayensis forms higher-order complexes

Area of Science:

• Plant Molecular Biology
• Protein Biochemistry
• Genetics

Background:

• MADS-domain transcription factors are crucial for regulating plant flowering time and floral development.
• These factors typically form homo- and hetero-dimers, and hetero-higher-order complexes.
• The capacity of MADS-box proteins to form homo-higher-order complexes remains largely unexplored.

Purpose of the Study:

• To investigate the complex formation of an SVP-like MADS-box protein from hickory.
• To determine if this MADS-box protein can form homo-higher-order complexes.
• To elucidate the structural basis for higher-order complex formation.

Main Methods:

• Biochemical approaches were employed to analyze protein complex formation.
• Yeast two-hybrid (Y2H) assays were used to verify homo-complex formation in vivo.
• Western blotting was performed on hickory floral bud samples to assess native protein complexation.
• Deletion assays were conducted to identify regions responsible for complex formation.

Main Results:

• The SVP-like MADS-box protein forms a heterogeneous higher-order complex, with peak populations exceeding 20 monomers.
• Y2H confirmed the protein's ability to form homo-complexes within yeast cells.
• Western blot analysis revealed the protein exists as higher-order polymers in native hickory floral buds.
• Deletion assays identified flexible C-terminal residues as critical for higher-order polymer formation and heterogeneity.

Conclusions:

• This study provides direct biochemical evidence that an active MADS-box protein can form high-order complexes, significantly larger than previously characterized polymers.
• A subset of MADS-box proteins may self-assemble into extensive complexes, potentially differentiating subfamilies structurally.
• These findings significantly supplement the understanding of MADS-box protein mechanisms in plant development.