Molecular recognition in dimerization between PB1 domains

Area of Science:

• Molecular biology
• Protein-protein interactions
• Structural biology

Background:

• The Phox and Bem 1 (PB1) domain is a protein module mediating heterodimeric complex formation.
• PB1 domains contain a conserved lysine residue and an acidic OPCA motif, crucial for electrostatic interactions.
• Previous studies identified PB1 complexes in phagocyte oxidase activators and yeast polarity proteins.

Purpose of the Study:

• To investigate molecular recognition mechanisms of PB1 domains.
• To understand interactions mediated by proteins with both lysine and OPCA motifs within a single PB1 domain.
• To explore the binding versatility of Par6, atypical protein kinase C (aPKC), and ZIP proteins.

Main Methods:

• Investigated protein-protein interactions involving PB1 domains.
• Analyzed binding interfaces using electrostatic interaction principles.
• Examined complex formation in proteins like Par6, aPKC, and ZIP.

Main Results:

• Par6 and aPKC form a complex via Par6 lysine and aPKC-OPCA, localizing to epithelial cell tight junctions.
• aPKC's OPCA interacts with ZIP's PB1 domain, while aPKC's lysine binds MEK5.
• ZIP forms homotypic complexes through electrostatic interactions, showcasing PB1 domain versatility.

Conclusions:

• PB1 domains utilize both lysine and OPCA motifs for molecular recognition.
• These domains exhibit a broad repertoire of protein-protein interactions.
• The study elucidates the complex binding strategies of PB1 domains in various cellular contexts.