Six amino acids define a minimal dimerization sequence and stabilize a transmembrane helix dimer by close packing and hydrogen bonding

• Cytochrome b559′ formation is mainly driven by six amino acids.
• All amino acids are directly involved in helix–helix contact.
• Residues form a paired surface.
• Complex interactions stabilize the TM helix dimer.
• Close packing and hydrogen bonding stabilizes the dimer.

Distinct amino acid sequences have been described to mediate oligomerization of transmembrane α-helices. However, as the sequence context is crucial to determine specificity in transmembrane helix–helix interaction, the question arises how small a sequence can be without losing specificity. In the present analysis, six amino acids have been identified in the PsbF transmembrane helix dimer, which form the contact region of two interacting helices and are directly involved in helix–helix interactions. However, individual amino acids within the complex sequence pattern only together ensure sequence specificity of the analyzed transmembrane helix–helix interactions by mediating close packing and inter-helical hydrogen bonding.

Structured summary of protein interactionspsbF and psbFphysically interact by lex-a dimerization assay (View Interaction: 1, 2, 3, 4, 5)