Qualitative computational bioanalytics: assembly of viral channel-forming peptides around mono and divalent ions.

A fine-grained docking protocol was used to generate a bundle-like structure of the bitopic membrane protein Vpu from HIV-1. Vpu is a type I membrane protein with 81 amino acids. It is proposed that Vpu forms ion- and substrate-conducting bundles, which are located at the plasma membrane in the infected cell. The Vpu1-32 peptide that includes the transmembrane domain (TMD) is assembled into homo-pentameric bundles around prepositioned Na, K, Ca or Cl ions. For bundles with the lowest energy, the TMDs generate a hydrophobic pore. Bundles in which Ser-24 faces the pore have higher energy. The tilt of the helices in the lowest energy bundles is larger than bundles with serines facing the pore. Left-handed bundles are lowest in energy where the ions are located at the serines.