Oligomerization of neutral peptides derived from the JC virus agnoprotein through a cysteine residue.

The JC virus is the causative agent of progressive multifocal leukoencephalopathy. The viral genome encodes a multifunctional protein known as agnoprotein which is essential for viral proliferation and reported to possess the oligomerization sequence. However, the structural relationship with the oligomerization is unclear. We synthesized 23 amino acid residue neutral peptides derived from the JC virus agnoprotein, Lys22 to Asp44. The secondary structures of these peptides were β-sheet in aqueous buffer that converted to a helical structure in a hydrophobic environment. These peptides interestingly formed dimers and oligomers under oxidizing conditions. The oligomerization was facilitated by addition of bismaleimides and the derivative without thiol group did not form such oligomers. These results suggest that Agno(22-44) could be transmembrane and one disulfide bond between Cys40 triggers the oligomerization.