Kinetoplastid membrane protein-11 adopts a four-helix bundle fold in DPC micelle

Abstract

Kinetoplastid membrane protein-11 (KMP11) is a membrane-associated surface protein of kinetoplastids, which has a strong antigenicity but no mammalian homolog, thus representing a promising vaccine candidate. Here, by CD and NMR, we revealed that in buffer, KMP11 assumes a highly helical conformation without stable tertiary packing. Remarkably, upon interacting with dodecylphosphocholine (DPC) micelle, despite minor changes in secondary structures, KMP11 undergoes rearrangements to form a defined structure. We found that its three-dimensional structure unexpectedly adopts the classic four-helix bundle fold. The surface constituted by the N-/C-termini and conserved loop was characterized to dynamically interact with the polar phase of DPC micelle. Our results provide a structural basis for understanding KMP11 functions and further offer a promising avenue for engineering better vaccines. Database: The structure coordinate of KMP11 in DPC micelle has been deposited in PDB with ID of 5Y70 and the associated NMR data were deposited in BMRB with ID of 36112.