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.