TITLE:
Single-Chain Expression and Crystallization of an Antigenic C-Terminus in Complex with the Regulatory Domain of ER Aminopeptidase 1
AUTHORS:
Lufei Sui, Amit Gandhi, Hwai-Chen Guo
KEYWORDS:
Endoplasmic Reticulum Aminopeptidase 1 (ERAP1), ERAP1 Regulatory Domain, Antigen Presentation, X-Ray Crystallography
JOURNAL NAME:
Crystal Structure Theory and Applications,
Vol.4 No.4,
November
24,
2015
ABSTRACT: Human endoplasmic
reticulum aminopeptidase 1 (ERAP1) is one of two ER luminal aminopeptidases
that participate in the final processing of peptide precursors and generates
the N-termini of the MHC class I-restricted epitopes. In order to investigate
the interactions of its binding site with substrate peptides, X-ray
crystallographic analyses have been carried out to study structures of ERAP1
regulatory (ERAP1_R) domain in complex with antigenic peptides. Single-chain
bimodular constructs with various antigenic peptides linked to the C-terminal
end of ERAP1_R domain are designed to facilitate crystallization process of
these complexes. These recombinant proteins have been purified and crystalized,
and x-ray diffraction data of one crystal have been processed to a resolution
of 2.8 . The crystal belongs to the space group P21, with unit cell
parameters a =64.2, b = 66.8, c = 66.3 , β = 110.2°. A Refmac-refined omit map reveals a clear density for the
antigenic peptide’s carboxylate-end that is in contact with the ERAP1
regulatory domain of neighboring molecule. Thus the single-chain bimodular
constructs have provided an expedited approach to study sequence-specific
interactions between the ERAP1 regulatory domain and antigen peptide’s
C-terminal ends.