title: Effects of polymorphic variation on the mechanism of Endoplasmic Reticulum Aminopeptidase 1.
abstract: Endoplasmic Reticulum Aminopeptidase 1 (ERAP1) generates antigenic peptides for loading onto Major Histocompatibility Class I molecules (MHCI) and can regulate adaptive immune responses. During the last few years, many genetic studies have revealed strong associations between coding Single Nucleotide Polymorphisms (SNPs) in ERAP1 and common human diseases ranging from viral infections to cancer and autoimmunity. Functional studies have established that these SNPs affect enzyme activity resulting to changes in antigenic peptide processing, presentation by MHCI and cellular cytotoxic responses. These disease-associated polymorphisms are, however, located away from the enzyme's active site and are interspersed to different structural domains. As a result, the mechanism by which these SNPs can affect function remains largely elusive. ERAP1 utilizes a complex catalytic mechanism that involves a large conformational change between inactive and active forms and has the unique property to trim larger peptides more efficiently than smaller ones. We analyzed two of the most consistently discovered disease-associated polymorphisms, namely K528R and Q730E, for their effect on the ability of the enzyme to select substrates based on length and to undergo conformational changes. By utilizing enzymatic and computational analysis we propose that disease-associated SNPs can affect ERAP1 function by influencing: (i) substrate length selection and (ii) the conformational distribution of the protein ensemble. Our results provide novel insight on the mechanisms by which polymorphic variation distal from the active site of ERAP1 can translate to changes in function and contribute to immune system variability in humans.
authors.affiliation: National Center for Scientific Research Demokritos, Agia Paraskevi, Athens 15310, Greece.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Stamogiannos
authors.affiliation: National Center for Scientific Research Demokritos, Agia Paraskevi, Athens 15310, Greece.
authors.forename: Despoina
authors.initials: D
authors.lastname: Koumantou
authors.affiliation: National Center for Scientific Research Demokritos, Agia Paraskevi, Athens 15310, Greece. Electronic address: thpap@rrp.demokritos.gr.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Papakyriakou
authors.affiliation: National Center for Scientific Research Demokritos, Agia Paraskevi, Athens 15310, Greece. Electronic address: stratos@rrp.demokritos.gr.
authors.forename: Efstratios
authors.initials: E
authors.lastname: Stratikos
mesh_terms: D000626:Aminopeptidases / Q000737:chemistry / Q000235:genetics*; D018360:Crystallography, X-Ray; D004591:Electrophoresis, Polyacrylamide Gel; D005453:Fluorescence; D006801:Humans; D007931:Leucyl Aminopeptidase / Q000378:metabolism; D015778:Minor Histocompatibility Antigens; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D010455:Peptides / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D025341:Principal Component Analysis; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity
chemical_list: D015778:Minor Histocompatibility Antigens; D010455:Peptides; D000626:Aminopeptidases; C464841:ERAP1 protein, human; D007931:Leucyl Aminopeptidase
keywords: Accelerated molecular dynamics; Aminopeptidase; Antigen epitopes; Antigen processing; Peptides; Principle component analysis; Single nucleotide polymorphisms (SNPs)