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Data for: MHC I of the great reed warbler promotes a flat peptide binding mode

Venskutonytė, Raminta1; Kjellström, Sven1; O'Connor, Emily1; Westerdahl, Helena1; Lindkvist-Petersson, Karin1

Research facility: Swedish Research Council
Published Jul 07, 2025 on Dryad. https://doi.org/10.5061/dryad.cvdncjtg1

Data files

Jul 07, 2025 version files 16.72 MB

Abstract

The major histocompatibility complex (MHC) plays a key role in pathogen recognition as part of the adaptive immune system. MHC I gene copy numbers in birds of the order Passeriformes (songbirds) are substantially larger compared to other birds. MHC I diversity and antigen presentation have been carefully characterized in chicken Gallus gallus of the order Galliformes; chickens express few MHC I genes and often present antigens that bulge out of the peptide binding cleft. This observation raises the question whether MHC I present antigens in a similar way in species with many MHC genes? Here, we present the X-ray structure of MHC I from the great reed warbler Acrocephalus arundinaceus (Acar3) a long-distance migratory songbird. Structural analysis shows that MHC I bind the antigen in a flat conformation due to a sequentially well-conserved restriction point, acting like a pair of tweezers, within the peptide binding grove, created by Arg97 and Arg155. This more stringent antigen presentation by Acar MHC I molecules may partly explain the high MHC gene copy numbers seen in the great reed warbler.