Structure of a Classical MHC Class I Molecule That Binds “Non-Classical” Ligands

Abstract

The chicken MHC YF1*7.1 X-ray structures reveal that this protein binds lipids and thus represents a "hybrid" class I complex with features of classical as well as non-classical MHC molecules.

Characterization of major histocompatibility complex class I loci of the lark sparrow (Chondestes grammacus) and insights into avian MHC evolution

“…This codon is also missing in some MHC class I sequences recently characterized in the house sparrow (Follin et al 2013;Karlsson and Westerdahl 2013). These studies and our results therefore suggest that MHC class I proteins may have different PBR sites involved in antigen recognition, as demonstrated by the structural analysis of the chicken MHC class I protein (Hee et al 2010). Many of these issues have the potential to be resolved in the future with extensive and detailed characterization of individual species' MHC gene families based on a range of laboratory methods, including whole-genome sequencing (Jarvis et al 2014).…”

“…Exon 3 and introns 2 and 3 were assigned based upon published avian MHC class I sequences. Codons were translated using MEGA 5 (Tamura et al 2011) and assignment of the PBR was based upon inferred passerine PBR sequences (Alcaide et al 2009;Balakrishnan et al 2010;Alcaide et al 2013) on the basis of its homology with the HLA (Björkman et al 1987) and chicken MHC (Kaufman et al 1995;Hee et al 2010). Sequences indicating the presence of at least one stop codon (due to changes in reading frame from indels or nonsense sequences) were classified as pseudogenes.…”

“…Avian species have been found to exhibit a broad range of this diversity and thus provide a very intriguing example of the evolutionary history of the MHC. The MHC of the domestic chicken (Gallus gallus) has been thoroughly characterized over the past few decades (Kaufman et al 1995;Shiina et al 2004Shiina et al , 2007Hee et al 2010). In this species, the MHC is extremely simplified and compact compared to that of other vertebrates.…”

Evolution of nonclassical MHC-dependent invariant T cells

“…To date, MR1 has only been described in mammals. However, the chicken MHC class I-like molecule YF1*7.1 that shares 38% sequence identity with, and is structurally similar to, human MR1, may represent an avian MR1-like gene [41, 48]. Based on these studies, it has been hypothesized that both MR1 and CD1 are phylogenetically old and, possibly via different evolutionary paths, might have evolved from a duplication of the MHC class I locus in a primordial reptilian ancestor.…”

“…The gene encoding MR1 originally described in humans has now been identified in a number of different mammals including non-human primates, rodents, cattle, sheep, and more recently, in placental mammals [38, 66]. An MR1-like gene has also been described in chickens [48]. The mammalian MR1s are monogenic and display between 81-89% sequence identity in the putative peptide binding domains.…”