title: Reconstructing an ancestral mammalian immune supercomplex from a marsupial major histocompatibility complex.
abstract: The first sequenced marsupial genome promises to reveal unparalleled insights into mammalian evolution. We have used the Monodelphis domestica (gray short-tailed opossum) sequence to construct the first map of a marsupial major histocompatibility complex (MHC). The MHC is the most gene-dense region of the mammalian genome and is critical to immunity and reproductive success. The marsupial MHC bridges the phylogenetic gap between the complex MHC of eutherian mammals and the minimal essential MHC of birds. Here we show that the opossum MHC is gene dense and complex, as in humans, but shares more organizational features with non-mammals. The Class I genes have amplified within the Class II region, resulting in a unique Class I/II region. We present a model of the organization of the MHC in ancestral mammals and its elaboration during mammalian evolution. The opossum genome, together with other extant genomes, reveals the existence of an ancestral "immune supercomplex" that contained genes of both types of natural killer receptors together with antigen processing genes and MHC genes.
authors.affiliation: Centre for Advanced Technologies in Animal Genetics and Reproduction, Faculty of Veterinary Science, The University of Sydney, Camden, Australia. kbelov@camden.usyd.edu.au
authors.forename: Katherine
authors.initials: K
authors.lastname: Belov
authors.forename: Janine E
authors.initials: JE
authors.lastname: Deakin
authors.forename: Anthony T
authors.initials: AT
authors.lastname: Papenfuss
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Baker
authors.forename: Sandra D
authors.initials: SD
authors.lastname: Melman
authors.forename: Hannah V
authors.initials: HV
authors.lastname: Siddle
authors.forename: Nicolas
authors.initials: N
authors.lastname: Gouin
authors.forename: David L
authors.initials: DL
authors.lastname: Goode
authors.forename: Tobias J
authors.initials: TJ
authors.lastname: Sargeant
authors.forename: Mark D
authors.initials: MD
authors.lastname: Robinson
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Wakefield
authors.forename: Shaun
authors.initials: S
authors.lastname: Mahony
authors.forename: Joseph G R
authors.initials: JG
authors.lastname: Cross
authors.forename: Panayiotis V
authors.initials: PV
authors.lastname: Benos
authors.forename: Paul B
authors.initials: PB
authors.lastname: Samollow
authors.forename: Terence P
authors.initials: TP
authors.lastname: Speed
authors.forename: Jennifer A Marshall
authors.initials: JA
authors.lastname: Graves
authors.forename: Robert D
authors.initials: RD
authors.lastname: Miller
mesh_terms: D000818:Animals; D002875:Chromosomes / Q000235:genetics; D019143:Evolution, Molecular; D015870:Gene Expression / Q000235:genetics; D006801:Humans; D017403:In Situ Hybridization; D008285:Major Histocompatibility Complex / Q000235:genetics* / Q000276:immunology*; D008394:Marsupialia / Q000235:genetics* / Q000276:immunology*; D008677:Metaphase; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D012333:RNA, Messenger