title: Genomic donor cassette sharing during VLRA and VLRC assembly in jawless vertebrates.
abstract: Lampreys possess two T-like lymphocyte lineages that express either variable lymphocyte receptor (VLR) A or VLRC antigen receptors. VLRA(+) and VLRC(+) lymphocytes share many similarities with the two principal T-cell lineages of jawed vertebrates expressing the αβ and γδ T-cell receptors (TCRs). During the assembly of VLR genes, several types of genomic cassettes are inserted, in step-wise fashion, into incomplete germ-line genes to generate the mature forms of antigen receptor genes. Unexpectedly, the structurally variable components of VLRA and VLRC receptors often possess partially identical sequences; this phenomenon of module sharing between these two VLR isotypes occurs in both lampreys and hagfishes. By contrast, VLRA and VLRC molecules typically do not share their building blocks with the structurally analogous VLRB receptors that are expressed by B-like lymphocytes. Our studies reveal that VLRA and VLRC germ-line genes are situated in close proximity to each other in the lamprey genome and indicate the interspersed arrangement of isotype-specific and shared genomic donor cassettes; these features may facilitate the shared cassette use. The genomic structure of the VLRA/VLRC locus in lampreys is reminiscent of the interspersed nature of the TCRA/TCRD locus in jawed vertebrates that also allows the sharing of some variable gene segments during the recombinatorial assembly of TCR genes.
authors.affiliation: Emory Vaccine Center and Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322;
authors.forename: Sabyasachi
authors.initials: S
authors.lastname: Das
authors.affiliation: Emory Vaccine Center and Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322;
authors.forename: Jianxu
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Developmental Immunology, Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; and.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Holland
authors.affiliation: National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894.
authors.forename: Lakshminarayan M
authors.initials: LM
authors.lastname: Iyer
authors.affiliation: Emory Vaccine Center and Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322;
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hirano
authors.affiliation: Department of Developmental Immunology, Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; and.
authors.forename: Michael
authors.initials: M
authors.lastname: Schorpp
authors.affiliation: National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894.
authors.forename: L
authors.initials: L
authors.lastname: Aravind
authors.affiliation: Emory Vaccine Center and Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322; mdcoope@emory.edu boehm@immunbio.mpg.de.
authors.forename: Max D
authors.initials: MD
authors.lastname: Cooper
authors.affiliation: Department of Developmental Immunology, Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; and mdcoope@emory.edu boehm@immunbio.mpg.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Boehm
mesh_terms: D000818:Animals; D001483:Base Sequence; D019143:Evolution, Molecular; D056426:Genetic Loci; D016678:Genome / Q000235:genetics*; D006196:Hagfishes / Q000235:genetics / Q000276:immunology; D007568:Jaw / Q000033:anatomy & histology*; D007798:Lampreys / Q000235:genetics / Q000276:immunology; D008969:Molecular Sequence Data; D011946:Receptors, Antigen / Q000235:genetics* / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D014714:Vertebrates / Q000235:genetics* / Q000276:immunology*
chemical_list: D011946:Receptors, Antigen
keywords: adaptive immunity; agnatha; molecular evolution; selection