title: A new, expressed multigene family containing a hot spot for insertion of retroelements is associated with polymorphic subtelomeric regions of Trypanosoma brucei.
abstract: We describe a novel gene family that forms clusters in subtelomeric regions of Trypanosoma brucei chromosomes and partially accounts for the observed clustering of retrotransposons. The ingi and ribosomal inserted mobile element (RIME) non-LTR retrotransposons share 250 bp at both extremities and are the most abundant putatively mobile elements, with about 500 copies per haploid genome. From cDNA clones and subsequently in the T. brucei genomic DNA databases, we identified 52 homologous gene and pseudogene sequences, 16 of which contain a RIME and/or ingi retrotransposon inserted at exactly the same relative position. Here these genes are called the RHS family, for retrotransposon hot spot. Comparison of the protein sequences encoded by RHS genes (21 copies) and pseudogenes (24 copies) revealed a conserved central region containing an ATP/GTP-binding motif and the RIME/ingi insertion site. The RHS proteins share between 13 and 96% identity, and six subfamilies, RHS1 to RHS6, can be defined on the basis of their divergent C-terminal domains. Immunofluorescence and Western blot analyses using RHS subfamily-specific immune sera show that RHS proteins are constitutively expressed and occur mainly in the nucleus. Analysis of Genome Survey Sequence databases indicated that the Trypanosoma brucei diploid genome contains about 280 RHS (pseudo)genes. Among the 52 identified RHS (pseudo)genes, 48 copies are in three RHS clusters located in subtelomeric regions of chromosomes Ia and II and adjacent to the active bloodstream form expression site in T. brucei strain TREU927/4 GUTat10.1. RHS genes comprise the remaining sequence of the size-polymorphic "repetitive region" described for T. brucei chromosome I, and a homologous gene family is present in the Trypanosoma cruzi genome.
authors.affiliation: Laboratoire de Parasitologie Moléculaire, Université Victor Segalen Bordeaux II, UMR-5016 CNRS, 33076 Bordeaux, France. bringaud@u-bordeaux2.fr
authors.forename: Frederic
authors.initials: F
authors.lastname: Bringaud
authors.forename: Nicolas
authors.initials: N
authors.lastname: Biteau
authors.forename: Sara E
authors.initials: SE
authors.lastname: Melville
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Hez
authors.forename: Najib M
authors.initials: NM
authors.lastname: El-Sayed
authors.forename: Vanessa
authors.initials: V
authors.lastname: Leech
authors.forename: Matthew
authors.initials: M
authors.lastname: Berriman
authors.forename: Neil
authors.initials: N
authors.lastname: Hall
authors.forename: John E
authors.initials: JE
authors.lastname: Donelson
authors.forename: Théo
authors.initials: T
authors.lastname: Baltz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D017125:Genes, Protozoan; D008969:Molecular Sequence Data; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D010802:Phylogeny; D011110:Polymorphism, Genetic; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics; D011544:Pseudogenes; D018626:Retroelements; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D016615:Telomere / Q000235:genetics; D014346:Trypanosoma brucei brucei / Q000145:classification / Q000235:genetics*; D014349:Trypanosoma cruzi / Q000235:genetics
chemical_list: D017931:DNA Primers; D016054:DNA, Protozoan; D015800:Protozoan Proteins; C469912:RHS1a protein, Trypanosoma brucei; D018626:Retroelements