title: Sequence and analysis of chromosome I of the amitochondriate intracellular parasite Encephalitozoon cuniculi (Microspora).
abstract: A DNA sequencing program was applied to the small (<3 Mb) genome of the microsporidian Encephalitozoon cuniculi, an amitochondriate eukaryotic parasite of mammals, and the sequence of the smallest chromosome was determined. The approximately 224-kb E. cuniculi chromosome I exhibits a dyad symmetry characterized by two identical 37-kb subtelomeric regions which are divergently oriented and extend just downstream of the inverted copies of an 8-kb duplicated cluster of six genes. Each subtelomeric region comprises a single 16S-23S rDNA transcription unit, flanked by various tandemly repeated sequences, and ends with approximately 1 kb of heterogeneous telomeric repeats. The central (or core) region of the chromosome harbors a highly compact arrangement of 132 potential protein-coding genes plus two tRNA genes (one gene per 1.14 kb). Most genes occur as single copies with no identified introns. Of these putative genes, only 53 could be assigned to known functions. A number of genes from the transcription and translation machineries as well as from other cellular processes display characteristic eukaryotic signatures or are clearly eukaryote-specific.
authors.affiliation: Equipe de Parasitologie Moléculaire et Cellulaire, LBP, UMR CNRS 6023, Université Blaise Pascal, 63177 Aubière Cedex, France. pierre.peyret@ lbp.univ-bpclermont.fr
authors.forename: P
authors.initials: P
authors.lastname: Peyret
authors.forename: M D
authors.initials: MD
authors.lastname: Katinka
authors.forename: S
authors.initials: S
authors.lastname: Duprat
authors.forename: F
authors.initials: F
authors.lastname: Duffieux
authors.forename: V
authors.initials: V
authors.lastname: Barbe
authors.forename: M
authors.initials: M
authors.lastname: Barbazanges
authors.forename: J
authors.initials: J
authors.lastname: Weissenbach
authors.forename: W
authors.initials: W
authors.lastname: Saurin
authors.forename: C P
authors.initials: CP
authors.lastname: Vivarès
mesh_terms: D000818:Animals; D001482:Base Composition; D002874:Chromosome Mapping; D016054:DNA, Protozoan / Q000032:analysis*; D009670:Encephalitozoon cuniculi / Q000235:genetics*; D023061:Gene Order; D017125:Genes, Protozoan; D007424:Intracellular Fluid / Q000469:parasitology; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D017422:Sequence Analysis, DNA / Q000379:methods; D020080:Tandem Repeat Sequences / Q000235:genetics; D016615:Telomere / Q000235:genetics
chemical_list: D016054:DNA, Protozoan