title: A novel active DNA topoisomerase I in Leishmania donovani.
abstract: A common feature shared by type I DNA topoisomerases is the presence of a "serine, lysine, X, X, tyrosine" motif as conventional enzyme active site. Preliminary data have shown that Leishmania donovani DNA topoisomerase I gene (LdTOP1A) lacked this conserved motif, giving rise to different theories about the reconstitution of an active DNA topoisomerase I in this parasite. We, herein, describe the molecular cloning of a new DNA topoisomerase I gene from L. donovani (LdTOP1B) containing the highly conserved serine, lysine, X, X, tyrosine motif. DNA topoisomerase I activity was detected only when both genes (LdTOP1A and LdTOP1B) were co-expressed in a yeast expression system, suggesting the existence of a dimeric DNA topoisomerase I in Leishmania parasites.
authors.affiliation: Departamento de Farmacologia y Toxicologia (INTOXCAL), Universidad de León, Campus de Vegazana sn, 24071 León, Spain.
authors.forename: Héctor
authors.initials: H
authors.lastname: Villa
authors.forename: Ana R
authors.initials: AR
authors.lastname: Otero Marcos
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Reguera
authors.forename: Rafael
authors.initials: R
authors.lastname: Balaña-Fouce
authors.forename: Carlos
authors.initials: C
authors.lastname: García-Estrada
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Pérez-Pertejo
authors.forename: Babu L
authors.initials: BL
authors.lastname: Tekwani
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Myler
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Stuart
authors.forename: Mary-Ann
authors.initials: MA
authors.lastname: Bjornsti
authors.forename: David
authors.initials: D
authors.lastname: Ordóñez
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D004264:DNA Topoisomerases, Type I / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017125:Genes, Protozoan; D006801:Humans; D007893:Leishmania donovani / Q000201:enzymology*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D004264:DNA Topoisomerases, Type I