title: Identification of a novel nucleocytoplasmic shuttling RNA helicase of trypanosomes.
abstract: Gene expression in trypanosomes is controlled mostly by post-transcriptional pathways. Little is known about the components of mRNA nucleocytoplasmic export routes in these parasites. Comparative genomics has shown that the mRNA transport pathway is the least conserved pathway among eukaryotes. Nonetheless, we identified a RNA helicase (Hel45) that is conserved across eukaryotes and similar to shuttling proteins involved in mRNA export. We used in silico analysis to predict the structure of Trypanosoma cruzi Hel45, including the N-terminal domain and the C-terminal domain, and our findings suggest that this RNA helicase can form complexes with mRNA. Hel45 was present in both nucleus and cytoplasm. Electron microscopy showed that Hel45 is clustered close to the cytoplasmic side of nuclear pore complexes, and is also present in the nucleus where it is associated with peripheral compact chromatin. Deletion of a predicted Nuclear Export Signal motif led to the accumulation of Hel45ΔNES in the nucleus, indicating that Hel45 shuttles between the nucleus and the cytoplasm. This transport was dependent on active transcription but did not depend on the exportin Crm1. Knockdown of Mex67 in T. brucei caused the nuclear accumulation of the T. brucei ortholog of Hel45. Indeed, Hel45 is present in mRNA ribonucleoprotein complexes that are not associated with polysomes. It is still necessary to confirm the precise function of Hel45. However, this RNA helicase is associated with mRNA metabolism and its nucleocytoplasmic shuttling is dependent on an mRNA export route involving Mex67 receptor.
authors.affiliation: Instituto Carlos Chagas, FIOCRUZ, Curitiba, Brazil.
authors.forename: Alexandre Haruo
authors.initials: AH
authors.lastname: Inoue
authors.affiliation: Instituto Carlos Chagas, FIOCRUZ, Curitiba, Brazil; Departamento de Biologia Celular e Molecular, Universidade Federal do Paraná, Curitiba, Brazil.
authors.forename: Mariana
authors.initials: M
authors.lastname: Serpeloni
authors.affiliation: Instituto Carlos Chagas, FIOCRUZ, Curitiba, Brazil.
authors.forename: Priscila Mazzocchi
authors.initials: PM
authors.lastname: Hiraiwa
authors.affiliation: Departamento de Microbiologia, Universidade Estadual de Londrina, Londrina, Brazil.
authors.forename: Sueli Fumie
authors.initials: SF
authors.lastname: Yamada-Ogatta
authors.affiliation: Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil.
authors.forename: João Renato Carvalho
authors.initials: JR
authors.lastname: Muniz
authors.affiliation: Departamento de Biologia Celular e Parasitologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Maria Cristina Machado
authors.initials: MC
authors.lastname: Motta
authors.affiliation: Instituto Carlos Chagas, FIOCRUZ, Curitiba, Brazil; National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Newton Medeiros
authors.initials: NM
authors.lastname: Vidal
authors.affiliation: Instituto Carlos Chagas, FIOCRUZ, Curitiba, Brazil.
authors.forename: Samuel
authors.initials: S
authors.lastname: Goldenberg
authors.affiliation: Instituto Carlos Chagas, FIOCRUZ, Curitiba, Brazil.
authors.forename: Andréa Rodrigues
authors.initials: AR
authors.lastname: Avila
mesh_terms: D000595:Amino Acid Sequence; D061245:Axenic Culture; D020134:Catalytic Domain; D002467:Cell Nucleus / Q000201:enzymology; D017124:Conserved Sequence; D003593:Cytoplasm / Q000201:enzymology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D022022:Nuclear Pore / Q000201:enzymology; D021381:Protein Transport; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020365:RNA Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D034443:RNA Transport; D012333:RNA, Messenger / Q000378:metabolism; D012261:Ribonucleoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014349:Trypanosoma cruzi / Q000201:enzymology*
chemical_list: D015800:Protozoan Proteins; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D020365:RNA Helicases