title: Touching from a distance.
abstract: The nuclear pore complex (NPC) is the sole mediator of bidirectional nucleo-cytoplasmic transport and is also an important scaffold for chromatin organization and transcriptional regulation. Proteomic studies of numerous diverse eukaryotic species initially characterized the NPC as built with a number of remarkably similar structural features, suggesting its status as an ancient and conserved eukaryotic cell component. However, further detailed analyses now suggest that several key specific NPC features have a more convoluted evolutionary history than initially assumed. Recently we reported on TbNup92, a component in trypanosomes of one such conserved structural feature, a basket-like structure on the nuclear face of the NPC. We showed that TbNup92 has similar roles to nuclear basket proteins from yeasts and animals (Mlp and Tpr, respectively) in interacting with both the NPC and the mitotic spindle. However, comparative genomics suggests that TbNup92 and Mlp/Tpr may be products of distinct evolutionary histories, raising the possibility that these gene products are analogs rather than direct orthologs. Taken together with recent evidence for divergence in the nuclear lamina and kinetochores, it is apparent that the trypanosome nucleus functions by employing several novel or highly divergent protein complexes in parallel with conserved elements. These findings have major implications for how the trypanosomatid nucleus operates and the evolution of hierarchical nuclear organization.
authors.affiliation: a Division of Biological Chemistry and Drug Discovery; University of Dundee, Dundee, UK.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Holden
authors.forename: Ludek
authors.initials: L
authors.lastname: Koreny
authors.forename: Steven
authors.initials: S
authors.lastname: Kelly
authors.forename: Brian T
authors.initials: BT
authors.lastname: Chait
authors.forename: Michael P
authors.initials: MP
authors.lastname: Rout
authors.forename: Mark C
authors.initials: MC
authors.lastname: Field
authors.forename: Samson O
authors.initials: SO
authors.lastname: Obado
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D008938:Mitosis / Q000502:physiology; D009685:Nuclear Envelope / Q000378:metabolism; D022022:Nuclear Pore / Q000378:metabolism*; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D015800:Protozoan Proteins / Q000378:metabolism; D008941:Spindle Apparatus / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000378:metabolism
chemical_list: D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D015800:Protozoan Proteins
keywords: Mlp; Trypanosoma brucei; chromosome segregation; mitosis; mitotic spindle; nuclear basket; nuclear evolution; nuclear pore complex