Nuclear pore complex evolution: a trypanosome Mlp analogue functions in chromosomal segregation but lacks transcriptional barrier activity

Jennifer M. Holden, Ludek Koreny, Samson Obado, Alexander V. Ratushny, Wei-Ming Chen, Jung-Hsien Chiang, Steven Kelly, Brian T. Chait, John D. Aitchison, Michael P. Rout, Mark C. Field

    Research output: Contribution to journalArticlepeer-review

    17 Citations (Scopus)

    Abstract

    The nuclear pore complex (NPC) has dual roles in nucleocytoplasmic transport and chromatin organization. In many eukaryotes the coiled-coil Mlp/Tpr proteins of the NPC nuclear basket have specific functions in interactions with chromatin and defining specialized regions of active transcription, whereas Mlp2 associates with the mitotic spindle/NPC in a cell cycle-dependent manner. We previously identified two putative Mlp-related proteins in African trypanosomes, TbNup110 and TbNup92, the latter of which associates with the spindle. We now provide evidence for independent ancestry for TbNup92/TbNup110 and Mlp/Tpr proteins. However, TbNup92 is required for correct chromosome segregation, with knockout cells exhibiting microaneuploidy and lowered fidelity of telomere segregation. Further, TbNup92 is intimately associated with the mitotic spindle and spindle anchor site but apparently has minimal roles in control of gene transcription, indicating that TbNup92 lacks major barrier activity. TbNup92 therefore acts as a functional analogue of Mlp/Tpr proteins, and, together with the lamina analogue NUP-1, represents a cohort of novel proteins operating at the nuclear periphery of trypanosomes, uncovering complex evolutionary trajectories for the NPC and nuclear lamina.
    Original languageEnglish
    Pages (from-to)1421-1436
    Number of pages16
    JournalMolecular Biology of the Cell
    Volume25
    Issue number9
    DOIs
    Publication statusPublished - 1 May 2014

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