Basic Domains Target Protein Subunits of the RNase MRP Complex to the Nucleolus Independently of Complex Association

Eenennaam, Hans van; Heijden, Annemarie van der; Janßen, Rolf; Venrooij, Walther J. van; Pruijn, Ger J. M.

doi:10.1091/mbc.12.11.3680

Cited by 25 publications

(11 citation statements)

References 32 publications

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“…Second, partially assembled parts of the exosome may enter the nucleus and assemble into a complete exosome in the nucleoplasm or nucleolus. All of these basic elements may also be involved in nucleolar targeting of the exosome, because elements rich in basic residues have been demonstrated to play an essential role in nucleolar accumulation (24).…”

Section: Discussionmentioning

confidence: 99%

The Association of the Human PM/Scl-75 Autoantigen with the Exosome Is Dependent on a Newly Identified N Terminus

Raijmakers¹,

Egberts²,

Venrooij³

et al. 2003

Journal of Biological Chemistry

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The exosome is a complex of 3 3 5 exoribonucleases that functions in a variety of cellular processes, all concerning the processing or degradation of RNA. Paradoxically, the previously described cDNA for the human autoantigenic exosome subunit PM/Scl-75 (Alderuccio, F., Chan, E. K., and Tan, E. M. (1991) J. Exp. Med. 173, 941-952) encodes a polypeptide that failed to interact with the exosome complex. Here, we describe the cloning of a more complete cDNA for PM/Scl-75 encoding 84 additional amino acids at its N terminus. We show that only the longer polypeptide is able to associate with the exosome complex. This interaction is most likely mediated by protein-protein interactions with two other exosome subunits, hRrp46p and hRrp41p, one of which was confirmed in a mammalian two-hybrid system. In addition we show that the putative nuclear localization signal present in the C-terminal region of PM/Scl-75 is sufficient, although not essential for nuclear localization of the protein. Moreover, the deletion of this element abrogated the nucleolar accumulation of PM/Scl-75, although its association with the exosome was not disturbed. This suggests that this basic element of PM/ Scl-75 plays a role in targeting the exosome to the nucleolus.The PM/Scl-75 protein (encoded by gene PMSCL1) was the first protein of the polymyositis/scleroderma (PM/Scl) 1 complex to be characterized (1). The PM/Scl complex was originally described as a complex consisting of 11-16 proteins, some of which are autoantigenic in autoimmune patients. Autoantibodies to this complex are most frequently found in patients suffering from PM/Scl overlap syndrome but are also present in some patients with myositis or scleroderma alone (2, 3). The subunits PM/Scl-75, PM/Scl-100, and hRrp4p have been shown to carry the main autoantigenic determinants for polymyositis/ scleroderma overlap syndrome autoantibodies (4, 5). Following the identification of two of its subunits, PM/Scl-75 and PM/Scl-100 (6, 7), and their characterization as putative exoribonucleases (8), the PM/Scl complex was shown to be related to the yeast exosome, a complex containing ϳ10 exoribonucleases (9).The exosome functions in a variety of processes involving the 3Ј 3 5Ј processing or degradation of RNA. Among these processes are the maturation of 5.8 S rRNA (10 -12), the processing of many small nuclear and nucleolar RNAs (13-15), and the turnover of different types of mRNAs (16,17), especially the AU-rich element containing mRNAs (18,19). PM/Scl-75 has been suggested to be an AU-rich element binding protein, involved in the recruitment of the exosome to this class of mRNAs (19).Like five other exosome proteins, PM/Scl-75 contains an RNase PH domain, which is homologous to the prokaryotic 3Ј-5Ј exoribonuclease RNase PH. Based on mutual interactions between exosome components and structural similarity with the bacterial protein polynucleotide phosphorylase (PNPase), a component of the bacterial degradosome, recently a model for the structure of the human exosome was generated. In this mo...

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Section: Discussionmentioning

confidence: 99%

The Association of the Human PM/Scl-75 Autoantigen with the Exosome Is Dependent on a Newly Identified N Terminus

Raijmakers¹,

Egberts²,

Venrooij³

et al. 2003

Journal of Biological Chemistry

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“…Basic stretches of amino acids have been identified as elements that may mediate nucleolar retention of proteins through interaction with polyanions (39), and in the case of TOP1, the 120 amino acids centered about Lys-117 are 35% Lys and Arg (28% Asp and Glu). It is possible that SUMO conjugates may disrupt this highly charged region, effectively dislodging TOP1 from binding sites in nucleoli and enabling a large part to continuously partition into the nucleoplasm under basal conditions.…”

Section: Discussionmentioning

confidence: 99%

Sumoylation of Topoisomerase I Is Involved in Its Partitioning between Nucleoli and Nucleoplasm and Its Clearing from Nucleoli in Response to Camptothecin

Rallabhandi

Hashimoto

et al. 2002

Journal of Biological Chemistry

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Previous studies identified a small fraction of putatively sumoylated topoisomerase I (TOP1) under basal conditions (ϳ1%), and anticancer camptothecins that trap the TOP1-DNA covalent intermediate markedly increase the sumoylation of TOP1 (<10%). To study the role of the sumoylation of TOP1, we mutated sites on green fluorescent protein (GFP)-TOP1 corresponding to the consensus sequence for protein sumoylation (⌿KXE, where ⌿ is a hydrophobic residue) and assayed the mutants for basal and camptothecin-induced sumoylation. Only one of the eight mutants, K117R, located in the highly charged NH 2 -terminal region, showed a substantial reduction (ϳ5-fold) in basal and camptothecin-induced sumoylation; thus, Lys-117 appears to be the major sumoylation site. A triple mutant having the ⌿KXE sequences flanking K117R additionally mutated (K103R/ K117R/K153R) showed little if any sumoylation, but was degraded like wild-type GFP-TOP1 during camptothecin treatment. However, K103R/K117R/K153R-GFP-TOP1 was markedly concentrated within nucleoli, depleted from the remainder of nucleus, and failed to be cleared from nucleoli in response to camptothecin treatment. These data are consistent with a model wherein basal transient sumoylation of the NH 2 -terminal, highly charged, disordered region prevents TOP1 binding to sites in nucleoli, thus driving it to bind in the nucleoplasm; and camptothecin treatment, which increases TOP1 sumoylation, further shifts the binding resulting in delocalization of TOP1 from nucleoli to nucleoplasm.

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“…Nuclear or nucleolar location was also often observed for TAN deletion-YFP constructs. We cannot currently address the significance of this localization but we note that some proteins containing basic stretches, such as those found in TAN, passively diffuse into and are preferentially retained in the nucleolus (van Eenennaam et al, 2001;Meng et al, 2007). We took advantage of nuclear, nucleolar and/or cytoplasmic localization along with CDS localization to identify plants and cells in which TAN-YFP deletion derivatives were expressed.…”

Section: Two Distinct Regions Of Tangled Are Required For Early and Lmentioning

confidence: 99%

Tangled localization at the cortical division site of plant cells occurs by several mechanisms

Rasmussen

Sun

Smith

2011

Journal of Cell Science

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Summary TANGLED (TAN) is the founding member of a family of plant-specific proteins required for correct orientation of the division plane. Arabidopsis thaliana TAN is localized before prophase until the end of cytokinesis at the cortical division site (CDS), where it appears to help guide the cytokinetic apparatus towards the cortex. We show that TAN is actively recruited to the CDS by distinct mechanisms before and after preprophase band (PPB) disassembly. Colocalization with the PPB is mediated by one region of TAN, whereas another region mediates its recruitment to the CDS during cytokinesis. This second region binds directly to POK1, a kinesin that is required for TAN localization. Although this region of TAN is recruited to the CDS during cytokinesis without first colocalizing with the PPB, pharmacological evidence indicates that the PPB is nevertheless required for both early and late localization of TAN at the CDS. Finally, we show that phosphatase activity is required for maintenance of early but not late TAN localization at the CDS. We propose a new model in which TAN is actively recruited to the CDS by several mechanisms, indicating that the CDS is dynamically modified from prophase through to the completion of cytokinesis.

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Basic Domains Target Protein Subunits of the RNase MRP Complex to the Nucleolus Independently of Complex Association

Cited by 25 publications

References 32 publications

The Association of the Human PM/Scl-75 Autoantigen with the Exosome Is Dependent on a Newly Identified N Terminus

The Association of the Human PM/Scl-75 Autoantigen with the Exosome Is Dependent on a Newly Identified N Terminus

Sumoylation of Topoisomerase I Is Involved in Its Partitioning between Nucleoli and Nucleoplasm and Its Clearing from Nucleoli in Response to Camptothecin

Tangled localization at the cortical division site of plant cells occurs by several mechanisms

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