Nascent 60S ribosomal subunits enter the free pool bound by Nmd3p

Ho, Jennifer Hei Ngam; Kallstrom, George; Johnson, Arlen

doi:10.1017/s1355838200001291

Cited by 51 publications

(65 citation statements)

References 36 publications

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“…Furthermore, the Nmd3 present in the arx1⌬ cells was essentially entirely bound to 60S ( Figure 3B), demonstrating that export of the Nmd3-60S complex is inhibited in the absence of Arx1. It should be noted that the Nmd3 present in the cytoplasm of wild-type cells is also bound to 60S subunits and must exist only transiently as a free protein during reimport into the nucleus (Ho et al, 2000a). Thus, the change in localization of Nmd3 reflects accumulation of an Nmd3-60S complex in the nucleus in arx1⌬ cells but not a change in the ratio of bound to unbound protein.…”

Section: Pre-60s Particles Loaded With Nmd3/crm1 and Mex67/ Mtr2 Accumentioning

confidence: 98%

Arx1 Is a Nuclear Export Receptor for the 60S Ribosomal Subunit in Yeast

Hung

Patel

et al. 2008

MBoC

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We previously showed that nuclear export of the large (60S) ribosomal subunit relies on Nmd3 in a Crm1-dependent manner. Recently the general mRNA export factor, the Mtr2/Mex67 heterodimer, was shown to act as an export receptor in parallel with Crm1. These observations raise the possibility that nuclear export of the 60S subunit in Saccharomyces cerevisiae requires multiple export receptors. Here, we show that the previously characterized 60S subunit biogenesis factor, Arx1, also acts as an export receptor for the 60S subunit. We found that deletion of ARX1 was synthetic lethal with nmd3 and mtr2 mutants and was synthetic sick with several nucleoporin mutants. Deletion of ARX1 led to accumulation of pre-60S particles in the nucleus that were enriched for Nmd3, Crm1, Mex67, and Mtr2, suggesting that in the absence of Arx1, 60S export is impaired even though the subunit is loaded with export receptors. Finally, Arx1 interacted with several nucleoporins in yeast two-hybrid as well as in vitro assays. These results show that Arx1 can directly bridge the interaction between the pre-60S particle and the NPC and thus is a third export receptor for the 60S subunit in yeast.

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Section: Pre-60s Particles Loaded With Nmd3/crm1 and Mex67/ Mtr2 Accumentioning

confidence: 98%

Arx1 Is a Nuclear Export Receptor for the 60S Ribosomal Subunit in Yeast

Hung

Patel

et al. 2008

MBoC

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“…However, this study additionally suggested that Sdo1 might induce dimerization of 60S subunits and raises the possibility that these 60S dimers might represent a storage form of the 60S subunit induced by stress conditions (Ma et al 2016). In the context of the observed binding of other maturation factors, such as Nmd3, Arx1, Alb1, Rei1, and eIF6, to mature 60S particles in vivo (Ho et al 2000a;Merl et al 2010), this is an intriguing hypothesis. However, further experimental evidence is required to establish the physiological significance of this observation.…”

Section: The Mechanism Of Eif6 Releasementioning

confidence: 99%

Mechanistic insight into eukaryotic 60S ribosomal subunit biogenesis by cryo-electron microscopy

Greber

2016

RNA

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Eukaryotic ribosomes, the protein-producing factories of the cell, are composed of four ribosomal RNA molecules and roughly 80 proteins. Their biogenesis is a complex process that involves more than 200 biogenesis factors that facilitate the production, modification, and assembly of ribosomal components and the structural transitions along the maturation pathways of the preribosomal particles. Here, I review recent structural and mechanistic insights into the biogenesis of the large ribosomal subunit that were furthered by cryo-electron microscopy of natively purified pre-60S particles and in vitro reconstituted ribosome assembly factor complexes. Combined with biochemical, genetic, and previous structural data, these structures have provided detailed insights into the assembly and maturation of the central protuberance of the 60S subunit, the network of biogenesis factors near the ribosomal tunnel exit, and the functional activation of the large ribosomal subunit during cytoplasmic maturation.

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“…When we tested hNMD3 binding to 40S subunits, as expected, the majority of hNMD3 stayed in the supernatant although a minor portion was recovered in the 40S pellet (data not shown). However, in vivo, yeast Nmd3p exclusively binds to 60S subunits (Ho and Johnson, 1999;Ho et al, 2000a). To confirm that recombinant hNMD3 preferentially binds to 60S subunits in vitro, we incubated hNMD3 with a mixture of equal amounts of 40S and 60S subunits.…”

Section: Recombinant Hnmd3 Binds To 60s Ribosomal Subunits and Can DImentioning

confidence: 99%

“…Furthermore, Nmd3p is a shuttling protein that contains a nuclear localization signal (NLS) and a leucine-rich NES in its C-terminal domain (Ho et al, 2000b;Gadal et al, 2001). At steady state, Nmd3p localizes predominantly to the cytoplasm where it is bound to free 60S subunits (Ho and Johnson, 1999;Ho et al, 2000a). An NES deletion mutant of Nmd3p accumulates in the nucleus and, if overexpressed, interferes with nuclear export of pre-60S particles.…”

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confidence: 99%

Biogenesis and nuclear export of ribosomal subunits in higher eukaryotes depend on the CRM1 export pathway

Thomas

Kutay

2003

Journal of Cell Science

167

188

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The production of ribosomes constitutes a major biosynthetic task for cells. Eukaryotic small and large ribosomal subunits are assembled in the nucleolus and independently exported to the cytoplasm. Most nuclear export pathways require RanGTP-binding export receptors. We analyzed the role of CRM1, the export receptor for leucine-rich nuclear export signals (NES), in the biogenesis of ribosomal subunits in vertebrate cells. Inhibition of the CRM1 export pathway led to a defect in nuclear export of both 40S and 60S subunits in HeLa cells. Moreover, the export of newly made ribosomal subunits in Xenopus oocytes was efficiently and specifically competed by BSA-NES conjugates. The CRM1 dependence of 60S subunit export suggested a conserved function for NMD3, a factor proposed to be a 60S subunit export adaptor in yeast. Indeed, we observed that nuclear export of human NMD3(hNMD3) is sensitive to leptomycin B (LMB), which inactivates CRM1. It had,however, not yet been demonstrated that Nmd3 can interact with CRM1. Using purified recombinant proteins we have shown here that hNMD3 binds to CRM1 directly, in a RanGTP-dependent manner, by way of a C-terminal NES sequence. Our results suggest that the functions of CRM1 and NMD3 in ribosomal subunit export are conserved from yeast to higher eukaryotes.

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Nascent 60S ribosomal subunits enter the free pool bound by Nmd3p

Cited by 51 publications

References 36 publications

Arx1 Is a Nuclear Export Receptor for the 60S Ribosomal Subunit in Yeast

Arx1 Is a Nuclear Export Receptor for the 60S Ribosomal Subunit in Yeast

Mechanistic insight into eukaryotic 60S ribosomal subunit biogenesis by cryo-electron microscopy

Biogenesis and nuclear export of ribosomal subunits in higher eukaryotes depend on the CRM1 export pathway

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