The quantitative assessment of the role played by basic amino acid clusters in the nuclear uptake of human ribosomal protein L7

Tai, Lin-Ru; Chou, Chang-Wei; Lee, I‐Fang; Kirby, Ralph; Lin, Alan

doi:10.1016/j.yexcr.2012.12.007

Cited by 6 publications

(1 citation statement)

References 25 publications

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“…This result was not surprising considering that this unusual extension is likely to affect folding of the globular region of L7. Moreover, the N-terminus of L7 was previously shown to contain monopartite and bipartite nuclear localization sequences, deletion of which could prevent nuclear import and assembly of L7, leading to its turnover (Chou et al 2010;Tai et al 2013). Since destabilization of L7 is the same as its depletion, these truncation mutations do not provide any novel information about potential roles of the L7 extension and were not studied further.…”

Section: Resultsmentioning

confidence: 99%

The N-terminal extension of yeast ribosomal protein L8 is involved in two major remodeling events during late nuclear stages of 60S ribosomal subunit assembly

Tutuncuoglu

Jakovljevic

et al. 2016

RNA

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Assaying effects on pre-rRNA processing and ribosome assembly upon depleting individual ribosomal proteins (r-proteins) provided an initial paradigm for assembly of eukaryotic ribosomes in vivo-that each structural domain of ribosomal subunits assembles in a hierarchical fashion. However, two features suggest that a more complex pathway may exist: (i) Some r-proteins contain extensions that reach long distances across ribosomes to interact with multiple rRNA domains as well as with other r-proteins. (ii) Individual r-proteins may assemble in a stepwise fashion. For example, the globular domain of an r-protein might assemble separately from its extensions. Thus, these extensions might play roles in assembly that could not be revealed by depleting the entire protein. Here, we show that deleting or mutating extensions of r-proteins L7 (uL30) and L35 (uL29) from yeast reveal important roles in early and middle steps during 60S ribosomal subunit biogenesis. Detailed analysis of the N-terminal terminal extension of L8 (eL8) showed that it is necessary for late nuclear stages of 60S subunit assembly involving two major remodeling events: removal of the ITS2 spacer; and reorganization of the central protuberance (CP) containing 5S rRNA and r-proteins L5 (uL18) and L11 (uL5). Mutations in the L8 extension block processing of 7S pre-rRNA, prevent release of assembly factors Rpf2 and Rrs1 from pre-ribosomes, which is required for rotation of the CP, and block association of Sda1, the Rix1 complex, and the Rea1 ATPase involved in late steps of remodeling.

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Section: Resultsmentioning

confidence: 99%

The N-terminal extension of yeast ribosomal protein L8 is involved in two major remodeling events during late nuclear stages of 60S ribosomal subunit assembly

Tutuncuoglu

Jakovljevic

et al. 2016

RNA

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On the expansion of ribosomal proteins and RNAs in eukaryotes

et al. 2014

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While the ribosome constitution is similar in all biota, there is a considerable increase in size of both ribosomal proteins (RPs) and RNAs in eukaryotes as compared to archaea and bacteria. This is pronounced in the large (60S) ribosomal subunit (LSU). In addition to enlargement (apparently maximized already in lower eukarya), the RP changes include increases in fraction, segregation and clustering of basic residues, and decrease in hydrophobicity. The acidic fraction is lower in eukaryote as compared to prokaryote RPs. In all eukaryote groups tested, the LSU RPs have significantly higher content of basic residues and homobasic segments than the SSU RPs. The vertebrate LSU RPs have much higher sequestration of basic residues than those of bacteria, archaea and even of the lower eukarya. The basic clusters are highly aligned in the vertebrate, but less in the lower eukarya, and only within families in archaea and bacteria. Increase in the basicity of RPs, besides helping transport to the nucleus, should promote stability of the assembled ribosome as well as the association with translocons and other intracellular matrix proteins. The size and GC nucleotide bias of the expansion segments of large LSU rRNAs also culminate in the vertebrate, and should support ribosome association with the endoplasmic reticulum and other intracellular networks. However, the expansion and nucleotide bias of eukaryote LSU rRNAs do not clearly correlate with changes in ionic parameters of LSU ribosomal proteins.

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Transportin‐1 and Transportin‐2: Protein nuclear import and beyond

2014

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Edited by Ulrike KutayKeywords: Transportin Importins Karyopherins Nuclear import Nucleo-cytoplasmic transport NLS Kap104p Transportin-1 Transportin-2 Karyopherin-b2 hnRNP A1 FUS a b s t r a c t Nearly 20 years after its identification as a new b-karyopherin mediating the nuclear import of the RNA-binding protein hnRNP A1, Transportin-1 is still commonly overlooked in comparison with its best known cousin, Importin-b. Transportin-1 is nonetheless a considerable player in nucleo-cytoplasmic transport. Over the past few years, significant progress has been made in the characterization of the nuclear localization signals (NLSs) that Transportin-1 recognizes, thereby providing the molecular basis of its diversified repertoire of cargoes. The recent discovery that mutations in the Transportin-dependent NLS of FUS cause mislocalization of this protein and result in amyotrophic lateral sclerosis illustrates the importance of Transportin-dependent import for human health. Besides, new functions of Transportin-1 are emerging in processes other than nuclear import. Here, we summarize what is known about Transportin-1 and the related b-karyopherin Transportin-2. Ó 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved. Basis of protein nucleo-cytoplasmic transportActive nucleo-cytoplasmic transport of proteins is mostly carried out by b-karyopherins, a family of factors functionally divided into importins and exportins. Importins bind to the nuclear localization signal (NLS) of their cargoes in the cytoplasm, either directly or through an adaptor. The importin/cargo complexes cross the nuclear pore complex (NPC) through the interactions of the importin with nucleoporins. In the nucleus, importins are bound by Ran-GTP, which releases the cargo. Importins are then recycled to the cytoplasm in association with Ran-GTP. On the cytoplasmic face of the NPC, Ran hydrolyzes its bound GTP into GDP and dissociates, freeing the importin for a new import cycle (see for example [1] for review). Exportins work in a similar way but in reverse. In the nucleus, exportins cooperatively bind Ran-GTP and a cargo featuring a fitting nuclear export signal (NES). Once the trimeric complexes reach the cytoplasm, they are dissociated and free exportins return to the nucleus to complete the cycle (see for example [2] for review). Thus, while Ran-GTP binding causes importins to release their cargoes, it is required for exportins to bind theirs. Neither importins nor exportins have significant binding affinity for the GDP-bound form of Ran. Therefore, the directionality of the transfers is maintained by mechanisms that ensure that nuclear Ran is bound to GTP and cytoplasmic Ran to GDP. The nuclear part of this task is carried out by the chromatin-associated guanine exchange factor RCC1, which promotes the exchange of GDP for GTP on nuclear Ran. Three factors located on the cytosolic face of the NPC (RanBP1, RanBP2, and RanGAP) collaborate to ensure the hydrolysis of Ran-bound GTP by Ran as soon as it goes ou...

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The quantitative assessment of the role played by basic amino acid clusters in the nuclear uptake of human ribosomal protein L7

Cited by 6 publications

References 25 publications

The N-terminal extension of yeast ribosomal protein L8 is involved in two major remodeling events during late nuclear stages of 60S ribosomal subunit assembly

The N-terminal extension of yeast ribosomal protein L8 is involved in two major remodeling events during late nuclear stages of 60S ribosomal subunit assembly

On the expansion of ribosomal proteins and RNAs in eukaryotes

Transportin‐1 and Transportin‐2: Protein nuclear import and beyond

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