The Hsp40 chaperone Jjj1 is required for the nucleo-cytoplasmic recycling of preribosomal factors in <i>Saccharomyces cerevisiae</i>

Demoinet, Émilie; Jacquier, Alain; Lutfalla, Georges; Fromont‐Racine, Micheline

doi:10.1261/rna.585007

Cited by 51 publications

(81 citation statements)

References 37 publications

(72 reference statements)

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“…2B). As expected, the depletion of Arx1 did not significantly affect polysome profile but led to the appearance of halfmers, consistent with previous results obtained in the absence of Arx1 (Lebreton et al 2006;Demoinet et al 2007). In contrast, in the three double mutants P GAL1 -ECM1 pom34D, P GAL1 -ECM1 arx1D, and P GAL1 -ARX1 pom34D, we observed a decrease of the 60S large subunit levels, a decrease of polysomes, and the presence of halfmers.…”

Section: Resultssupporting

confidence: 92%

Ecm1 is a new pre-ribosomal factor involved in pre-60S particle export

Yao¹,

Demoinet²,

Saveanu³

et al. 2010

RNA

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In eukaryotes, ribosome biogenesis is a highly conserved process that starts in the nucleus and ends in the cytoplasm. In actively growing yeast cells, it is estimated that each nuclear pore complex (NPC) contributes to the export of about 25 pre-ribosomal particles per minute. Such an extremely active process requires several redundant export receptors for the pre-60S particles. Here, we report the identification of a novel pre-60S factor, Ecm1, which partially acts like Arx1 and becomes essential when the NPC function is affected. Ecm1 depletion, combined with the deletion of NPC components led to pre-60S retention in the nucleus. Functional links that we identified between Ecm1, 60S biogenesis, pre-60S export, and the NPC were correlated with physical interactions of Ecm1 with pre-60S particles and nucleoporins. These results support that Ecm1 is an additional factor involved in pre-60S export. While Ecm1 and Arx1 have redundant functions, overproduction of either one could not complement the absence of the other, whereas overproduction of Mex67 was able to partially restore the growth defect resulting from the absence of Ecm1 or Arx1. These data highlight the involvement of many factors acting together to export pre-60S particles.

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Section: Resultssupporting

confidence: 92%

Ecm1 is a new pre-ribosomal factor involved in pre-60S particle export

Yao¹,

Demoinet²,

Saveanu³

et al. 2010

RNA

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“…We selected several 60S-associated trans-acting factors and immunoprecipitated nascent 60S subunits with the tandem affinity purification (TAP) tag. Brx1 assembles into pre-60S at an early stage (37); Tif6 joins the nascent 60S from the nucleolus until almost the end of the maturation pathway (10, 38 -40); Arx1 is localized predominantly in the nucleus and released in the cytoplasm (41,42); and Rix1, which forms a complex with Rea1, is also localized predominantly in the nucleus and is involved in late rRNA processing and nuclear export of 60S subunits (43). Puf6 and Loc1 most strongly co-purified with Brx1, and the levels of Puf6 and Loc1 decreased in order from the Brx1-, Tif6-, Arx1-, and Rix1-containing nascent 60S subunits (Fig.…”

Section: Resultsmentioning

confidence: 99%

The Roles of Puf6 and Loc1 in 60S Biogenesis Are Interdependent, and Both Are Required for Efficient Accommodation of Rpl43

Yang

Ting

Liang

et al. 2016

Journal of Biological Chemistry

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Puf6 and Loc1 have two important functional roles in the cells, asymmetric mRNA distribution and ribosome biogenesis. Puf6 and Loc1 are localized predominantly in the nucleolus. They bind ASH1 mRNA, repress its translation, and facilitate the transport to the daughter cells. Asymmetric mRNA distribution is important for cell differentiation. Besides their roles in mRNA localization, Puf6 and Loc1 have been shown to be involved in 60S biogenesis. In puf6⌬ or loc1⌬ cells, pre-rRNA processing and 60S export are impaired and 60S subunits are underaccumulated. The functional studies of Puf6 and Loc1 have been focused on ASH1 mRNA pathway, but their roles in 60S biogenesis are still not clear. In this study, we found that Puf6 and Loc1 interact directly with each other and both proteins interact with the ribosomal protein Rpl43 (L43e). Notably, the roles of Puf6 and Loc1 in 60S biogenesis are interdependent, and both are required for efficient accommodation of Rpl43. Loc1 is further required to maintain the protein level of Rpl43. Additionally, the recruitment of Rpl43 is required for the release of Puf6 and Loc1. We propose that Puf6 and Loc1 facilitate Rpl43 loading and are sequentially released from 60S after incorporation of Rpl43 into ribosomes in yeast.Almost every process in a cell is mediated by proteins, the products of translating mRNA by ribosomes. Ribosomes are composed of two subunits, a small subunit and a large subunit, 40S and 60S, respectively, in eukaryotic cells. In Saccharomyces cerevisiae, the 40S and 60S subunits are assembled from a large primary 35 S rRNA transcribed by RNA polymerase I. Processing of this rRNA yields 5.8S, 18S, and 25S rRNAs. The 5S rRNA is transcribed by RNA polymerase III separately (see reviews in Refs. 1-4). In yeast, 5S, 5.8S, and 25S (28S in higher eukaryotes) rRNA assemble with 39 ribosomal proteins to make up the 60S subunit, whereas 18S rRNA and 33 ribosomal proteins constitute the 40S subunit (5-7).Ribosome biogenesis is necessary for cell growth and proliferation. The synthesis of ribosome is a complex pathway in which over 200 trans-acting factors are involved. Many of the RNA folding, protein assembly, and maturation events are hierarchical, requiring the correct completion of one event to progress to the next event. This is seen in the assembly of ribosomal proteins onto the RNA in bacterial ribosome assembly (8) as well as in cytoplasmic maturation of the large subunit in yeast (9, 10). In addition, trans-acting factors also perform quality control steps for the assembly of the protein synthesis machinery. Syo1 facilitates the synchronized import of the two 5S rRNA-binding proteins, Rpl5 and Rpl11, to ensure stoichiometric the incorporation of these two proteins into the pre-60S subunits and also works as an assembly platform for the 5S ribonucleoprotein (RNP) (11,12). Release of the anti-association factor Tif6 requires elongation factor-like Efl1 and tRNAlike Sdo1 to confirm the integrity of the P-site (13-15). Transacting factors on cytoplasmic pre-40S subuni...

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“…Initial insights into the late steps of maturation of these particles were provided by the discovery that the NTPases Drg1, Efl1, and Lsg1 are present on cytoplasmic pre-60S subunits (Becam et al 2001;Senger et al 2001;Kallstrom et al 2003;Hedges et al 2005;West et al 2005;Demoinet et al 2007;Meyer et al 2007;Pertschy et al 2007). At first it was puzzling to discover that mutations in or depletions of these cytoplasmic NTPases blocked earlier, nuclear steps in subunit biogenesis and nuclear Figure 10 Locations on late pre-60S ribosomes of export factors Mex67/ Mtr2, Nmd3, and Arx1 and assembly factors Tif6 and Rei1.…”

Section: Cytoplasmic Maturation Of Pre-40s and Pre-60s Subunitsmentioning

confidence: 99%

“…Interaction of L24 with Rei1 then enables docking of Rei1 to preribosomes. Rei1, together with the Hsp70 ATPase Ssa1/Ssa2, and its cofactor Jjj1, release the export adaptor Arx1 and its partner Alb1 from the polypeptide exit tunnel (Lebreton et al 2006b;Demoinet et al 2007;Meyer et al 2007Meyer et al , 2009Hung et al 2008).…”

Section: Cytoplasmic Maturation Of Pre-40s and Pre-60s Subunitsmentioning

confidence: 99%

Ribosome Biogenesis in the YeastSaccharomyces cerevisiae

2013

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Ribosomes are highly conserved ribonucleoprotein nanomachines that translate information in the genome to create the proteome in all cells. In yeast these complex particles contain four RNAs (.5400 nucleotides) and 79 different proteins. During the past 25 years, studies in yeast have led the way to understanding how these molecules are assembled into ribosomes in vivo. Assembly begins with transcription of ribosomal RNA in the nucleolus, where the RNA then undergoes complex pathways of folding, coupled with nucleotide modification, removal of spacer sequences, and binding to ribosomal proteins. More than 200 assembly factors and 76 small nucleolar RNAs transiently associate with assembling ribosomes, to enable their accurate and efficient construction. Following export of preribosomes from the nucleus to the cytoplasm, they undergo final stages of maturation before entering the pool of functioning ribosomes. Elaborate mechanisms exist to monitor the formation of correct structural and functional neighborhoods within ribosomes and to destroy preribosomes that fail to assemble properly. Studies of yeast ribosome biogenesis provide useful models for ribosomopathies, diseases in humans that result from failure to properly assemble ribosomes. TABLE OF CONTENTS Abstract 643Introduction 644

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The Hsp40 chaperone Jjj1 is required for the nucleo-cytoplasmic recycling of preribosomal factors in Saccharomyces cerevisiae

Cited by 51 publications

References 37 publications

Ecm1 is a new pre-ribosomal factor involved in pre-60S particle export

Ecm1 is a new pre-ribosomal factor involved in pre-60S particle export

The Roles of Puf6 and Loc1 in 60S Biogenesis Are Interdependent, and Both Are Required for Efficient Accommodation of Rpl43

Ribosome Biogenesis in the YeastSaccharomyces cerevisiae

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