scholarly journals NSR1 is required for pre-rRNA processing and for the proper maintenance of steady-state levels of ribosomal subunits.

1992 ◽  
Vol 12 (9) ◽  
pp. 3865-3871 ◽  
Author(s):  
W C Lee ◽  
D Zabetakis ◽  
T Mélèse
Keyword(s):  
Nuclear Localization ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Protein Translation ◽  
Striking Similarity ◽  
Growth Defect ◽  
Nuclear Localization Sequence ◽  
Rrna Processing ◽  
Ribosomal Subunits ◽  
Localization Sequence

NSR1 is a yeast nuclear localization sequence-binding protein showing striking similarity in its domain structure to nucleolin. Cells lacking NSR1 are viable but have a severe growth defect. We show here that NSR1, like nucleolin, is involved in ribosome biogenesis. The nsr1 mutant is deficient in pre-rRNA processing such that the initial 35S pre-rRNA processing is blocked and 20S pre-rRNA is nearly absent. The reduced amount of 20S pre-rRNA leads to a shortage of 18S rRNA and is reflected in a change in the distribution of 60S and 40S ribosomal subunits; there is no free pool of 40S subunits, and the free pool of 60S subunits is greatly increased in size. The lack of free 40S subunits or the improper assembly of these subunits causes the nsr1 mutant to show sensitivity to the antibiotic paromomycin, which affects protein translation, at concentrations that do not affect the growth of the wild-type strain. Our data support the idea that NSR1 is involved in the proper assembly of pre-rRNA particles, possibly by bringing rRNA and ribosomal proteins together by virtue of its nuclear localization sequence-binding domain and multiple RNA recognition motifs. Alternatively, NSR1 may also act to regulate the nuclear entry of ribosomal proteins required for proper assembly of pre-rRNA particles.

NSR1 is required for pre-rRNA processing and for the proper maintenance of steady-state levels of ribosomal subunits

1992 ◽  
Vol 12 (9) ◽  
pp. 3865-3871
Author(s):  
W C Lee ◽  
D Zabetakis ◽  
T Mélèse
Keyword(s):  
Nuclear Localization ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Protein Translation ◽  
Striking Similarity ◽  
Growth Defect ◽  
Nuclear Localization Sequence ◽  
Rrna Processing ◽  
Ribosomal Subunits ◽  
Localization Sequence

NSR1 is a yeast nuclear localization sequence-binding protein showing striking similarity in its domain structure to nucleolin. Cells lacking NSR1 are viable but have a severe growth defect. We show here that NSR1, like nucleolin, is involved in ribosome biogenesis. The nsr1 mutant is deficient in pre-rRNA processing such that the initial 35S pre-rRNA processing is blocked and 20S pre-rRNA is nearly absent. The reduced amount of 20S pre-rRNA leads to a shortage of 18S rRNA and is reflected in a change in the distribution of 60S and 40S ribosomal subunits; there is no free pool of 40S subunits, and the free pool of 60S subunits is greatly increased in size. The lack of free 40S subunits or the improper assembly of these subunits causes the nsr1 mutant to show sensitivity to the antibiotic paromomycin, which affects protein translation, at concentrations that do not affect the growth of the wild-type strain. Our data support the idea that NSR1 is involved in the proper assembly of pre-rRNA particles, possibly by bringing rRNA and ribosomal proteins together by virtue of its nuclear localization sequence-binding domain and multiple RNA recognition motifs. Alternatively, NSR1 may also act to regulate the nuclear entry of ribosomal proteins required for proper assembly of pre-rRNA particles.

scholarly journals The nucleolar DExD/H protein Hel66 is involved in ribosome biogenesis in Trypanosoma brucei

2021 ◽  
Author(s):  
Majeed Bakari-Soale ◽  
Nonso Josephat Ikenge ◽  
Marion Scheibe ◽  
Falk Butter ◽  
Nicola Gail Jones ◽  
...  
Keyword(s):  
Ribosomal Rna ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Growth Defect ◽  
Rrna Processing ◽  
Ribosomal Subunits ◽  
Comprehensive Picture ◽  
Severe Growth Defect ◽  
H Protein ◽  
Severe Growth

The biosynthesis of ribosomes is a complex cellular process involving ribosomal RNA, ribosomal proteins and several further trans-acting factors. DExD/H box proteins constitute the largest family of trans-acting protein factors involved in this process. Several members of this protein family have been directly implicated in ribosome biogenesis in yeast. In trypanosomes, ribosome biogenesis differs in several features from the process described in yeast. Here, we have identified the DExD/H box helicase Hel66 as being involved in ribosome biogenesis. The protein is unique to Kinetoplastida, localises to the nucleolus and its depletion via RNAi caused a severe growth defect. Loss of the protein resulted in a decrease of global translation and accumulation of rRNA processing intermediates for both the small and large ribosomal subunits. Only a few factors involved in trypanosome rRNA biogenesis have been described so far and our findings contribute to gaining a more comprehensive picture of this essential process.

scholarly journals The Nucleolar DExD/H Protein Hel66 is Involved in Ribosome Biogenesis in Trypanosoma Brucei

2021 ◽  
Author(s):  
Majeed Bakari-Soale ◽  
Nonso Josephat Ikenga ◽  
Marion Scheibe ◽  
Falk Butter ◽  
Nicola Gail Jones ◽  
...  
Keyword(s):  
Ribosomal Rna ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Growth Defect ◽  
Rrna Processing ◽  
Ribosomal Subunits ◽  
Comprehensive Picture ◽  
Severe Growth Defect ◽  
H Protein ◽  
Severe Growth

Abstract The biosynthesis of ribosomes is a complex cellular process involving ribosomal RNA, ribosomal proteins and several further trans-acting factors. DExD/H box proteins constitute the largest family of trans-acting protein factors involved in this process. Several members of this protein family have been directly implicated in ribosome biogenesis in yeast. In trypanosomes, ribosome biogenesis differs in several features from the process described in yeast. Here, we have identified the DExD/H box helicase Hel66 as being involved in ribosome biogenesis. The protein is unique to Kinetoplastida, localises to the nucleolus and its depletion via RNAi caused a severe growth defect. Loss of the protein resulted in a decrease of global translation and accumulation of rRNA processing intermediates for both the small and large ribosomal subunits. Only a few factors involved in trypanosome rRNA biogenesis have been described so far and our findings contribute to gaining a more comprehensive picture of this essential process.

scholarly journals The nucleolar DExD/H protein Hel66 is involved in ribosome biogenesis in Trypanosoma brucei

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Majeed Bakari-Soale ◽  
Nonso Josephat Ikenga ◽  
Marion Scheibe ◽  
Falk Butter ◽  
Nicola G. Jones ◽  
...  
Keyword(s):  
Ribosomal Rna ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Growth Defect ◽  
Rrna Processing ◽  
Ribosomal Subunits ◽  
Comprehensive Picture ◽  
Severe Growth Defect ◽  
H Protein ◽  
Severe Growth

AbstractThe biosynthesis of ribosomes is a complex cellular process involving ribosomal RNA, ribosomal proteins and several further trans-acting factors. DExD/H box proteins constitute the largest family of trans-acting protein factors involved in this process. Several members of this protein family have been directly implicated in ribosome biogenesis in yeast. In trypanosomes, ribosome biogenesis differs in several features from the process described in yeast. Here, we have identified the DExD/H box helicase Hel66 as being involved in ribosome biogenesis. The protein is unique to Kinetoplastida, localises to the nucleolus and its depletion via RNAi caused a severe growth defect. Loss of the protein resulted in a decrease of global translation and accumulation of rRNA processing intermediates for both the small and large ribosomal subunits. Only a few factors involved in trypanosome rRNA biogenesis have been described so far and our findings contribute to gaining a more comprehensive picture of this essential process.

scholarly journals A novel stress response pathway regulates rRNA biogenesis

2020 ◽  
Author(s):  
Witold Szaflarski ◽  
Mateusz Sowiński ◽  
Marta Leśniczak ◽  
Sandeep Ojha ◽  
Anaïs Aulas ◽  
...  
Keyword(s):  
Stress Response ◽  
Ribosomal Protein ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Protein Translation ◽  
Rrna Processing ◽  
Stress Response Pathway ◽  
Cellular Translation ◽  
Response To Stress ◽  
Ribosomal Protein Synthesis

ABSTRACTProduction of ribosomes is an energy-intensive process owing to the intricacy of these massive macromolecular machines. Each human ribosome contains 80 ribosomal proteins and four non-coding RNAs. Accurate assembly requires precise regulation of protein and RNA subunits. In response to stress, the integrated stress response (ISR) rapidly inhibits global translation. How rRNA is coordinately regulated with the rapid inhibition of ribosomal protein synthesis is not known. Here we show that stress specifically inhibits the first step of rRNA processing. Unprocessed rRNA is stored within the nucleolus, and, when stress resolves, it re-enters the ribosome biogenesis pathway. Retention of unprocessed rRNA within the nucleolus aids in the maintenance of this organelle. This response is independent of the ISR or inhibition of cellular translation but represents an independent stress-response pathway that we term Ribosome Biogenesis Stress Response (RiBiSR). Failure to coordinately regulate ribosomal protein translation and rRNA production results in nucleolar fragmentation. Our study unveils a novel stress response pathway that aims at conserving energy, preserving the nucleolus, and prevents further stress by regulation of rRNA processing.

scholarly journals Intersection of the Kap123p-Mediated Nuclear Import and Ribosome Export Pathways

2003 ◽  
Vol 23 (6) ◽  
pp. 2042-2054 ◽  
Author(s):  
Y. Sydorskyy ◽  
D. J. Dilworth ◽  
E. C. Yi ◽  
D. R. Goodlett ◽  
R. W. Wozniak ◽  
...  
Keyword(s):  
Nuclear Import ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Genetic Interaction ◽  
Ribosomal Subunit ◽  
Nucleocytoplasmic Transport ◽  
Rrna Processing ◽  
Ribosomal Subunits ◽  
Double Mutant Strain ◽  
Ribosome Export

ABSTRACT Kap123p is a yeast β-karyopherin that imports ribosomal proteins into the nucleus prior to their assembly into preribosomal particles. Surprisingly, Kap123p is not essential for growth, under normal conditions. To further explore the role of Kap123p in nucleocytoplasmic transport and ribosome biogenesis, we performed a synthetic fitness screen designed to identify genes that interact with KAP123. Through this analysis we have identified three other karyopherins, Pse1p/Kap121p, Sxm1p/Kap108p, and Nmd5p/Kap119p. We propose that, in the absence of Kap123p, these karyopherins are able to supplant Kap123p's role in import. In addition to the karyopherins, we identified Rai1p, a protein previously implicated in rRNA processing. Rai1p is also not essential, but deletion of the RAI1 gene is deleterious to cell growth and causes defects in rRNA processing, which leads to an imbalance of the 60S/40S ratio and the accumulation of halfmers, 40S subunits assembled on polysomes that are unable to form functional ribosomes. Rai1p localizes predominantly to the nucleus, where it physically interacts with Rat1p and pre-60S ribosomal subunits. Analysis of the rai1/kap123 double mutant strain suggests that the observed genetic interaction results from an inability to efficiently export pre-60S subunits from the nucleus, which arises from a combination of compromised Kap123p-mediated nuclear import of the essential 60S ribosomal subunit export factor, Nmd3p, and a ΔRAI1-induced decrease in the overall biogenesis efficiency.

Sign in / Sign up

Export Citation Format

Share Document