An essential role of KREPB4 in RNA editing and structural integrity of the editosome in Trypanosoma brucei

ABSTRACT RNA editing produces mature mitochondrial mRNAs in trypanosomatids by the insertion and deletion of uridylates. It is catalyzed by a multiprotein complex, the editosome. We identified TbMP44 among the components of enriched editosomes by a combination of mass spectrometry and DNA sequence database analysis. Inactivation of an ectopic TbMP44 allele in cells in which the endogenous alleles were disrupted abolished RNA editing, inhibited cell growth, and was eventually lethal to bloodstream form trypanosomes. Loss of TbMP44 mRNA was followed initially by a reduction in the editosome sedimentation coefficient and then by the absence of other editosome proteins despite the presence of the mRNA. Reactivation of TbMP44 gene expression resulted in the resumption of cell growth and the reappearance of editosomes. These data indicate that TbMP44 is a component of the editosome that is essential for editing and critical for the structural integrity of the editosome.

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The essential role of AMPA receptor GluR2 subunit RNA editing in the normal and diseased brain

Frontiers in Molecular Neuroscience ◽

10.3389/fnmol.2012.00034 ◽

2012 ◽

Vol 5 ◽

Cited By ~ 58

Author(s):

Amanda Wright ◽

Bryce Vissel

Keyword(s):

Rna Editing ◽

Ampa Receptor ◽

Essential Role

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An essential role of RNA editing enzyme ADAR1 in mouse skin

Journal of Dermatological Science ◽

10.1016/j.jdermsci.2011.06.013 ◽

2011 ◽

Vol 64 (1) ◽

pp. 70-72 ◽

Cited By ~ 12

Author(s):

Rohit Sharma ◽

Yujuan Wang ◽

Pei Zhou ◽

Richard A. Steinman ◽

Qingde Wang

Keyword(s):

Rna Editing ◽

Essential Role ◽

Mouse Skin ◽

Editing Enzyme

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Essential role of structural integrity and firm attachment of surface-anchored epidermal growth factor in adherent culture of neural stem cells

Biomaterials ◽

10.1016/j.biomaterials.2008.07.048 ◽

2008 ◽

Vol 29 (33) ◽

pp. 4403-4408 ◽

Cited By ~ 20

Author(s):

Tadashi Nakaji-Hirabayashi ◽

Koichi Kato ◽

Hiroo Iwata

Keyword(s):

Stem Cells ◽

Growth Factor ◽

Epidermal Growth Factor ◽

Neural Stem Cells ◽

Essential Role ◽

Structural Integrity ◽

Adherent Culture ◽

Epidermal Growth

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Sulfonated inhibitors of the RNA editing ligases validate the essential role of the MRP1/2 proteins in kinetoplastid RNA editing

RNA ◽

10.1261/rna.075598.120 ◽

2020 ◽

Vol 26 (7) ◽

pp. 827-835

Author(s):

Vaibhav Mehta ◽

Houtan Moshiri ◽

Akshaya Srikanth ◽

Smriti Kala ◽

Julius Lukeš ◽

...

Keyword(s):

Rna Editing ◽

Essential Role

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BS8 Essential role of endothelial ADAR1 RNA editing in vascular integrity

10.1136/heartjnl-2019-bcs.172 ◽

2019 ◽

Author(s):

Simon Tual-Chalot ◽

Francesca Bonini ◽

Nikolaos Vlachogiannis ◽

Anuradha Doddaballapur ◽

Kerida Shook ◽

...

Keyword(s):

Rna Editing ◽

Essential Role ◽

Vascular Integrity

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In Trypanosoma brucei RNA Editing, Band II Enables Recognition Specifically at Each Step of the U Insertion Cycle

Molecular and Cellular Biology ◽

10.1128/mcb.25.7.2785-2794.2005 ◽

2005 ◽

Vol 25 (7) ◽

pp. 2785-2794 ◽

Cited By ~ 8

Author(s):

Julie A. Law ◽

Catherine E. Huang ◽

Sean F. O'Hearn ◽

Barbara Sollner-Webb

Keyword(s):

Rna Interference ◽

Trypanosoma Brucei ◽

Rna Editing ◽

Cell Lines ◽

Protein Recognition ◽

Essential Nature ◽

Insertion And Deletion ◽

Insertion Sites

ABSTRACT Trypanosome RNA editing is the posttranscriptional insertion and deletion of uridylate (U) residues, often to a massive extent, through cycles of cleavage, U addition or U removal, and ligation. These editing cycles are catalyzed by a complex that we purified to seven major proteins (bands I through VII). Here we analyze the role of band II using extracts of clonal band II RNA interference (RNAi) cell lines prepared by a rapid protocol that enables retention of activities that are lost during traditional extract preparation. By individually scoring each step of editing, we show that band II is critical for all steps of U insertion but is not important for any of the steps of U deletion or for their coordination into the U deletion cycle. This specificity supports the long- standing model that U-insertional and U-deletional activities are separated within the editing complex. Furthermore, by assaying the basic activities of the enzymes that catalyze the steps of U insertion, independent of their action in editing, we show that band II is not any of those enzymes. Rather, band II enables endonuclease action at authentic U insertion sites, terminal-uridylyl-transferase (TUTase) action at cleaved U insertion sites, and U-insertion-specific ligase (band V/IREL) action in the editing complex. Thus, band II facilitates each step of U insertion by providing proper RNA and/or protein recognition. We propose that band II (TbMP81) be called IRER, indicating its essential nature in U-insertional RNA editing recognition.

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The Centriole Cartwheel Protein SAS-6 in Trypanosoma brucei Is Required for Probasal Body Biogenesis and Flagellum Assembly

Eukaryotic Cell ◽

10.1128/ec.00083-15 ◽

2015 ◽

Vol 14 (9) ◽

pp. 898-907 ◽

Cited By ~ 19

Author(s):

Huiqing Hu ◽

Yi Liu ◽

Qing Zhou ◽

Sara Siegel ◽

Ziyin Li

Keyword(s):

Cell Cycle ◽

Rna Interference ◽

Trypanosoma Brucei ◽

Basal Body ◽

Essential Role ◽

Microtubule Organizing Center ◽

Content Type ◽

Evolutionarily Conserved ◽

Organizing Center

ABSTRACT The centriole in eukaryotes functions as the cell's microtubule-organizing center (MTOC) to nucleate spindle assembly, and its biogenesis requires an evolutionarily conserved protein, SAS-6, which assembles the centriole cartwheel. Trypanosoma brucei , an early branching protozoan, possesses the basal body as its MTOC to nucleate flagellum biogenesis. However, little is known about the components of the basal body and their roles in basal body biogenesis and flagellum assembly. Here, we report that the T. brucei SAS-6 homolog, TbSAS-6, is localized to the mature basal body and the probasal body throughout the cell cycle. RNA interference (RNAi) of TbSAS-6 inhibited probasal body biogenesis, compromised flagellum assembly, and caused cytokinesis arrest. Surprisingly, overexpression of TbSAS-6 in T. brucei also impaired probasal body duplication and flagellum assembly, contrary to SAS-6 overexpression in humans, which produces supernumerary centrioles. Furthermore, we showed that depletion of T. brucei Polo-like kinase, TbPLK, or inhibition of TbPLK activity did not abolish TbSAS-6 localization to the basal body, in contrast to the essential role of Polo-like kinase in recruiting SAS-6 to centrioles in animals. Altogether, these results identified the essential role of TbSAS-6 in probasal body biogenesis and flagellum assembly and suggest the presence of a TbPLK-independent pathway governing basal body duplication in T. brucei .

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Depletion of the thioredoxin homologue tryparedoxin impairs antioxidative defence in African trypanosomes

Biochemical Journal ◽

10.1042/bj20061341 ◽

2007 ◽

Vol 402 (1) ◽

pp. 43-49 ◽

Cited By ~ 69

Author(s):

Marcelo A. Comini ◽

R. Luise Krauth-Siegel ◽

Leopold Flohé

Keyword(s):

Oxidative Stress ◽

Rna Interference ◽

Trypanosoma Brucei ◽

Growth Phase ◽

Essential Role ◽

Biological Significance ◽

Tsetse Fly ◽

African Trypanosomes ◽

Antioxidative Defence

In trypanosomes, the thioredoxin-type protein TXN (tryparedoxin) is a multi-purpose oxidoreductase that is involved in the detoxification of hydroperoxides, the synthesis of DNA precursors and the replication of the kinetoplastid DNA. African trypanosomes possess two isoforms that are localized in the cytosol and in the mitochondrion of the parasites respectively. Here we report on the biological significance of the cTXN (cytosolic TXN) of Trypanosoma brucei for hydroperoxide detoxification. Depending on the growth phase, the concentration of the protein is 3–7-fold higher in the parasite form infecting mammals (50–100 μM) than in the form hosted by the tsetse fly (7–34 μM). Depletion of the mRNA in bloodstream trypanosomes by RNA interference revealed the indispensability of the protein. Proliferation and viability of cultured trypanosomes were impaired when TXN was lowered to 1 μM for more than 48 h. Although the levels of glutathione, glutathionylspermidine and trypanothione were increased 2–3.5-fold, the sensitivity against exogenously generated H2O2 was significantly enhanced. The results prove the essential role of the cTXN and its pivotal function in the parasite defence against oxidative stress.

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