scholarly journals Essential PBP1-associated proteins of Trypanosoma brucei

2020 ◽  
Author(s):  
L. Nascimento ◽  
M. Terrao ◽  
KK. Marucha ◽  
B. Liu ◽  
F. Egler ◽  
...  
Keyword(s):  
Trypanosoma Brucei ◽  
Ribosomal Proteins ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Low Complexity ◽  
Control Of Gene Expression ◽  
C Terminus ◽  
Associated Proteins ◽  
A Minor

AbstractControl of gene expression in kinetoplastids depends heavily on RNA-binding proteins that influence mRNA decay and translation. We previously showed that MKT1 interacts with PBP1, which in turn recruits LSM12 and poly(A) binding protein. MKT1 is recruited to mRNA by sequence-specific RNA-binding proteins, resulting in stabilisation of mRNA. We here show that PBP1, LSM12 and an additional 117-residue protein, XAC1 (Tb927.7.2780), are present in complexes that contain either MKT1 or MKT1L (Tb927.10.1490). All five proteins are present predominantly in the complexes, and there was evidence for a minor subset of complexes that contained both MKT1 and MKT1L. MKT1 appeared to be associated with many mRNAs, with the exception of those encoding ribosomal proteins. XAC1-containing complexes reproducibly contained RNA-binding proteins that were previously found associated with MKT1. In addition, however, XAC1- or MKT1-containing complexes specifically recruit one of the six translation initiation complexes, EIF4E6-EIF4G5; and yeast 2-hybrid assay results indicated that MKT1 interacts with EIF4G5. The C-terminus of MKT1L resembles MKT1: it contains MKT1 domains and a PIN domain that is probably not active as an endonuclease. MKT1L, however, also has an N-terminal extension with regions of low-complexity. Although MKT1L depletion inhibited cell proliferation, we found no evidence for specific interactions with RNA-binding proteins or mRNA. Deletion of the N-terminal extension, however, enabled MKT1L to interact with EIF4E6. We speculate that MKT1L may either enhance or inhibit the functions of MKT1-containing complexes.

scholarly journals The RNA-associated proteins MKT1 and MKT1L form alternative PBP1-containing complexes in Trypanosoma brucei

2020 ◽  
Vol 295 (32) ◽  
pp. 10940-10955 ◽  
Author(s):  
Larissa Melo do Nascimento ◽  
Monica Terrao ◽  
Kevin Kamanyi Marucha ◽  
Bin Liu ◽  
Franziska Egler ◽  
...  
Keyword(s):  
Ribosomal Proteins ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Low Complexity ◽  
Control Of Gene Expression ◽  
C Terminus ◽  
Associated Proteins ◽  
A Minor ◽  
Two Hybrid

Control of gene expression in kinetoplastids such as trypanosomes depends heavily on RNA-binding proteins that influence mRNA decay and translation. We previously showed that the trypanosome protein MKT1 forms a multicomponent protein complex: MKT1 interacts with PBP1, which in turn recruits LSM12 and poly(A)-binding protein. MKT1 is recruited to mRNAs by sequence-specific RNA-binding proteins, resulting in stabilization of the bound mRNA. We here show that PBP1, LSM12, and a 117-residue protein, XAC1 (Tb927.7.2780), are present in complexes that contain either MKT1 or an MKT1-like protein, MKT1L (Tb927.10.1490). All five proteins are present predominantly in the complexes, and we found evidence for a minor subset of complexes containing both MKT1 and MKT1L. XAC1-containing complexes reproducibly contained RNA-binding proteins that were previously found associated with MKT1. Moreover, XAC1- or MKT1-containing complexes specifically recruited one of the two poly(A)-binding proteins, PABP2, and one of the six cap-binding translation initiation complexes, EIF4E6–EIF4G5. Yeast two-hybrid assay results indicated that MKT1 directly interacts with EIF4G5. MKT1–PBP1 complexes can therefore interact with mRNAs via their poly(A) tails and caps, as well as through sequence-specific RNA-binding proteins. Correspondingly, MKT1 is associated with many mRNAs, although not with those encoding ribosomal proteins. Meanwhile, MKT1L resembles MKT1 at the C terminus but additionally features an N-terminal extension with low-complexity regions. Although MKT1L depletion inhibited cell proliferation, we found no evidence that it specifically interacts with RNA-binding proteins or mRNA. We speculate that MKT1L may compete with MKT1 for PBP1 binding and thereby modulate the function of MKT1-containing complexes.

scholarly journals The endoplasmic reticulum-associated mRNA-binding proteins ERBP1 and ERBP2 interact in bloodstream-form Trypanosoma brucei

2019 ◽  
Author(s):  
Kathrin Bajak ◽  
Kevin Leiss ◽  
Christine Clayton ◽  
Esteban Erben
Keyword(s):  
Endoplasmic Reticulum ◽  
Ribosomal Protein ◽  
Trypanosoma Brucei ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Bloodstream Form ◽  
Control Of Gene Expression ◽  
Mrna Binding Proteins ◽  
Mrna Binding

AbstractKinetoplastids rely heavily on post-transcriptional mechanisms for control of gene expression, and on RNA-binding proteins that regulate mRNA splicing, translation and decay. Trypanosoma brucei ERBP1 (Tb927.10.14150) and ERBP2 (Tb927.9.9550) were previously identified as mRNA binding proteins that lack canonical RNA-binding domains. We here show that ERBP1 is associated with the endoplasmic reticulum, like ERBP2, and that the two proteins interact in vivo. Loss of ERBP1 from bloodstream-form T. brucei initially resulted in a growth defect but proliferation was restored after more prolonged cultivation. Results from a pull-down of tagged ERBP1 suggest that it preferentially binds to ribosomal protein mRNAs. The ERBP1 sequence resembles that of Saccharomyces cerevisiae Bfr1, which also localises to the endoplasmic reticulum and binds to ribosomal protein mRNAs. However, unlike Bfr1, ERBP1 does not bind to mRNAs encoding secreted proteins, and it is also not recruited to stress granules after starvation.

scholarly journals The endoplasmic reticulum-associated mRNA-binding proteins ERBP1 and ERBP2 interact in bloodstream-form Trypanosoma brucei

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8388 ◽  
Author(s):  
Kathrin Bajak ◽  
Kevin Leiss ◽  
Christine E. Clayton ◽  
Esteban Erben
Keyword(s):  
Endoplasmic Reticulum ◽  
Ribosomal Protein ◽  
Trypanosoma Brucei ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Bloodstream Form ◽  
Control Of Gene Expression ◽  
Mrna Binding Proteins ◽  
Mrna Binding

Kinetoplastids rely heavily on post-transcriptional mechanisms for control of gene expression, and on RNA-binding proteins that regulate mRNA splicing, translation and decay. Trypanosoma brucei ERBP1 (Tb927.10.14150) and ERBP2 (Tb927.9.9550) were previously identified as mRNA binding proteins that lack canonical RNA-binding domains. We show here that ERBP1 is associated with the endoplasmic reticulum, like ERBP2, and that the two proteins interact in vivo. Loss of ERBP1 from bloodstream-form T. brucei initially resulted in a growth defect but proliferation was restored after more prolonged cultivation. Pull-down analysis of tagged ERBP1 suggests that it preferentially binds to ribosomal protein mRNAs. The ERBP1 sequence resembles that of Saccharomyces cerevisiae Bfr1, which also localises to the endoplasmic reticulum and binds to ribosomal protein mRNAs. However, unlike Bfr1, ERBP1 does not bind to mRNAs encoding secreted proteins, and it is also not recruited to stress granules after starvation.

scholarly journals Interactions of the Trypanosoma brucei brucei zinc-finger-domain protein ZC3H28

2021 ◽  
Author(s):  
Tania Bishola ◽  
Christine Clayton
Keyword(s):  
Trypanosoma Brucei ◽  
Zinc Finger ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Mrna Level ◽  
Critical Role ◽  
Regulation Of Gene Expression ◽  
Low Complexity ◽  
Mrna Binding

In Trypanosoma brucei and related Kinetoplastids, regulation of gene expression occurs mostly post-transcriptionally, and RNA-binding proteins play a critical role in the regulation of mRNA and protein abundance. Trypanosoma brucei ZC3H28 is a 114 KDa cytoplasmic mRNA-binding protein with a single C(x)7C(x)5C(x)sH zinc finger at the C-terminus and numerous proline-, histine- or glutamine-rich regions. We here show that N-terminally tagged ZC3H28 copurifies ribosomes, various RNA-binding proteins, and the translation initiation complex EIF4E4/EIF4G3. ZC3H28 is preferentially associated with long RNAs that have low complexity sequences in their 3'-untranslated regions. When tethered to a reporter mRNA, ZC3H28 increased the mRNA level without a corresponding increase in protein expression; this suggests that it stabilized the reporter but at the same time suppressed its translation. Indeed, there was a clear negative correlation between ZC3H28 mRNA binding and ribosome density. After ZC3H28 depletion, the relative levels of ribosomal protein mRNAs increased while levels of some long mRNAs decreased, but there is no overall correlation between binding and RNAi effects on mRNA abundance. We speculate that ZC3H28 might be implicated in stabilizing poorly-translated mRNAs.

scholarly journals RNA Binding Proteins and the Pathogenesis of Frontotemporal Lobar Degeneration

2019 ◽  
Vol 14 (1) ◽  
pp. 469-495 ◽  
Author(s):  
Jeffrey W. Hofmann ◽  
William W. Seeley ◽  
Eric J. Huang
Keyword(s):  
Frontotemporal Lobar Degeneration ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Low Complexity ◽  
Compelling Evidence ◽  
Abnormal Protein ◽  
Early Onset Dementia ◽  
Cellular Pathways ◽  
Liquid Liquid Phase Separation

Frontotemporal dementia is a group of early onset dementia syndromes linked to underlying frontotemporal lobar degeneration (FTLD) pathology that can be classified based on the formation of abnormal protein aggregates involving tau and two RNA binding proteins, TDP-43 and FUS. Although elucidation of the mechanisms leading to FTLD pathology is in progress, recent advances in genetics and neuropathology indicate that a majority of FTLD cases with proteinopathy involving RNA binding proteins show highly congruent genotype–phenotype correlations. Specifically, recent studies have uncovered the unique properties of the low-complexity domains in RNA binding proteins that can facilitate liquid–liquid phase separation in the formation of membraneless organelles. Furthermore, there is compelling evidence that mutations in FTLD genes lead to dysfunction in diverse cellular pathways that converge on the endolysosomal pathway, autophagy, and neuroinflammation. Together, these results provide key mechanistic insights into the pathogenesis and potential therapeutic targets of FTLD.

Post-transcriptional regulation in hematopoiesis: RNA binding proteins take control

2019 ◽  
Vol 97 (1) ◽  
pp. 10-20 ◽  
Author(s):  
Laura P.M.H. de Rooij ◽  
Derek C.H. Chan ◽  
Ava Keyvani Chahi ◽  
Kristin J. Hope
Keyword(s):  
Transcriptional Regulation ◽  
Stem Cell ◽  
Cell Fate ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Control Of Gene Expression ◽  
Hematopoietic Stem ◽  
Cell Fate Decisions ◽  
Post Transcriptional Regulation

Normal hematopoiesis is sustained through a carefully orchestrated balance between hematopoietic stem cell (HSC) self-renewal and differentiation. The functional importance of this axis is underscored by the severity of disease phenotypes initiated by abnormal HSC function, including myelodysplastic syndromes and hematopoietic malignancies. Major advances in the understanding of transcriptional regulation of primitive hematopoietic cells have been achieved; however, the post-transcriptional regulatory layer that may impinge on their behavior remains underexplored by comparison. Key players at this level include RNA-binding proteins (RBPs), which execute precise and highly coordinated control of gene expression through modulation of RNA properties that include its splicing, polyadenylation, localization, degradation, or translation. With the recent identification of RBPs having essential roles in regulating proliferation and cell fate decisions in other systems, there has been an increasing appreciation of the importance of post-transcriptional control at the stem cell level. Here we discuss our current understanding of RBP-driven post-transcriptional regulation in HSCs, its implications for normal, perturbed, and malignant hematopoiesis, and the most recent technological innovations aimed at RBP–RNA network characterization at the systems level. Emerging evidence highlights RBP-driven control as an underappreciated feature of primitive hematopoiesis, the greater understanding of which has important clinical implications.

scholarly journals RNA-binding proteins with prion-like domains in health and disease

2017 ◽  
Vol 474 (8) ◽  
pp. 1417-1438 ◽  
Author(s):  
Alice Ford Harrison ◽  
James Shorter
Keyword(s):  
Phase Transitions ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Low Complexity ◽  
Fused In Sarcoma ◽  
Heterogeneous Nuclear Ribonucleoproteins ◽  
Health And Disease ◽  
Lateral Sclerosis

Approximately 70 human RNA-binding proteins (RBPs) contain a prion-like domain (PrLD). PrLDs are low-complexity domains that possess a similar amino acid composition to prion domains in yeast, which enable several proteins, including Sup35 and Rnq1, to form infectious conformers, termed prions. In humans, PrLDs contribute to RBP function and enable RBPs to undergo liquid–liquid phase transitions that underlie the biogenesis of various membraneless organelles. However, this activity appears to render RBPs prone to misfolding and aggregation connected to neurodegenerative disease. Indeed, numerous RBPs with PrLDs, including TDP-43 (transactivation response element DNA-binding protein 43), FUS (fused in sarcoma), TAF15 (TATA-binding protein-associated factor 15), EWSR1 (Ewing sarcoma breakpoint region 1), and heterogeneous nuclear ribonucleoproteins A1 and A2 (hnRNPA1 and hnRNPA2), have now been connected via pathology and genetics to the etiology of several neurodegenerative diseases, including amyotrophic lateral sclerosis, frontotemporal dementia, and multisystem proteinopathy. Here, we review the physiological and pathological roles of the most prominent RBPs with PrLDs. We also highlight the potential of protein disaggregases, including Hsp104, as a therapeutic strategy to combat the aberrant phase transitions of RBPs with PrLDs that likely underpin neurodegeneration.

scholarly journals A potential role for a novel ZC3H5 complex in regulating mRNA translation in Trypanosoma brucei

2020 ◽  
Vol 295 (42) ◽  
pp. 14291-14304
Author(s):  
Kathrin Bajak ◽  
Kevin Leiss ◽  
Christine Clayton ◽  
Esteban Erben
Keyword(s):  
Gene Expression ◽  
Trypanosoma Brucei ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Affinity Purification ◽  
Critical Role ◽  
Rna Binding Protein ◽  
Mrna Translation

In Trypanosoma brucei and related kinetoplastids, gene expression regulation occurs mostly posttranscriptionally. Consequently, RNA-binding proteins play a critical role in the regulation of mRNA and protein abundance. Yet, the roles of many RNA-binding proteins are not understood. Our previous research identified the RNA-binding protein ZC3H5 as possibly involved in gene repression, but its role in controlling gene expression was unknown. We here show that ZC3H5 is an essential cytoplasmic RNA-binding protein. RNAi targeting ZC3H5 causes accumulation of precytokinetic cells followed by rapid cell death. Affinity purification and pairwise yeast two-hybrid analysis suggest that ZC3H5 forms a complex with three other proteins, encoded by genes Tb927.11.4900, Tb927.8.1500, and Tb927.7.3040. RNA immunoprecipitation revealed that ZC3H5 is preferentially associated with poorly translated, low-stability mRNAs, the 5′-untranslated regions and coding regions of which are enriched in the motif (U/A)UAG(U/A). As previously found in high-throughput analyses, artificial tethering of ZC3H5 to a reporter mRNA or other complex components repressed reporter expression. However, depletion of ZC3H5 in vivo caused only very minor decreases in a few targets, marked increases in the abundances of very stable mRNAs, an increase in monosomes at the expense of large polysomes, and appearance of “halfmer” disomes containing two 80S subunits and one 40S subunit. We speculate that the ZC3H5 complex might be implicated in quality control during the translation of suboptimal open reading frames.

238 RNA BINDING PROTEIN EXPRESSION IN CULTURED EARLY BOVINE EMBRYOS

2010 ◽  
Vol 22 (1) ◽  
pp. 277
Author(s):  
L. A. Favetta ◽  
E. Van de Laar ◽  
W. A. King ◽  
J. LaMarre
Keyword(s):  
Gene Expression ◽  
Protein Expression ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Bovine Embryo ◽  
Rt Pcr ◽  
Control Of Gene Expression ◽  
Morula Stage ◽  
Bovine Oocytes

The control of gene expression in the early embryo requires a highly regulated turnover of specific mRNA, particularly those of maternal origin, as the embryo becomes transcriptionally autonomous. In cattle, the period during which maternal transcripts persist can last 72 to 96 h or longer, suggesting a dynamic, regulated interplay between factors that protect transcripts before this point and those that subsequently facilitate decay. Some decay pathways for specific embryonic transcripts are now known, but many are not. In somatic cells, mRNA decay is often mediated by interactions between defined sequence elements (ARE) in the 3′ untranslated region of important target genes and specific RNA-binding proteins (AUBP) that promote or inhibit decay of the associated transcript. These have not been extensively characterized in embryos. We hypothesized that changes in the pattern of expression of one or several AUBP in the developing bovine embryo would support a role for these proteins in mRNA turnover and the control of gene expression. We, therefore, evaluated the expression of different AUBP (HuR, AUF1, TTP) in bovine oocytes and early embryos in vitro. Bovine oocytes obtained at slaughter were matured, fertilized, and cultured using standard protocols. Oocytes and embryos from different stages were either placed in Trizol for subsequent RNA isolation and RT-PCR analysis or fixed in 4% paraformaldehyde and subsequently processed for immunohistochemical detection of AUBP. Analysis by RT-PCR revealed that AUF1, an mRNA destabilizing protein, was expressed at all stages examined (immature oocyte, mature oocyte, 2 to 4 cells, 8 to 16 cells, morulae, and blastocyst) except in morulae. Another mRNA destabilizing protein, TTP, was expressed at the morula stage only. An mRNA stabilizing factor, HuR, was expressed at all stages except the morula. Immunohistochemical analysis revealed that the pattern of protein expression for AUF1 and TTP essentially mirrored that observed at the RNA level as detected by RT-PCR. Together, these results show that AUBP expression in the early bovine embryo is dynamic, with RNA-binding proteins present at all times during development and changes in expression evident at the morula stage. This suggests that modification of presynthesized (i.e. maternal) AUBP is likely to control mRNA decay during the maternal to embryonic transition (8-cell stage) and that the expression of TTP at the morula stage might mark the onset of embryonic control of mRNA stability. Research was supported by NSERC, OMAFRA, and the Canada Research Chairs Program.

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