Roles and interactions of the specialized initiation factors <scp>EIF4E2</scp>, <scp>EIF4E5,</scp> and <scp>EIF4E6</scp> in <i>Trypanosoma brucei</i>: <scp>EIF4E2</scp> maintains the abundances of S‐phase <scp>mRNAs</scp>

Falk, Franziska; Palhares, Rafael Melo; Waithaka, Albina; Clayton, Christine

doi:10.1111/mmi.14978

Cited by 4 publications

(6 citation statements)

References 92 publications

(217 reference statements)

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“…This finding supports the idea that the C‐terminus extension in LeishIF4E2 can promote its binding to SLBP2. In accordance, it was previously reported that the T.brucei EIF4E2 was associated with SLBP2 28,29 …”

Section: Resultssupporting

confidence: 91%

“…The human ribosomal protein SA (RPSA), also known as Laminin Receptor 1 (LamR1), is part of the ribosomal machinery and also acts as a membrane receptor for laminin, growth factors, prions, and certain pathogens 44,45 . We identified only one protein in our proteomic data that its transcript was downregulated in T. brucei [EIF4E2 KO as compared to EIF4E2 add back, Tb927.9.2800 29 ]; the methylated‐DNA‐[protein]‐cysteine S‐methyltransferase (LmxM.26.1800) was downregulated in Leishmania , with an FC of log 2 ~ −2.2, and a p ‐value of .008.…”

Section: Resultsmentioning

confidence: 99%

“…EIF4E2 was reported to strongly interact with several S‐phase mRNAs; the level of these transcripts decreased in EIF4E2 knock‐out cells. However, while Yeast 2‐hybrid assays demonstrated a direct interaction between PUF9 and SLBP2, PUF9 was not detected in EIF4E2 pull‐downs 29 …”

Section: Introductionmentioning

confidence: 88%

“…However, while Yeast 2-hybrid assays demonstrated a direct interaction between PUF9 and SLBP2, PUF9 was not detected in EIF4E2 pull-downs. 29 Structure prediction and sequence alignment of LeishIF4E2 with the human eIF4E revealed the presence of a C-terminal extension in LeishIF4E2 that was not observed in other LeishIF4E paralogs or in the human eIF4E. This extension was shown to interfere with the binding activity of LeishIF4E2 to m 7 GTP, using recombinant and transgenic proteins.…”

Section: Introductionmentioning

confidence: 92%

“…In accordance, it was previously reported that the T.brucei EIF4E2 was associated with SLBP2. 28,29 F I G U R E 4 Volcano plots of the LeishIF4E2 1-281 and LeishIF4E2 1-217 interactomes. Cells expressing the SBP-LeishIF4E2 1-281 (Full) and SBP-LeishIF4E2 1-217 (Short) were lysed, and the extracts were loaded over streptavidin-Sepharose beads.…”

Section: Leishif4e2 1-281 Preferentially Binds the Stem-loop Binding ...mentioning

confidence: 99%

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LeishIF4E2 is a cap‐binding protein that plays a role in Leishmania cell cycle progression

Baron,

Purushotham,

Pullaiahgari

et al. 2023

The FASEB Journal

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Leishmania encode six paralogs of the cap‐binding protein eIF4E and five eIF4G candidates, forming unique complexes. Two cap‐binding proteins, LeishIF4E1 and LeishIF4E2, do not bind any identified LeishIF4Gs, thus their roles are intriguing. Here, we combine structural prediction, proteomic analysis, and interaction assays to shed light on LeishIF4E2 function. A nonconserved C‐terminal extension was identified through structure prediction and sequence alignment. m7GTP‐binding assays involving both recombinant and transgenic LeishIF4E2 with and without the C‐terminal extension revealed that this extension functions as a regulatory gate, modulating the cap‐binding activity of LeishIF4E2. The interactomes of the two LeishIF4E2 versions were investigated, highlighting the role of the C‐terminal extension in binding to SLBP2. SLBP2 is known to interact with a stem‐loop structure in the 3′ UTRs of histone mRNAs. Consistent with the predicted inhibitory effect of SLBP2 on histone expression in Xenopus laevis, a hemizygous deletion mutant of LeishIF4E2, exhibited an upregulation of several histones. We therefore propose that LeishIF4E2 is involved in histone expression, possibly through its interaction between SLBP2 and LeishIF4E2, thus affecting cell cycle progression. In addition, cell synchronization showed that LeishIF4E2 expression decreased during the S‐phase, when histones are known to be synthesized. Previous studies in T. brucei also highlighted an association between TbEIF4E2 and SLBP2, and further reported on an interaction between TbIF4E2 and S‐phase‐abundant mRNAs. Our results show that overexpression of LeishIF4E2 correlates with upregulation of cell cycle and chromosome maintenance proteins. Along with its effect on histone expression, we propose that LeishIF4E2 is involved in cell cycle progression.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 92%

Section: Leishif4e2 1-281 Preferentially Binds the Stem-loop Binding ...mentioning

confidence: 99%

See 3 more Smart Citations

LeishIF4E2 is a cap‐binding protein that plays a role in Leishmania cell cycle progression

Baron,

Purushotham,

Pullaiahgari

et al. 2023

The FASEB Journal

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Structural analysis of the Trypanosoma brucei EIF4E6/EIF4G5 complex reveals details of the interaction between unusual eIF4F subunits

Penteado,

da Silva,

Moura

et al. 2024

Sci Rep

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Recognition of the mRNA 5′ end is a critical step needed for translation initiation. This step is performed by the cap binding protein eIF4E, which joins the larger eIF4G subunit to form the eIF4F complex. Trypanosomatids have a minimum of five different eIF4F-like complexes formed through specific but not well-defined interactions between four different eIF4E and five eIF4G homologues. The EIF4E6/EIF4G5 complex has been linked with the stage-specific translation of mRNAs encoding the major Trypanosoma brucei virulence factors. Here, to better define the molecular basis for the TbEIF4E6/TbEIF4G5 interaction, we describe the identification of the peptide interacting with TbEIF4E6 in the region comprising residues 79–166 of TbEIF4G5. The TbEIF4E6-TbEIF4G5_79-116 complex reconstituted with recombinant proteins is highly stable even in the absence of cap-4. The crystal structure of the complex was subsequently solved, revealing extensive interacting surfaces. Comparative analyses highlight the conservation of the overall structural arrangement of different eIF4E/eIF4G complexes. However, highly different interacting surfaces are formed with distinct binding contacts occurring both in the canonical and noncanonical elements within eIF4G and the respective eIF4E counterpart. These specific pairs of complementary interacting surfaces are likely responsible for the selective association needed for the formation of distinct eIF4F complexes in trypanosomatids.

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Trypanosoma cruzi eIF4E3- and eIF4E4-containing complexes bind different mRNAs and may sequester inactive mRNAs during nutritional stress

Gabiatti,

Freire,

Ferreira da Costa

et al. 2024

Nucleic Acids Research

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Many eIF4F and poly(A)-binding protein (PABP) paralogues are found in trypanosomes: six eIF4E, five eIF4G, one eIF4A and two PABPs. They are expressed simultaneously and assemble into different complexes, contrasting the situation in metazoans that use distinct complexes in different cell types/developmental stages. Each eIF4F complex has its own proteins, messenger RNAs (mRNAs) and, consequently, a distinct function. We set out to study the function and regulation of the two eIF4F complexes of the parasite Trypanosoma cruzi and identified the associated proteins and mRNAs of eIF4E3 and eIF4E4 in cells in exponential growth and in nutritional stress, an inducer of differentiation to an infective stage. Upon stress, eIF4G and PABP remain associated with the eIF4E, but the associations with other 43S pre-initiation factors decrease, indicating ribosome attachment is impaired. Most eIF4E3-associated mRNAs encode for proteins involved in anabolic metabolism, while eIF4E4 associate with mRNAs encoding ribosomal proteins as in Trypanosoma brucei. Interestingly, for both eIF4E3/4, more mRNAs were associated in stressed cells than in non-stressed cells, even though these have lower translational efficiencies in stress. In summary, trypanosomes have two co-existing eIF4F complexes associating to different mRNAs, but not stress/differentiation-associated mRNAs. Under stress, both complexes exit translation but remain bound to their mRNA targets

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Roles and interactions of the specialized initiation factors EIF4E2, EIF4E5, and EIF4E6 in Trypanosoma brucei: EIF4E2 maintains the abundances of S‐phase mRNAs

Cited by 4 publications

References 92 publications

LeishIF4E2 is a cap‐binding protein that plays a role in Leishmania cell cycle progression

LeishIF4E2 is a cap‐binding protein that plays a role in Leishmania cell cycle progression

Structural analysis of the Trypanosoma brucei EIF4E6/EIF4G5 complex reveals details of the interaction between unusual eIF4F subunits

Trypanosoma cruzi eIF4E3- and eIF4E4-containing complexes bind different mRNAs and may sequester inactive mRNAs during nutritional stress

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