m7G cap-eIF4E interaction stimulates polysome formation by enhancing first-round initiation kinetics

Translation in eukaryotic cells occurs predominantly through a 7-methylguanosine (m7G) cap-dependent mechanism. m7G cap interactions with eukaryotic initiation factor 4E (eIF4E) facilitates 43S recruitment to the mRNA 5' end and enhances the translation efficiency of mRNA. However, it remains poorly understood how m7G cap-eIF4E interactions affect polysome formation kinetics. Here, we examine the role of the m7G cap in polysome formation by utilizing a single-molecule approach to track individual ribosomes during active translation. Translation was monitored in wheat germ extract with capped and uncapped synthetic mRNAs and in HeLa extract with purified human eIF4E titration. The presence of the m7G cap and the supplementation of eIF4E to eIF4E-deficient extract enhanced the kinetics of the first initiation event of polysomes. Subsequent to the first initiation event, efficient polysome-forming initiation events occurred independent of mRNA m7G capping status and eIF4E concentration. Our results indicate that m7G cap-eIF4E interactions in wheat germ and HeLa extracts promote polysome formation by enhancing first-round initiation kinetics. The dynamics of individual translation events on polysomal mRNAs suggest that first-round initiation events activate mRNAs for efficient subsequent rounds of polysome-forming initiation.

Download Full-text

Kinetics of ribosome dissociation and subunit association. The role of initiation factor IF3 as an effector.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)86287-7 ◽

1980 ◽

Vol 255 (1) ◽

pp. 225-229

Author(s):

D.J. Goss ◽

L.J. Parkhurst ◽

A.J. Wahba

Keyword(s):

Initiation Factor ◽

Kinetics Of

Download Full-text

Dynamics of Tpm1.8 domains on actin filaments with single molecule resolution

10.1101/2020.06.15.152033 ◽

2020 ◽

Cited By ~ 1

Author(s):

Ilina Bareja ◽

Hugo Wioland ◽

Miro Janco ◽

Philip R. Nicovich ◽

Antoine Jégou ◽

...

Keyword(s):

Actin Filament ◽

Single Molecule ◽

Actin Filaments ◽

High Probability ◽

Actin Binding ◽

Single Molecule Level ◽

Filament Dynamics ◽

Kinetics Of ◽

Insight Into

ABSTRACTTropomyosins regulate dynamics and functions of the actin cytoskeleton by forming long chains along the two strands of actin filaments that act as gatekeepers for the binding of other actin-binding proteins. The fundamental molecular interactions underlying the binding of tropomyosin to actin are still poorly understood. Using microfluidics and fluorescence microscopy, we observed the binding of fluorescently labelled tropomyosin isoform Tpm1.8 to unlabelled actin filaments in real time. This approach in conjunction with mathematical modeling enabled us to quantify the nucleation, assembly and disassembly kinetics of Tpm1.8 on single filaments and at the single molecule level. Our analysis suggests that Tpm1.8 decorates the two strands of the actin filament independently. Nucleation of a growing tropomyosin domain proceeds with high probability as soon as the first Tpm1.8 molecule is stabilised by the addition of a second molecule, ultimately leading to full decoration of the actin filament. In addition, Tpm1.8 domains are asymmetrical, with enhanced dynamics at the edge oriented towards the barbed end of the actin filament. The complete description of Tpm1.8 kinetics on actin filaments presented here provides molecular insight into actin-tropomyosin filament formation and the role of tropomyosins in regulating actin filament dynamics.

Download Full-text

Single-Molecule Kinetics of Styrene Hydrogenation on Silica-Supported Vanadium: The Role of Disorder for Single-Atom Catalysts

The Journal of Physical Chemistry C ◽

10.1021/acs.jpcc.1c04759 ◽

2021 ◽

Vol 125 (37) ◽

pp. 20286-20300

Author(s):

Robert H. Wells ◽

Suming An ◽

Prajay Patel ◽

Cong Liu ◽

Rex T. Skodje

Keyword(s):

Single Molecule ◽

Single Atom ◽

Styrene Hydrogenation ◽

Kinetics Of

Download Full-text

Deeping in the Role of the MAP-Kinases Interacting Kinases (MNKs) in Cancer

International Journal of Molecular Sciences ◽

10.3390/ijms21082967 ◽

2020 ◽

Vol 21 (8) ◽

pp. 2967

Author(s):

Celia Pinto-Díez ◽

Raquel Ferreras-Martín ◽

Rebeca Carrión-Marchante ◽

Víctor M. González ◽

María Elena Martín

Keyword(s):

Map Kinases ◽

Mitogen Activated Protein Kinase ◽

Initiation Factor ◽

Eukaryotic Initiation Factor 4E ◽

Polypyrimidine Tract Binding Protein ◽

Hematological Cancers ◽

Mitogen Activated Protein ◽

Specific Proteins ◽

Nuclear Ribonucleoprotein

The mitogen-activated protein kinase (MAPK)-interacting kinases (MNKs) are involved in oncogenic transformation and can promote metastasis and tumor progression. In human cells, there are four MNKs isoforms (MNK1a/b and MNK2a/b), derived from two genes by alternative splicing. These kinases play an important role controlling the expression of specific proteins involved in cell cycle, cell survival and cell motility via eukaryotic initiation factor 4E (eIF4E) regulation, but also through other substrates such as heterogeneous nuclear ribonucleoprotein A1, polypyrimidine tract-binding protein-associated splicing factor and Sprouty 2. In this review, we provide an overview of the role of MNK in human cancers, describing the studies conducted to date to elucidate the mechanism involved in the action of MNKs, as well as the development of MNK inhibitors in different hematological cancers and solid tumors.

Download Full-text

Poly(A)‐Binding Protein Affects the Kinetics of Tobacco Etch Virus Pseudoknot RNA Binding to Wheat germ Translation Initiation Factor eIF4F

The FASEB Journal ◽

10.1096/fasebj.22.1_supplement.998.1 ◽

2008 ◽

Vol 22 (S1) ◽

Author(s):

Mateen A Khan ◽

Daniel R Gallie ◽

Dixie J Goss

Keyword(s):

Translation Initiation ◽

Wheat Germ ◽

Rna Binding ◽

Binding Protein ◽

Tobacco Etch Virus ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Kinetics Of

Download Full-text

A Blood Pact: the Significance and Implications of eIF4E on Lymphocytic Leukemia

Physiological Research ◽

10.33549/physiolres.933696 ◽

2018 ◽

pp. 363-382

Author(s):

V. VENTURI ◽

T. MASEK ◽

M. POSPISEK

Keyword(s):

Translational Control ◽

Lymphoblastic Leukemia ◽

Lymphocytic Leukemia ◽

Initiation Factor ◽

Oncogenic Signaling ◽

Translation Factor ◽

Eukaryotic Initiation Factor 4E ◽

Biological Circuits ◽

Oncogenic Signaling Pathways

Elevated levels of eukaryotic initiation factor 4E (eIF4E) are implicated in neoplasia, with cumulative evidence pointing to its role in the etiopathogenesis of hematological diseases. As a node of convergence for several oncogenic signaling pathways, eIF4E has attracted a great deal of interest from biologists and clinicians whose efforts have been targeting this translation factor and its biological circuits in the battle against leukemia. The role of eIF4E in myeloid leukemia has been ascertained and drugs targeting its functions have found their place in clinical trials. Little is known, however, about the pertinence of eIF4E to the biology of lymphocytic leukemia and a paucity of literature is available in this regard that prospectively evaluates the topic to guide practice in hematological cancer. A comprehensive analysis on the significance of eIF4E translation factor in the clinical picture of leukemia arises, therefore, as a compelling need. This review presents aspects of eIF4E involvement in the realm of the lymphoblastic leukemia status; translational control of immunological function via eIF4E and the state-of-the-art in drugs will also be outlined.

Download Full-text