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Deciphering the mechanistic effects of eIF4E phosphorylation on mRNA-cap recognition.

ABSTRACT: The mRNA cap-binding oncoprotein "eIF4E" is phosphorylated at residue S209 by Mnk kinases, and is closely associated with tumor development and progression. Despite being well-established, mechanistic details at the molecular level of mRNA recognition by eIF4E due to phosphorylation have not been clearly elucidated. We investigated this through molecular modeling and simulations of the S209 phosphorylated derivative of eIF4E and explored the associated implication on the binding of the different variants of mRNA-cap analogs. A key feature that emerges as a result of eIF4E phosphorylation is a salt-bridge network between the phosphorylated S209 (pS209) and a specific pair of lysine residues (K159 and K162) within the cap-binding interface on eIF4E. This interaction linkage stabilizes the otherwise dynamic C-terminal region of the protein, resulting in the attenuation of the overall plasticity and accessibility of the binding pocket. The pS209-K159 salt-bridge also results in an energetically less favorable environment for the bound mRNA-cap primarily due to electrostatic repulsion between the negative potentials from the phosphates in the cap and those appearing as a result of phosphorylation of S209. These observations collectively imply that the binding of the mRNA-cap will be adversely affected in the phosphorylated derivative of eIF4E. We propose a mechanistic model highlighting the role of eIF4E phosphorylation as a regulatory tool in modulating eIF4E: mRNA-cap recognition and its potential impact on translation initiation.

SUBMITTER: Lama D

PROVIDER: S-EPMC7255503 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Phosphorylation of the mRNA cap-binding protein eIF4E and cancer.

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| S-EPMC8049097 | biostudies-literature

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Specificity of recognition of mRNA 5' cap by human nuclear cap-binding complex.

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Structural basis of mRNA-cap recognition by Dcp1-Dcp2.

Project description:Removal of the 5' cap on mRNA by the decapping enzyme Dcp2 is a critical step in 5'-to-3' mRNA decay. Understanding the structural basis of Dcp2 activity has been a challenge because Dcp2 is dynamic and has weak affinity for the cap substrate. Here we present a 2.6-Å-resolution crystal structure of a heterotrimer of fission yeast Dcp2, its essential activator Dcp1, and the human NMD cofactor PNRC2, in complex with a tight-binding cap analog. Cap binding is accompanied by a conformational change in Dcp2, thereby forming a composite nucleotide-binding site comprising conserved residues in the catalytic and regulatory domains. Kinetic analysis of PNRC2 revealed that a conserved short linear motif enhances both substrate affinity and the catalytic step of decapping. These findings explain why Dcp2 requires a conformational change for efficient catalysis and reveals that coactivators promote RNA binding and the catalytic step of decapping, possibly through different conformational states.

| S-EPMC5113729 | biostudies-literature

The human Ago2 MC region does not contain an eIF4E-like mRNA cap binding motif.

Project description:BackgroundArgonaute (Ago) proteins interact with small regulatory RNAs to mediate gene regulatory pathways. A recent report by Kiriakidou et al. 1 describes an MC sequence region identified in Ago2 that displays similarity to the cap-binding motif in translation initiation factor 4E (eIF4E). In a cap-bound eIF4E structure, two important aromatic residues of the motif stack on either side of a 7-methylguanosine 5'-triphosphate (m7Gppp) base. The corresponding Ago2 aromatic residues (F450 and F505) were hypothesized to perform the same cap-binding function. However, the detected similarity between the MC sequence and the eIF4E cap-binding motif was questionable.ResultsA number of sequence-based and structure-based bioinformatics methods reveal the reported similarity between the Ago2 MC sequence region and the eIF4E cap-binding motif to be spurious. Alternatively, the MC sequence region is confidently assigned to the N-terminus of the Ago piwi module, within the mid domain of experimentally determined prokaryotic Ago structures. Confident mapping of the Ago2 MC sequence region to the piwi mid domain results in a homology-based structure model that positions the identified aromatic residues over 20 A apart, with one of the aromatic side chains (F450) contributing instead to the hydrophobic core of the domain.ConclusionCorrect functional prediction based on weak sequence similarity requires substantial evolutionary and structural support. The evolutionary context of the Ago mid domain suggested by multiple sequence alignment is limited to a conserved hydrophobicity profile required for the fold and a motif following the MC region that binds guide RNA. Mapping of the MC sequence to the mid domain structure reveals Ago2 aromatics that are incompatible with eIF4E-like mRNA cap-binding, yet display some limited local structure similarities that cause the chance sequence match to eIF4E.

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eIF4E Phosphorylation Influences Bdnf mRNA Translation in Mouse Dorsal Root Ganglion Neurons.

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| S-EPMC5808250 | biostudies-literature

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