Leucine-zipper motif is responsible for self-association of translation elongation factor 1Bβ

Abstract

Translation elongation factor 1Bβ (eEF1Bβ) is a metazoan-specific protein catalyzing the guanine nucleotide exchange on translation elongation factor 1A (eEF1A). eEF1Bβ was reported to form oligomers. Aim. To define the structural region of human eEF1Bβ that mediates its self-association. In addition, the various truncated forms of this protein were tested in the guanine nucleotide exchange assay with two isoforms of mammalian eEF1A. Methods. The truncated forms of eEF1Bβ were generated by PCR, cloned, expressed in Escherichia coli and purified to homogeneity. Their apparent molecular masses were determined by analytical gel filtration and their guanine nucleotide exchange activities were assessed by filter binding assay. Results. Complete deletion of the N-terminal domain of eEF1Bβ does not affect its oligomerization propensity while deletion of the leucine-zipper motif drastically decreases the apparent molecular mass of the truncated form compared to the full-length protein. Also, the leucine-zipper motif of eEF1Bβ fused to glutathione S-transferase causes oligomerization of the chimeric protein. It was demonstrated that all N-terminally truncated forms of eEF1Bβ displayed similar catalytic activity to that of the full-length protein. Weak inhibitory effect on the catalytic activity was observed only for the truncated form with partially deleted central acidic region. Conclusions. The leucine-zipper motif facilitates oligomerization of recombinant eEF1Bβ. Stepwise deletion of the eEF1Bβ N-terminal domain does not significantly affect the guanine nucleotide exchange activity of the truncated proteins. K e y w o r d s: translation elongation factor 1, guanine nucleotide exchange, protein structural domains.

Non-translational Connections of eEF1B in the Cytoplasm and Nucleus of Cancer Cells

“…eEF1Bβ and eEF1Bα have similar domain structure. The C-terminal part of eEF1Bβ is highly homologous to the C-terminal domain of eEF1Bα, while the N-terminal fragment has the unique amino acid sequence, a part of which is a leucine-zipper structure responsible for oligomerization of eEF1Bβ (Bondarchuk et al, 2016). The very N-terminal fragment (1-77 amino acid residues) binds eEF1Bγ and, possibly, other proteins (Bondarchuk et al, 2019), however, we cannot exclude at present that the remaining part of the eEF1Bβ N-terminal domain is also involved in eEF1Bγ binding.…”

Non-canonical interactions of the β subunit of the translation elongation complex eEF1B and analysis of their possible functional role

“…In the case this interaction is confirmed by other experimental means, it may shed a light on the novel structural feature of the organization of translation compartment in human cells. Interestingly, the translationrelated subcluster comprised both several tRNA synthetases (IARS, RARS, MARS) and eEF1Bβ itself, the latter observation favors a possibility of forming eEF1Bβ oligomers [18]. Peculiar is the existence of a direct contact of eEF1Bβ with the protein arginine methyltransferase 1 (PRMT1) (Fig.…”

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“…One may suggest that cyto-nucleo shuttling of eEF1Bβ might provide as well a re-distribution of its partners between these cellular compartments. Leucine-zipper motif present in the eEF1Bβ molecule [72] can be responsible for these multiple and reversible interactions.…”