Abstract
The interaction between the ribosome and the endoplasmic reticulum-located Sec61 protein translocon is mediated through an arginine residue of Sec61α, which is conserved in all prokaryotic and eukaryotic orthologues characterized to date. Using in silico approaches we report that instead of arginine, this ribosome-interaction function is most likely discharged by a lysine residue in the protist Giardia lamblia. This functional substitution of the R with a K in GlSec61α may have taken place to accommodate a G-rich rRNA.Electronic supplementary materialThe online version of this article (doi:10.1186/s13062-015-0087-0) contains supplementary material, which is available to authorized users.
Highlights
The interaction between the ribosome and the endoplasmic reticulum-located Sec61 protein translocon is mediated through an arginine residue of Sec61α, which is conserved in all prokaryotic and eukaryotic orthologues characterized to date
The protein conducting channel is formed by the essential subunit Sec61α, which is composed of ten transmembrane helices
Structural studies show that the cytoplasmic loop located between transmembrane helices 8 and 9 of Sec61α contains a conserved R residue that is present in all orthologues of Sec61α described far [3,4,5]
Summary
The interaction between the ribosome and the endoplasmic reticulum-located Sec61 protein translocon is mediated through an arginine residue of Sec61α, which is conserved in all prokaryotic and eukaryotic orthologues characterized to date. This substantial change in conformation of loop 8/9 caused a significant alteration in the position of the K residue and the simulations, based on both models, indicate that K426 switches towards the incoming RNA (Fig. 1b and Additional file 3).
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