Open AccessThe Human Fragile X Mental Retardation Protein Inhibits the Elongation Step of Translation through Its RGG and C-Terminal Domains
Author(s) -
Youssi Momen Athar,
Simpson Joseph
Publication year - 2020
Publication title -
biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.43
H-Index - 253
eISSN - 1520-4995
pISSN - 0006-2960
DOI - 10.1021/acs.biochem.0c00534
Subject(s) - translation (biology) , protein biosynthesis , eukaryotic translation , ribosome , messenger rna , internal ribosome entry site , microbiology and biotechnology , ctd , translational regulation , rna , eif4e , biology , chemistry , biochemistry , gene , oceanography , geology
The fragile X mental retardation protein (FMRP) is an RNA-binding protein that regulates the translation of numerous mRNAs in neurons. The precise mechanism of translational regulation by FMRP is unknown. Some studies have indicated that FMRP inhibits the initiation step of translation, whereas other studies have indicated that the elongation step of translation is inhibited by FMRP. To determine whether FMRP inhibits the initiation or the elongation step of protein synthesis, we investigated m 7 G-cap-dependent and IRES-driven, cap-independent translation of several reporter mRNAs in vitro . Our results show that FMRP inhibits both m 7 G-cap-dependent and cap-independent translation to similar degrees, indicating that the elongation step of translation is inhibited by FMRP. Additionally, we dissected the RNA-binding domains of hFMRP to determine the essential domains for inhibiting translation. We show that the RGG domain, together with the C-terminal domain (CTD), is sufficient to inhibit translation, while the KH domains do not inhibit mRNA translation. However, the region between the RGG domain and the KH2 domain may contribute as NT-hFMRP shows more potent inhibition than the RGG-CTD tail alone. Interestingly, we see a correlation between ribosome binding and translation inhibition, suggesting the RGG-CTD tail of hFMRP may anchor FMRP to the ribosome during translation inhibition.