Kissing complex RNAs mediate interaction between the Fragile-X mental retardation protein KH2 domain and brain polyribosomes.
Fragile-X mental retardation is caused by loss of function of a single gene encoding the Fragile-X mental retardation protein, FMRP, an RNA-binding protein that harbors two KH-type and one RGG-type RNA-binding domains. Previous studies identified intramolecular G-quartet RNAs as high-affinity targets for the RGG box, but the relationship of RNA binding to FMRP function and mental retardation remains unclear. One severely affected patient harbors a missense mutation (I304N) within the second KH domain (KH2), and some evidence suggests this domain may be involved in the proposed role of FMRP in translational regulation. We now identify the RNA target for the KH2 domain as a sequence-specific element within a complex tertiary structure termed the FMRP kissing complex. We demonstrate that the association of FMRP with brain polyribosomes is abrogated by competition with the FMRP kissing complex RNA, but not by high-affinity G-quartet RNAs. We conclude that mental retardation associated with the I304N mutation, and likely the Fragile-X syndrome more generally, may relate to a crucial role for RNAs harboring the kissing complex motif as targets for FMRP translational regulation.
Darnell
Jennifer C
JC
Howard Hughes Medical Institute and Laboratory of Molecular Neuro-Oncology, The Rockefeller University, New York, New York, USA. darneje@rockefeller.edu
Fraser
Claire E
CE
Mostovetsky
Olga
O
Stefani
Giovanni
G
Jones
Thomas A
TA
Eddy
Sean R
SR
Darnell
Robert B
RB
D020816:Amino Acid Motifs / Q000235:genetics; D000818:Animals; D020029:Base Pairing; D001483:Base Sequence; D015153:Blotting, Western; D002540:Cerebral Cortex / Q000378:metabolism*; D004252:DNA Mutational Analysis; D017931:DNA Primers; D024202:Electrophoretic Mobility Shift Assay; D051860:Fragile X Messenger Ribonucleoprotein 1; D005600:Fragile X Syndrome / Q000235:genetics*; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D020125:Mutation, Missense / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D011132:Polyribosomes / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000502:physiology; D012313:RNA / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA
D017931:DNA Primers; D051860:Fragile X Messenger Ribonucleoprotein 1; D009419:Nerve Tissue Proteins; D012313:RNA; D016601:RNA-Binding Proteins; C497683:FMR1 protein, human; C497684:Fmr1 protein, mouse