eIF2γ mutation that disrupts eIF2 complex integrity links intellectual disability to impaired translation initiation.
Together with GTP and initiator methionyl-tRNA, translation initiation factor eIF2 forms a ternary complex that binds the 40S ribosome and then scans an mRNA to select the AUG start codon for protein synthesis. Here, we show that a human X-chromosomal neurological disorder characterized by intellectual disability and microcephaly is caused by a missense mutation in eIF2γ (encoded by EIF2S3), the core subunit of the heterotrimeric eIF2 complex. Biochemical studies of human cells overexpressing the eIF2γ mutant and of yeast eIF2γ with the analogous mutation revealed a defect in binding the eIF2β subunit to eIF2γ. Consistent with this loss of eIF2 integrity, the yeast eIF2γ mutation impaired translation start codon selection and eIF2 function in vivo in a manner that was suppressed by overexpressing eIF2β. These findings directly link intellectual disability to impaired translation initiation, and provide a mechanistic basis for the human disease due to partial loss of eIF2 function.
Institute of Human Genetics, University of Ulm, Ulm, Germany. guntram.borck@uni-ulm.de
Guntram
G
Borck
Byung-Sik
BS
Shin
Barbara
B
Stiller
Aviva
A
Mimouni-Bloch
Holger
H
Thiele
Joo-Ran
JR
Kim
Meghna
M
Thakur
Cindy
C
Skinner
Lara
L
Aschenbach
Pola
P
Smirin-Yosef
Adi
A
Har-Zahav
Gudrun
G
Nürnberg
Janine
J
Altmüller
Peter
P
Frommolt
Kay
K
Hofmann
Osnat
O
Konen
Peter
P
Nürnberg
Arnold
A
Munnich
Charles E
CE
Schwartz
Doron
D
Gothelf
Laurence
L
Colleaux
Thomas E
TE
Dever
Christian
C
Kubisch
Lina
L
Basel-Vanagaite
D000595:Amino Acid Sequence; D001483:Base Sequence; D015852:Eukaryotic Initiation Factor-2 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D008958:Models, Molecular; D020125:Mutation, Missense; D010442:Peptide Chain Initiation, Translational / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
D015852:Eukaryotic Initiation Factor-2; D029701:Saccharomyces cerevisiae Proteins