NOA1 is an essential GTPase required for mitochondrial protein synthesis.
Nitric oxide associated-1 (NOA1) is an evolutionarily conserved guanosine triphosphate (GTP) binding protein that localizes predominantly to mitochondria in mammalian cells. On the basis of bioinformatic analysis, we predicted its possible involvement in ribosomal biogenesis, although this had not been supported by any experimental evidence. Here we determine NOA1 function through generation of knockout mice and in vitro assays. NOA1-deficient mice exhibit midgestation lethality associated with a severe developmental defect of the embryo and trophoblast. Primary embryonic fibroblasts isolated from NOA1 knockout embryos show deficient mitochondrial protein synthesis and a global defect of oxidative phosphorylation (OXPHOS). Additionally, Noa1⁻/⁻ cells are impaired in staurosporine-induced apoptosis. The analysis of mitochondrial ribosomal subunits from Noa1⁻/⁻ cells by sucrose gradient centrifugation and Western blotting showed anomalous sedimentation, consistent with a defect in mitochondrial ribosome assembly. Furthermore, in vitro experiments revealed that intrinsic NOA1 GTPase activity was stimulated by bacterial ribosomal constituents. Taken together, our data show that NOA1 is required for mitochondrial protein synthesis, likely due to its yet unidentified role in mitoribosomal biogenesis. Thus, NOA1 is required for such basal mitochondrial functions as adenosine triphosphate (ATP) synthesis and apoptosis.
Development & Disease Group, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany. kolanshy@molgen.mpg.de
Mateusz
M
Kolanczyk
Markus
M
Pech
Tomasz
T
Zemojtel
Hiroshi
H
Yamamoto
Ivan
I
Mikula
Maria-Antonietta
MA
Calvaruso
Mariël
M
van den Brand
Ricarda
R
Richter
Bjoern
B
Fischer
Anita
A
Ritz
Nadine
N
Kossler
Boris
B
Thurisch
Ralf
R
Spoerle
Jan
J
Smeitink
Uwe
U
Kornak
Danny
D
Chan
Martin
M
Vingron
Pavel
P
Martasek
Robert N
RN
Lightowlers
Leo
L
Nijtmans
Markus
M
Schuelke
Knud H
KH
Nierhaus
Stefan
S
Mundlos
D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000002:abnormalities; D047108:Embryonic Development; D005313:Fetal Death; D005347:Fibroblasts; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D017403:In Situ Hybridization; D051379:Mice; D018345:Mice, Knockout; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000096:biosynthesis*; D010085:Oxidative Phosphorylation; D014176:Protein Biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering; D012270:Ribosomes / Q000378:metabolism; D019311:Staurosporine / Q000378:metabolism
D024101:Mitochondrial Proteins; D034741:RNA, Small Interfering; D000255:Adenosine Triphosphate; D020558:GTP Phosphohydrolases; C559566:NOA1 protein, mouse; D019311:Staurosporine