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Increased synthesis and decreased stability of mitochondrial translation products in yeast as a result of loss of mitochondrial (NAD + )‐dependent isocitrate dehydrogenase
Author(s) -
de Jong Liesbeth,
Elzinga Sandra D.J,
McCammon Mark T,
Grivell Leslie A,
van der Spek Hans
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)02086-x
Subject(s) - isocitrate dehydrogenase , nad+ kinase , yeast , biochemistry , chemistry , mitochondrion , translation (biology) , idh1 , nadh dehydrogenase , dehydrogenase , enzyme , microbiology and biotechnology , mitochondrial dna , biology , mutation , gene , messenger rna
We have previously demonstrated that the yeast Krebs cycle enzyme NAD + ‐dependent isocitrate dehydrogenase (Idh) binds specifically and with high affinity to the 5′‐untranslated leader sequences of mitochondrial mRNAs in vitro and have proposed a role for the enzyme in the regulation of mitochondrial translation [Elzinga, S.D.J. et al. (2000) Curr. Genet., in press]. Although our studies initially failed to reveal any consistent correlation between idh disruption and mitochondrial translational activity, it is now apparent that compensatory extragenic suppressor mutations readily accumulate in idh disruption strains thereby masking mutant behaviour. Now, pulse‐chase protein labelling of isolated mitochondria from an Idh disruption mutant lacking suppressor mutations reveals a strong (2–3‐fold) increase in the synthesis of mitochondrial translation products. Strikingly, the newly synthesised proteins are more short‐lived than in mitochondria from wild‐type cells, their degradation occurring with a 2–3‐fold reduced half‐life. Enhanced degradation of translation products is also a feature of yeast mutants in which tethering/docking of mitochondrial mRNAs is disturbed. We therefore suggest that binding of Idh to mitochondrial mRNAs may suppress inappropriate translation of mitochondrial mRNAs.