Succinate dehydrogenase b mRNA of Drosophila melanogaster has a functional iron-responsive element in its 5'-untranslated region.
Iron-responsive elements (IREs) are cis-acting mRNA stem-loop structures that specifically bind cytoplasmic iron regulatory proteins (IRPs). IRP-IRE interactions mediate the coordinate post-transcriptional regulation of key proteins in iron metabolism, such as ferritin, transferrin receptor, and erythroid 5-aminolevulinic acid synthase. Depending on whether the IRE is located in the 5'- or 3'-untranslated region (UTR), binding of IRP will inhibit mRNA translation or degradation, respectively. Here we describe a new IRE in the 5'-UTR of succinate dehydrogenase subunit b (SDHb) mRNA of Drosophila melanogaster. The SDHb IRE binds in vitro to vertebrate and insect IRPs with a high affinity equal to that of human ferritin H chain IRE. Under conditions of iron deprivation, SDHb mRNA of Drosophila SL-2 cells shifts to a non-polysome-bound pool. Moreover, translation of a human growth hormone mRNA with the SDHb IRE in its 5'-UTR is iron-dependent in stably transfected L cells. We conclude that the SDHb IRE mediates translational inhibition both in insect and vertebrate cells. This constitutes the first identification of a functional IRE in insects. Furthermore, Drosophila SDHb represents the second example, after porcine mitochondrial aconitase, of an enzyme of the citric acid cycle whose mRNA possesses all necessary features for translational regulation by cellular iron levels.
Swiss Institute for Experimental Cancer Research, Epalinges s/Lausanne, Switzerland.
S A
SA
Kohler
B R
BR
Henderson
L C
LC
Kühn
D000818:Animals; D001483:Base Sequence; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular; D017931:DNA Primers; D004331:Drosophila melanogaster / Q000201:enzymology* / Q000235:genetics; D005293:Ferritins / Q000235:genetics; D013006:Growth Hormone / Q000096:biosynthesis*; D006801:Humans; D007313:Insecta; D007501:Iron / Q000494:pharmacology*; D035925:Iron-Regulatory Proteins; D007739:L Cells; D046911:Macromolecular Substances; D008565:Membrane Proteins; D051379:Mice; D006899:Mixed Function Oxygenases; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis; D013385:Succinate Dehydrogenase / Q000235:genetics*; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014714:Vertebrates
D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D017931:DNA Primers; D035925:Iron-Regulatory Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D013006:Growth Hormone; D005293:Ferritins; D007501:Iron; C498841:Asph protein, mouse; D006899:Mixed Function Oxygenases; C419389:ASPH protein, human; D013385:Succinate Dehydrogenase