In vitro synthesis and processing of components of the Ascaris suum pyruvate dehydrogenase complex.
Poly(A)+ RNA was isolated from Ascaris suum body wall muscle and translated in a cell-free rabbit reticulocyte lysate system. Specific antisera and immunoglobulins against the alpha-pyruvate dehydrogenase and dihydrolipoyl transacetylase components of ascarid pyruvate dehydrogenase complex were used to immunoprecipitate individual radiolabelled polypeptides from the in vitro translation mixtures. Both polypeptides appeared to be synthesized as preproteins about 1.5 and 8 kDa larger than the corresponding native proteins. Incubation of the dihydrolipoyl transacetylase preprotein with an ascarid high-speed mitochondrial supernatant fraction resulted in the formation of a polypeptide with apparent molecular weight intermediate in size between the preprotein and the native enzyme. This processing was insensitive to phenylmethylsulfonyl fluoride and leupeptin but was completely abolished by EDTA. These results suggest that in A.suum, as in other organisms, mitochondrial matrix proteins coded by the nuclear genome are synthesized as larger preproteins and processed by a specific, metal-dependent mitochondrial matrix protease.
Ruff
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Department of Biology, University of Toledo, OH 43606.
Desai
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S
DuBrul
E F
EF
Komuniecki
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R
D000123:Acetyltransferases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001200:Ascaris / Q000201:enzymology* / Q000235:genetics; D051047:Dihydrolipoyllysine-Residue Acetyltransferase; D004591:Electrophoresis, Polyacrylamide Gel; D004792:Enzyme Precursors / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007118:Immunoassay; D011061:Poly A / Q000235:genetics; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D011768:Pyruvate Dehydrogenase Complex / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D012313:RNA / Q000235:genetics
D004792:Enzyme Precursors; D011498:Protein Precursors; D011768:Pyruvate Dehydrogenase Complex; D011061:Poly A; D012313:RNA; D000123:Acetyltransferases; D051047:Dihydrolipoyllysine-Residue Acetyltransferase