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Biosynthesis of mitochondrial citrate synthase in neurospora crassa
Author(s) -
Harmey Matthew A.,
Neupert Walter
Publication year - 1979
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 - 10.1016/0014-5793(79)80569-4
Subject(s) - library science , neurospora crassa , biology , computer science , genetics , gene , mutant
The transfer of mitochondrial proteins coded for by nuclear DNA from their site of synthesis into the mitochondria is currently attracting much attention. Early proposals that this transfer occurs by a co-translational mechanism [ 1 ] have not been substantiated, rather evidence has been produced which supports a post-translational mechanism involving extramitochondrial precursors [2-61. The nature of these extramitochondrial precursors has been investigated for a number of proteins [4-l 21. In the case of some proteins the initial translation products are larger than the mature protein [6-8,l l] while this does not hold for others [4,5,9,10,12]. As no general rule of behaviour has been observed and no general hypothesis advanced it is necessary to investigate the formation of proteins having different mitochondrial locations. In this context we have studied the synthesis of citrate synthase (EC 4.1.3.7), a soluble matrix protein consisting of two identical subunits [13,14]. The data presented indicate that this protein is synthesized as a larger molecular weight precursor. Synthesis of the precursor and its subsequent transfer into the mitochondria are temporally separate in whole cells. Conversion of the precursor to the mature protein is by post-translational cleavage.