The 28.5-kDa iron-sulfur protein of mitochondrial complex I is encoded in the nucleus in plants |
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Authors: | K Schmidt-Bleek V Heiser O Thieck A Brennicke and L Grohmann |
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Institution: | (1) Institut für Genbiologische Forschung, Ihnestra?e 63, D-14195 Berlin, Germany, DE;(2) Allgemeine Botanik, Universit?t Ulm, Albert-Einstein-Allee, D-89069 Ulm, Germany, DE |
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Abstract: | The intrinsic 28.5-kDa iron-sulfur protein of complex I in the mitochondrial respiratory chain is encoded in the nucleus
in animals and fungi, but specified by a mitochondrial gene in trypanosomes. In plants, the homologous protein is now found
to be encoded by a single-copy nuclear gene in Arabidopsis thaliana and by two nuclear genes in potato. The cysteine motifs involved in binding two iron-sulfur clusters are conserved in the
plant protein sequences. The locations of the seven introns, with sizes between 60 and 1700 nucleotides, are identical in
the A. thaliana and the two potato genes, while their primary sequences diverge considerably. The A+T contents of the intron sequences range
between 61% and 73%, as is characteristic for dicot plants, but are in some instances not higher than in the adjacent exons.
Here, differences in T content may instead serve to discriminate exons and introns. In potato, both genes are expressed, with
the highest levels found in flowers. Sequence similarities between the homologous nuclear and mitochondrial genes indicate
that the nuclear forms in animals and plants originate from the endosymbiont genome.
Received: 28 May 1996 / Accepted: 22 August 1996 |
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Keywords: | Plant mitochondria Iron-sulfur protein Complex I Nuclear gene Introns |
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