Investigations of plant mitochondrial protein import have been very limited and few reports exist in the literature. The work presented in this thesis describes the development of an <i>in vitro Zea mays</i> mitochondrial protein import system, which has enabled the import of plant nuclear-encoded mitochondrial proteins to be examined. This <i>Z.mays</i> import system was characterised and partially optimised with the <i>Nicotiana plumbaginifolia</i> manganese superoxide dismutase (MnSOD). Results suggest that the energy requirements for protein import into plant mitochondria are similar to those of <i>Saccharomyces cerevisiae</i> and <i>Neurospora crassa</i>, requiring both an energised inner mitochondrial membrane and ATP. The inclusion of 1,10-phenanthroline inhibited the processing, but not the import of MnSOD and indicated that the processing activity within <i>Z.mays</i> mitochondria was dependent upon the presence of metal ions. The plant mitochondrial processing protease may therefore be similar to the characterised <i>S.cerevisiae</i> and <i>N.crassa</i> matrix processing protease. The import of the <i>Z.mays</i> adenine nucleotide translocator (ANT) protein was then investigated. Unlike the ANT of <i>S.cerevisiae</i> and <i>N. crassa</i>, this plant ANT was synthesised as a precursor protein, which was processed upon import into mitochondria isolated from both <i>Z.mays</i> and <i>Solanum tuberosum</i>. The subsequent isolation of an <i>S.tuberosum</i> ANT cDNA clone <i>PANT-1</i>, enabled the import of a second plant ANT to be investigated. Results corroborated the findings previously obtained with the <i>Z.mays</i> ANT and it was therefore concluded that the import of plant ANT proteins are distinctly different from those of <i>S.cerevisiae</i> and <i>N.crassa</i>.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:661587 |
| Date | January 1991 |
| Creators | Sarah, Caroline J. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/12898 |
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