Autor: |
Daley, Daniel O, Adams, Keith L, Clifton, Rachel, Qualmann, Svenja, Millar, A. Harvey, Palmer, Jeffrey D, Pratje, Elke, Whelan, James |
Předmět: |
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Zdroj: |
Plant Journal; Apr2002, Vol. 30 Issue 1, p11-21, 11p, 10 Diagrams, 1 Chart |
Abstrakt: |
Summary The evolutionarily recent transfer of the gene for cytochrome c oxidase subunit 2 (cox2 ) from the mitochondrion to the nucleus in legumes is shown to have involved novel gene-activation steps. The acquired mitochondrial targeting presequence is bordered by two introns. Characterization of the import of soybean Cox2 indicates that the presequence is cleaved in a three-step process which is independent of assembly. The final processing step takes place only in the mitochondria of legume species, and not in several non-legume plants. The unusually long presequence of 136 amino acids consists of three regions: the first 20 amino acids are required for mitochondrial targeting and can be replaced by another presequence; the central portion of the presequence is required for efficient import of the Cox2 protein into mitochondria; and the last 12 amino acids, derived from the mitochondrially encoded protein, are required for correct maturation of the imported protein. The acquisition of a unique presequence, and the capacity for legume mitochondria to remove this presequence post-import, are considered to be essential adaptations for targeting of Cox2 to the mitochondrion and therefore activation of the transferred gene in the nucleus. [ABSTRACT FROM AUTHOR] |
Databáze: |
Complementary Index |
Externí odkaz: |
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