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The Arabidopsis Bio2 protein requires mitochondrial targeting for activity

The Arabidopsis Bio2 protein requires mitochondrial targeting for activity Mitochondria are involved in the production of various vitamins, such as biotin, in plants. It is unclear why these biosynthetic pathways have been maintained partly or entirely within the mitochondria throughout evolution. The last step in biotin biosynthesis occurs within the mitochondria and is catalyzed by the biotin synthase complex containing the BIO2 gene product. We investigated whether the Arabidopsis Bio2 enzyme could function outside mitochondria, by trying to complement a bio2 mutant with a truncated version of BIO2 lacking the region encoding the mitochondrial targeting sequence. We describe the characterization of a new T-DNA allele of bio2, with the sole phenotype of an absence of biotin production, in contrast to the previously characterized EMS bio2 allele (Patton et al. 1998, Plant Physiol 116(3):935–946). We found that a cytosolic version of the Bio2 protein could not complement this mutant. Supplementation with the substrate dethiobiotin (DTB) also failed to rescue the mutant phenotype. Thus, the lack of availability of DTB in the cytosol is not the only factor preventing this reaction from occurring outside mitochondria. Bio2 requires mitochondrial targeting for activity, enabling it to fulfill its role in biotin synthesis. The reaction catalyzed by Bio2 may be subject to biochemical constraints, and the apparent close connection with the mitochondrial Fe-S machinery may account for the reaction being retained within the organelle. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant Molecular Biology Springer Journals

The Arabidopsis Bio2 protein requires mitochondrial targeting for activity

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References (39)

Publisher
Springer Journals
Copyright
Copyright © 2006 by Springer Science+Business Media B.V.
Subject
Life Sciences; Plant Pathology; Plant Sciences ; Plant Sciences
ISSN
0167-4412
eISSN
1573-5028
DOI
10.1007/s11103-006-9034-x
pmid
16897469
Publisher site
See Article on Publisher Site

Abstract

Mitochondria are involved in the production of various vitamins, such as biotin, in plants. It is unclear why these biosynthetic pathways have been maintained partly or entirely within the mitochondria throughout evolution. The last step in biotin biosynthesis occurs within the mitochondria and is catalyzed by the biotin synthase complex containing the BIO2 gene product. We investigated whether the Arabidopsis Bio2 enzyme could function outside mitochondria, by trying to complement a bio2 mutant with a truncated version of BIO2 lacking the region encoding the mitochondrial targeting sequence. We describe the characterization of a new T-DNA allele of bio2, with the sole phenotype of an absence of biotin production, in contrast to the previously characterized EMS bio2 allele (Patton et al. 1998, Plant Physiol 116(3):935–946). We found that a cytosolic version of the Bio2 protein could not complement this mutant. Supplementation with the substrate dethiobiotin (DTB) also failed to rescue the mutant phenotype. Thus, the lack of availability of DTB in the cytosol is not the only factor preventing this reaction from occurring outside mitochondria. Bio2 requires mitochondrial targeting for activity, enabling it to fulfill its role in biotin synthesis. The reaction catalyzed by Bio2 may be subject to biochemical constraints, and the apparent close connection with the mitochondrial Fe-S machinery may account for the reaction being retained within the organelle.

Journal

Plant Molecular Biology – Springer Journals

Published: Aug 1, 2006

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