Characterization of a novel ß-barrel protein (AtOM47) from the mitochondrial outer membrane of Arabidopsis thaliana

L. Li, Szymon Kubiszewski-Jakubiak, J. Radomiljac, Y. Wang, S.R. Law, O. Keech, R. Narsai, O. Berkowitz, Owen Duncan, Monika W. Murcha, J. Whelan

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7 Citations (Scopus)

Abstract

© 2016 The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

In plant cells, mitochondria are major providers of energy and building blocks for growth and development as well as abiotic and biotic stress responses. They are encircled by two lipid membranes containing proteins that control mitochondrial function through the import of macromolecules and metabolites. Characterization of a novel ß-barrel protein, OUTER MEMBRANE PROTEIN 47 (OM47), unique to the green lineage and related to the voltage-dependent anion channel (VDAC) protein family, showed that OM47 can complement a VDAC mutant in yeast. Mutation of OM47 in Arabidopsis thaliana by T-DNA insertion had no effect on the import of proteins, such as the ß-barrel proteins translocase of the outer membrane 40 (TOM40) or sorting and assembly machinery 50 (SAM50), into mitochondria. Molecular and physiological analyses revealed a delay in chlorophyll breakdown, higher levels of starch, and a delay in the induction of senescence marker genes in the mutant lines. While there was a reduction of >90% in OM47 protein in mitochondria isolated from 3-week-old om47 mutants, in mitochondria isolated from 8-week-old plants OM47 levels were similar to that of the wild type. This recovery was achieved by an up-regulation of OM47 transcript abundance in the mutants. Combined, these results highlight a role in leaf senescence for this plant-specific ß-barrel protein, probably mediating the recovery and recycling of chloroplast breakdown products by transporting metabolic intermediates into and out of mitochondria.

Original languageEnglish
Pages (from-to)6061-6075
Number of pages15
JournalJournal of Experimental Botany
Volume67
Issue number21
Early online date6 Oct 2016
DOIs
Publication statusPublished - 1 Nov 2016

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