Journal Article

Mitochondrial Localization of AtOXA1, an <i>Arabidopsis</i> Homologue of Yeast Oxa1p Involved in the Insertion and Assembly of Protein Complexes in Mitochondrial Inner Membrane

Wataru Sakamoto, Nathalie Spielewoy, Géraldine Bonnard, Minoru Murata and Henri Wintz

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 41, issue 10, pages 1157-1163
Published in print October 2000 | ISSN: 0032-0781
Published online October 2000 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcd045
Mitochondrial Localization of AtOXA1, an Arabidopsis Homologue of Yeast Oxa1p Involved in the Insertion and Assembly of Protein Complexes in Mitochondrial Inner Membrane

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  • Biochemistry
  • Molecular and Cell Biology
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Components of some protein complexes present in the inner membrane of mitochondria are encoded in both nuclear and mitochondrial genomes, and correct sorting and assembly of these proteins is necessary for proper respiratory function. Recent studies in yeast suggest that Oxa1p, a protein conserved between prokaryotes and eukaryotes, is an essential factor for protein sorting and assembly into membranes. We previously identified AtOXA1, an Arabidopsis homologue of OXA1 by functional complementation of a yeast oxa1 mutant. In this study, we investigated the genomic organization of AtOXA1 and localization of the AtOXA1 protein. Characterization of the AtOXA1 genomic region indicated that the gene consists of 10 exons and is located on chromosome V. A database search also revealed another gene coding for a putative protein homologous to AtOXA1 on chromosome II. Transient expression of a green fluorescent protein (GFP) fusion in suspension-cultured tobacco cells showed that AtOXA1 is targeted into mitochondria by its N-terminal presequence. Antibodies raised against AtOXA1 recognized a 38-kDa intrinsic protein of the inner mitochondrial membrane. Thus, localization of AtOXA1 in the mitochondrial inner membrane, together with our previous complementation experiment in yeast, suggested that it is a functional homologue of Oxa1p.

Keywords: Key words: Arabidopsis thaliana — Green fluorescent protein (GFP) — Inner membrane — Mitochondria — OXA1.; Abbreviations: CaMV, cauliflower mosaic virus; Cytc1, cytochrome c1; EGTA, ethylene glycol-bis(β-aminoethyl ether)N,N,N ′N′-tetraacetic acid; GFP, green fluorescent protein; IPTG, isopropylβ d-thiogalactopyranoside; Mn-SOD, manganese superoxide dismutase; MOPS, 3-(N-morpholino)propanesulphonic acid; Nad9, subunit 9 of NADH dehydrogenase, PMSF, phenylmethylsulfonyl fluoride.; The nucleotide sequence reported in this paper has been submitted to the DDBJ, EMBL, GenBank under accession number AB035892.

Journal Article.  5143 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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