title: Post-translational mechanisms are associated with fertility restoration of cytoplasmic male sterility in sugar beet (Beta vulgaris).
abstract: Genetic conflict between cytoplasmically inherited elements and nuclear genes arising from their different transmission patterns can be seen in cytoplasmic male sterility (CMS), the mitochondrion-encoded inability to shed functional pollen. CMS is associated with a mitochondrial open reading frame (ORF) that is absent from non-sterility inducing mitochondria (S-orf). Nuclear genes that suppress CMS are called restorer-of-fertility (Rf) genes. Post-transcriptional and translational repression of S-orf mediates the molecular action of Rf that encodes a class of RNA-binding proteins with pentatricopeptide repeat (PPR) motifs. Besides the PPR-type of Rfs, there are also non-PPR Rfs, but the molecular interactions between non-PPR Rf and S-orf have not been described. In this study, we investigated the interaction of bvORF20, a non-PPR Rf from sugar beet (Beta vulgaris), with preSatp6, the S-orf from sugar beet. Anthers expressing bvORF20 contained a protein that interacted with preSATP6 protein. Analysis of anthers and transgenic calli expressing a FLAG-tagged bvORF20 suggested the binding of preSATP6 to bvORF20. To see the effect of bvORF20 on preSATP6, which exists as a 250-kDa protein complex in CMS plants, signal bands of preSATP6 in bvORF20-expressing and non-expressing anthers were compared by immunoblotting combined with Blue Native polyacrylamide gel electrophoresis. The signal intensity of the 250-kDa band decreased significantly, and 200- and 150-kDa bands appeared in bvORF20-expressing anthers. Transgenic callus expressing bvORF20 also generated the 200- and 150-kDa bands. The 200-kDa complex is likely to include both preSATP6 and bvORF20. Post-translational interaction between preSATP6 and bvORF20 appears to alter the higher order structure of preSATP6 that may lead to fertility restoration in sugar beet.
authors.affiliation: Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Kita-ku, Sapporo, Hokkaido, 060-8589, Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Kitazaki
authors.affiliation: Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Kita-ku, Sapporo, Hokkaido, 060-8589, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Arakawa
authors.affiliation: Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Kita-ku, Sapporo, Hokkaido, 060-8589, Japan.
authors.forename: Muneyuki
authors.initials: M
authors.lastname: Matsunaga
authors.affiliation: Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Kita-ku, Sapporo, Hokkaido, 060-8589, Japan.
authors.forename: Rika
authors.initials: R
authors.lastname: Yui-Kurino
authors.affiliation: Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Kita-ku, Sapporo, Hokkaido, 060-8589, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Matsuhira
authors.affiliation: Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Kita-ku, Sapporo, Hokkaido, 060-8589, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Mikami
authors.affiliation: Research Faculty of Agriculture, Hokkaido University, N-9, W-9, Kita-ku, Sapporo, Hokkaido, 060-8589, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Kubo
mesh_terms: D027461:Beta vulgaris / Q000378:metabolism / Q000502:physiology*; D003593:Cytoplasm / Q000378:metabolism*; D005298:Fertility; D008565:Membrane Proteins / Q000378:metabolism*; D016366:Open Reading Frames; D010940:Plant Proteins / Q000378:metabolism*; D011485:Protein Binding; D011499:Protein Processing, Post-Translational
chemical_list: D008565:Membrane Proteins; D010940:Plant Proteins
keywords: Beta vulgaris ssp. vulgaris; Blue Native polyacrylamide gel electrophoresis; cytoplasmic male sterility; fertility restoration; plant mitochondria; protein-protein interaction