title: An oncoprotein from the plant pathogen agrobacterium has histone chaperone-like activity.
abstract: Protein 6b, encoded by T-DNA from the pathogen Agrobacterium tumefaciens, stimulates the plant hormone-independent division of cells in culture in vitro and induces aberrant cell growth and the ectopic expression of various genes, including genes related to cell division and meristem-related class 1 KNOX homeobox genes, in 6b-expressing transgenic Arabidopsis thaliana and Nicotiana tabacum plants. Protein 6b is found in nuclei and binds to several plant nuclear proteins. Here, we report that 6b binds specifically to histone H3 in vitro but not to other core histones. Analysis by bimolecular fluorescence complementation revealed an interaction in vivo between 6b and histone H3. We recovered 6b from a chromatin fraction from 6b-expressing plant cells. A supercoiling assay and digestion with micrococcal nuclease indicated that 6b acts as a histone chaperone with the ability to mediate formation of nucleosomes in vitro. Mutant 6b, lacking the C-terminal region that is required for cell division-stimulating activity and interaction with histone H3, was deficient in histone chaperone activity. Our results suggest a relationship between alterations in nucleosome structure and the expression of growth-regulating genes on the one hand and the induction of aberrant cell proliferation on the other.
authors: Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan.
authors: Shinji
authors: S
authors: Terakura
authors: Yoshihisa
authors: Y
authors: Ueno
authors: Hideaki
authors: H
authors: Tagami
authors: Saeko
authors: S
authors: Kitakura
authors: Chiyoko
authors: C
authors: Machida
authors: Hiroetsu
authors: H
authors: Wabiko
authors: Hiroji
authors: H
authors: Aiba
authors: Léon
authors: L
authors: Otten
authors: Hironaka
authors: H
authors: Tsukagoshi
authors: Kenzo
authors: K
authors: Nakamura
authors: Yasunori
authors: Y
authors: Machida
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D002843:Chromatin / Q000378:metabolism*; D017343:Genes, Plant; D006657:Histones / Q000378:metabolism*; D008934:Mitogens; D018832:Molecular Chaperones / Q000378:metabolism*; D008969:Molecular Sequence Data; D015513:Oncogene Proteins / Q000378:metabolism*; D019441:Plant Epidermis / Q000166:cytology; D018515:Plant Leaves / Q000166:cytology; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012231:Rhizobium / Q000378:metabolism*; D014026:Nicotiana / Q000166:cytology
chemical_list: D002843:Chromatin; D006657:Histones; D008934:Mitogens; D018832:Molecular Chaperones; D015513:Oncogene Proteins; D012333:RNA, Messenger