title: Functional characterization of the principal sigma factor RpoD of phytoplasmas via an in vitro transcription assay.
abstract: Phytoplasmas (class, Mollicutes) are insect-transmissible and plant-pathogenic bacteria that multiply intracellularly in both plants and insects through host switching. Our previous study revealed that phytoplasmal sigma factor rpoD of OY-M strain (rpoDOY) could be a key regulator of host switching, because the expression level of rpoDOY was higher in insect hosts than in plant hosts. In this study, we developed an in vitro transcription assay system to identify RpoDOY-dependent genes and the consensus promoter elements. The assay revealed that RpoDOY regulated some housekeeping, virulence, and host-phytoplasma interaction genes of OY-M strain. The upstream region of the transcription start sites of these genes contained conserved -35 and -10 promoter sequences, which were similar to the typical bacterial RpoD-dependent promoter elements, while the -35 promoter elements were variable. In addition, we searched putative RpoD-dependent genes based on these promoter elements on the whole genome sequence of phytoplasmas using in silico tools. The phytoplasmal RpoD seems to mediate the transcription of not only many housekeeping genes as the principal sigma factor, but also the virulence- and host-phytoplasma interaction-related genes exhibiting host-specific expression patterns. These results indicate that more complex mechanisms exist than previously thought regarding gene regulation enabling phytoplasmas to switch hosts.
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Miura
authors.affiliation: Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Komatsu
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Kensaku
authors.initials: K
authors.lastname: Maejima
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Takamichi
authors.initials: T
authors.lastname: Nijo
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Yugo
authors.initials: Y
authors.lastname: Kitazawa
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Tomomitsu
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Yusa
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Misako
authors.initials: M
authors.lastname: Himeno
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Kenro
authors.initials: K
authors.lastname: Oshima
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Shigetou
authors.initials: S
authors.lastname: Namba
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000378:metabolism; D016680:Genome, Bacterial; D007313:Insecta / Q000382:microbiology; D008969:Molecular Sequence Data; D045582:Phytoplasma / Q000235:genetics / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology; D010944:Plants / Q000382:microbiology; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor; D012321:DNA-Directed RNA Polymerases