title: Functional characterization and gene expression profiling of superoxide dismutase from plant pathogenic phytoplasma.
abstract: The rapid production of huge amounts of reactive oxygen species (ROS) is one of the responses of animal and plant cells induced under stress conditions, such as pathogenic bacterial infection. To protect against the cytotoxic ROS, it is important for pathogenic bacteria to inactivate ROS by employing their antioxidant enzymes like superoxide dismutase (SOD). Here, we cloned and characterized the sodA gene from the plant pathogenic bacterium, 'Candidatus Phytoplasma asteris' OY-W strain. This is the first description of gene expression and antioxidant enzymatic activity of SOD from a phytoplasma. We also demonstrated the sodA gene product (OY-SOD) functions as Mn-type SOD. Since other Mollicutes bacteria such as mycoplasmas do not possess sodA probably due to reductive evolution, it is intriguing that phytoplasmas possess sodA despite their lack of many metabolic genes, suggesting that OY-SOD may play an important role in the phytoplasma colonization of plants and insects. Moreover, Western blot analysis and real-time PCR revealed that OY-SOD is expressed when the phytoplasma is grown in both plant and insect hosts, suggesting it is functioning in both hosts. Possible role of SOD in protection against damage by host-derived ROS is discussed.
authors.affiliation: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Miura
authors.forename: Kyoko
authors.initials: K
authors.lastname: Sugawara
authors.forename: Yutaro
authors.initials: Y
authors.lastname: Neriya
authors.forename: Nami
authors.initials: N
authors.lastname: Minato
authors.forename: Takuya
authors.initials: T
authors.lastname: Keima
authors.forename: Misako
authors.initials: M
authors.lastname: Himeno
authors.forename: Kensaku
authors.initials: K
authors.lastname: Maejima
authors.forename: Ken
authors.initials: K
authors.lastname: Komatsu
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamaji
authors.forename: Kenro
authors.initials: K
authors.lastname: Oshima
authors.forename: Shigetou
authors.initials: S
authors.lastname: Namba
mesh_terms: D000818:Animals; D031202:Chrysanthemum; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D006430:Hemiptera / Q000382:microbiology; D045582:Phytoplasma / Q000201:enzymology* / Q000235:genetics*; D010935:Plant Diseases / Q000382:microbiology*; D017382:Reactive Oxygen Species; D017422:Sequence Analysis, DNA; D013482:Superoxide Dismutase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase