title: Cloning, expression, and characterization of a methionine sulfoxide reductase B gene from Nicotiana tabacum.
abstract: Reactive oxygen species (ROS) are generated during normal aerobic metabolism and in plants exposed to environmental stress. Methionine (Met) residues are particularly sensitive to ROS-mediated oxidation, leading to the formation of methionine sulfoxide (MetSO) under mild oxidative conditions. Methionine sulfoxide reductase (MSR) repairs oxidized Met and protects plants from oxidative damage. Herein, we identified a tobacco (Nicotiana tabacum) MSRB gene, referred to as NtMSRB3. Analysis of the sequence showed that the NtMSRB3 protein had four typical motifs in a SelR domain, which is known as the catalytic region of MSRBs. NtMSRB3 specifically reduced the R epimer of MetSO and converted either free MetSO or Dabsyl-MetSO in the presence of dithiothreitol. Escherichia coli cells harboring NtMSRB3 displayed relative high viability under H₂O₂ stress. Subcellular localization of NtMSRB3 revealed that it was a plastid-targeted protein. Furthermore, the semi-quantitative reverse transcription polymerase chain reaction assay showed that NtMSRB3 was upregulated apparently by abscisic acid, salt, cold, and methyl viologen stress within 24 h of treatment.
authors.affiliation: Department of Medical Biotechnology, College of Biomedical Science, Kangwon National University, Chuncheon, 200-701, Gangwon-do, South Korea.
authors.forename: Likun
authors.initials: L
authors.lastname: Liu
authors.forename: Myeong-Hyeon
authors.initials: MH
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D004926:Escherichia coli; D007700:Kinetics; D051150:Methionine Sulfoxide Reductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018087:Plastids / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013312:Stress, Physiological; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics / Q000502:physiology
chemical_list: D010940:Plant Proteins; D011994:Recombinant Proteins; D051150:Methionine Sulfoxide Reductases