title: Functional comparison of Deinococcus radiodurans Dps proteins suggests distinct in vivo roles.
abstract: Deinococcus radiodurans exhibits extreme resistance to DNA damage and is one of only few bacteria that encode two Dps (DNA protection during starvation) proteins. Dps-1 was shown previously to bind DNA with high affinity and to localize to the D. radiodurans nucleoid. A unique feature of Dps-2 is its predicted signal peptide. In the present paper, we report that Dps-2 assembly into a dodecamer requires the C-terminal extension and, whereas Dps-2 binds DNA with low affinity, it protects against degradation by reactive oxygen species. Consistent with a role for Dps-2 in oxidative stress responses, the Dps-2 promoter is up-regulated by oxidative stress, whereas the Dps-1 promoter is not. Although DAPI (4',6-diamidino-2-phenylindole) staining of Escherichia coli nucleoids shows that Dps-1 can compact genomic DNA, such nucleoid condensation is absent from cells expressing Dps-2. A fusion of EGFP (enhanced green fluorescent protein) to the Dps-2 signal peptide results in green fluorescence at the perimeter of D. radiodurans cells. The differential response of the Dps-1 and Dps-2 promoters to oxidative stress, the distinct cellular localization of the proteins and the differential ability of Dps-1 and Dps-2 to attenuate hydroxyl radical production suggest distinct functional roles; whereas Dps-1 may function in DNA metabolism, Dps-2 may protect against exogenously derived reactive oxygen species.
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Reon
authors.forename: Khoa H
authors.initials: KH
authors.lastname: Nguyen
authors.forename: Gargi
authors.initials: G
authors.lastname: Bhattacharyya
authors.forename: Anne
authors.initials: A
authors.lastname: Grove
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D034301:Deinococcus / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics; D006861:Hydrogen Peroxide / Q000737:chemistry; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic; D055503:Protein Multimerization; D055550:Protein Stability; D017382:Reactive Oxygen Species / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C083911:DPS protein, Bacteria; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D006861:Hydrogen Peroxide