title: Degradation of Escherichia coli RecN aggregates by ClpXP protease and its implications for DNA damage tolerance.
abstract: Protein degradation in bacteria plays a dynamic and critical role in the cellular response to environmental stimuli such as heat shock and DNA damage and in removing damaged proteins or protein aggregates. Escherichia coli recN is a member of the structural maintenance of chromosomes family and is required for DNA double strand break (DSB) repair. This study shows that RecN protein has a short half-life and its degradation is dependent on the cytoplasmic protease ClpXP and a degradation signal at the C terminus of RecN. In cells with DNA DSBs, green fluorescent protein-RecN localized in discrete foci on nucleoids and formed visible aggregates in the cytoplasm, both of which disappeared rapidly in wild-type cells when DSBs were repaired. In contrast, in DeltaclpX cells, RecN aggregates persisted in the cytoplasm after release from DNA damage. Furthermore, analysis of cells experiencing chronic DNA damage revealed that proteolytic removal of RecN aggregates by ClpXP was important for cell viability. These data demonstrate that ClpXP is a critical factor in the cellular clearance of cytoplasmic RecN aggregates from the cell and therefore plays an important role in DNA damage tolerance.
authors.affiliation: Laboratory of Genome Dynamics, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan.
authors.forename: Kohji
authors.initials: K
authors.lastname: Nagashima
authors.forename: Yoshino
authors.initials: Y
authors.lastname: Kubota
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Shibata
authors.forename: Chikako
authors.initials: C
authors.lastname: Sakaguchi
authors.forename: Hideo
authors.initials: H
authors.lastname: Shinagawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Hishida
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D003593:Cytoplasm / Q000201:enzymology / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004262:DNA Restriction Enzymes / Q000737:chemistry* / Q000378:metabolism; D049071:Endopeptidase Clp / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D016685:Mitomycin / Q000494:pharmacology; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D049452:Green Fluorescent Proteins; D016685:Mitomycin; D004262:DNA Restriction Enzymes; C047879:RecN protein, Bacteria; C483573:ClpXP protease, E coli; D049071:Endopeptidase Clp