Deinococcus radiodurans' SRA-HNH domain containing protein Shp (Dr1533) is involved in faithful genome inheritance maintenance following DNA damage |
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Authors: | Alex Ferrandi Federica Castani Mauro Pitaro Sara Tagliaferri Claire Bouthier de la Tour Rosa Alduina Suzanne Sommer Mauro Fasano Paola Barbieri Monica Mancini Ian Marc Bonapace |
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Institution: | 1. Department of Biotechnology and Life Sciences, University of Insubria, Via Manara 7, Busto Arsizio, VA, Italy;2. Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze, Palermo, Italy;3. Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, France and Institut de Génétique et Microbiologie - Université Paris-Sud, Paris, France;4. Department of Sciences and High technology, University of Insubria, Via Manara 7, Busto Arsizio, VA, Italy |
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Abstract: | BackgroundDeinococcus radiodurans R1 (DR) survives conditions of extreme desiccation, irradiation and exposure to genotoxic chemicals, due to efficient DNA breaks repair, also through Mn2+ protection of DNA repair enzymes.MethodsPossible annotated domains of the DR1533 locus protein (Shp) were searched by bioinformatic analysis. The gene was cloned and expressed as fusion protein. Band-shift assays of Shp or the SRA and HNH domains were performed on oligonucleotides, genomic DNA from E. coli and DR. shp knock-out mutant was generated by homologous recombination with a kanamycin resistance cassette.ResultsDR1533 contains an N-terminal SRA domain and a C-terminal HNH motif (SRA-HNH Protein, Shp). Through its SRA domain, Shp binds double-strand oligonucleotides containing 5mC and 5hmC, but also unmethylated and mismatched cytosines in presence of Mn2+. Shp also binds to Escherichia coli dcm+ genomic DNA, and to cytosine unmethylated DR and E. coli dcm? genomic DNAs, but only in presence of Mn2+. Under these binding conditions, Shp displays DNAse activity through its HNH domain. Shp KO enhanced >100 fold the number of spontaneous mutants, whilst the treatment with DNA double strand break inducing agents enhanced up to 3-log the number of survivors.ConclusionsThe SRA-HNH containing protein Shp binds to and cuts 5mC DNA, and unmethylated DNA in a Mn2+ dependent manner, and might be involved in faithful genome inheritance maintenance following DNA damage.General significanceOur results provide evidence for a potential role of DR Shp protein for genome integrity maintenance, following DNA double strand breaks induced by genotoxic agents. |
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Keywords: | DR1533 locus SRA domain DNA cytosine-methylation 2+ DNA damage Genotoxic agents |
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