title: ExoMeg1: a new exonuclease from metagenomic library.
abstract: DNA repair mechanisms are responsible for maintaining the integrity of DNA and are essential to life. However, our knowledge of DNA repair mechanisms is based on model organisms such as Escherichia coli, and little is known about free living and uncultured microorganisms. In this study, a functional screening was applied in a metagenomic library with the goal of discovering new genes involved in the maintenance of genomic integrity. One clone was identified and the sequence analysis showed an open reading frame homolog to a hypothetical protein annotated as a member of the Exo_Endo_Phos superfamily. This novel enzyme shows 3'-5' exonuclease activity on single and double strand DNA substrates and it is divalent metal-dependent, EDTA-sensitive and salt resistant. The clone carrying the hypothetical ORF was able to complement strains deficient in recombination or base excision repair, suggesting that the new enzyme may be acting on the repair of single strand breaks with 3' blockers, which are substrates for these repair pathways. Because this is the first report of an enzyme obtained from a metagenomic approach showing exonuclease activity, it was named ExoMeg1. The metagenomic approach has proved to be a useful tool for identifying new genes of uncultured microorganisms.
authors.affiliation: Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN, 59072-970, Brasil.
authors.forename: Rita C B
authors.initials: RC
authors.lastname: Silva-Portela
authors.affiliation: Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN, 59072-970, Brasil.
authors.forename: Fabíola M
authors.initials: FM
authors.lastname: Carvalho
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo (USP), São Paulo, Brasil.
authors.forename: Carolina P M
authors.initials: CP
authors.lastname: Pereira
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo (USP), São Paulo, Brasil.
authors.forename: Nadja C
authors.initials: NC
authors.lastname: de Souza-Pinto
authors.affiliation: Homologous Recombination, NHEJ and Maintenance of Genomic Integrity CNRS, UMR7258, Marseille, F-13009, France.|Inserm, U1068, CRCM, Marseille, F-13009, France.|Institut Paoli-Calmettes, Marseille, F-13009, France.
authors.forename: Mauro
authors.initials: M
authors.lastname: Modesti
authors.affiliation: Team DNA Damage Tolerance CNRS, UMR7258, Marseille, F-13009, France.|Inserm, U1068, CRCM, Marseille, F-13009, France.|Institut Paoli-Calmettes, Marseille, F-13009, France.|Aix-Marseille University, UM 105, F-13284, Marseille, France.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Fuchs
authors.affiliation: Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN, 59072-970, Brasil.
authors.forename: Lucymara F
authors.initials: LF
authors.lastname: Agnez-Lima
mesh_terms: D005090:Exodeoxyribonucleases / Q000737:chemistry* / Q000235:genetics*; D015698:Genomic Library; D054892:Metagenome
chemical_list: D005090:Exodeoxyribonucleases
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