title: Characterization of a DUF820 family protein Alr3200 of the cyanobacteriumAnabaenasp. strain PCC7120.
abstract: The hypothetical protein 'Alr3200' of Anabaena sp. strain PCC7120 is highly conserved among cyanobacterial species. It is a member of the DUF820 (Domain of Unknown Function) protein family, and is predicted to have a DNase domain. Biochemical analysis revealed a Mg(II)-dependent DNase activity for Alr3200 with a specific activity of 8.62x104 Kunitz Units (KU) mg -1 protein. Circular dichroism analysis predicted Alr3200 to have approximately 40 percent beta-strands and approximately 9 percent alpha-helical structures. Anabaena PCC7120 inherently expressed Alr3200 at very low levels, and its overexpression had no significant effect on growth of Anabaena under control conditions. However, Analr3200+, the recombinant Anabaena strain overexpressing Alr3200, exhibited zero survival upon exposure to 6 kGy of gamma-radiation, which is the LD50 for wild type Anabaena PCC7120 as well as the vector control recombinant strain, AnpAM. Comparative analysis of the two recombinant Anabaena strains suggested that it is not the accumulated Alr3200 per se, but its possible interactions with the radiation-induced unidentified DNA repair proteins of Anabaena, which hampers DNA repair resulting in radiosensitivity.
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.
authors.forename: Prashanth S
authors.initials: PS
authors.lastname: Raghavan
authors.forename: Gagan D
authors.initials: GD
authors.lastname: Gupta
authors.forename: Hema
authors.initials: H
authors.lastname: Rajaram
authors.forename: Vinay
authors.initials: V
authors.lastname: Kumar
mesh_terms: D017033:Anabaena / Q000737:chemistry* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D002942:Circular Dichroism; D004260:DNA Repair / Q000235:genetics; D003851:Deoxyribonucleases / Q000096:biosynthesis / Q000737:chemistry*; D015964:Gene Expression Regulation, Bacterial; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand
chemical_list: D001426:Bacterial Proteins; D003851:Deoxyribonucleases