title: Retracted: Nuclear localization and in situ DNA damage by Mycobacterium tuberculosis nucleoside-diphosphate kinase.
abstract: Nucleoside-diphosphate kinase of Mycobacterium tuberculosis (mNdK) is a secretory protein, but the rationale behind secreting an enzyme involved in the maintenance of cellular pool of nucleoside triphosphates is not clearly understood. To elucidate the biological significance of mNdK secretion, we expressed mNdK fused to green fluorescent protein in HeLa and COS-1 cells. Interestingly, mNdK was detected in the nuclei of HeLa and COS-1 cells. Incubation of mNdK with nuclei isolated from HeLa and COS-1 cells led to in situ damage of chromosomal DNA. Surface plasmon resonance studies demonstrated that mNdK binds supercoiled plasmid DNA lacking apurinic/apyrimidinic sites with a dissociation constant of 30 +/- 3.2 mum. Plasmid cleavage by mNdK was found to be dependent on the specific divalent metal ion and inhibited by a metal ion chelator. Moreover, the metal ion-dependent DNA cleavage by mNdK was mediated by superoxide radicals as detected by electron paramagnetic resonance. The cleavage reaction was inhibited under nitrogen atmosphere confirming the necessity of molecular oxygen for DNA cleavage. In view of the findings that mNdK is secreted by intracellular mycobacteria and damages the nuclear DNA, it can be postulated that mNdK may cause cell death that could help in the dissemination of the pathogen.
authors.affiliation: Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi 110 007, India.
authors.forename: Adesh Kumar
authors.initials: AK
authors.lastname: Saini
authors.forename: Kapil
authors.initials: K
authors.lastname: Maithal
authors.forename: Prem
authors.initials: P
authors.lastname: Chand
authors.forename: Shantanu
authors.initials: S
authors.lastname: Chowdhury
authors.forename: Reena
authors.initials: R
authors.lastname: Vohra
authors.forename: Anita
authors.initials: A
authors.lastname: Goyal
authors.forename: Gyanendra P
authors.initials: GP
authors.lastname: Dubey
authors.forename: Puneet
authors.initials: P
authors.lastname: Chopra
authors.forename: Ramesh
authors.initials: R
authors.lastname: Chandra
authors.forename: Anil K
authors.initials: AK
authors.lastname: Tyagi
authors.forename: Yogendra
authors.initials: Y
authors.lastname: Singh
authors.forename: Vibha
authors.initials: V
authors.lastname: Tandon
mesh_terms: D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000378:metabolism; D017124:Conserved Sequence; D004247:DNA / Q000378:metabolism*; D004249:DNA Damage / Q000502:physiology; D006801:Humans; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000378:metabolism; D009701:Nucleoside-Diphosphate Kinase / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D020539:Sequence Analysis, Protein; D013997:Time Factors
chemical_list: D004247:DNA; D009701:Nucleoside-Diphosphate Kinase