Solution structure of the DNA-binding domain of RPA from Saccharomyces cerevisiae and its interaction with single-stranded DNA and SV40 T antigen

Replication protein A (RPA) is a three-subunit complex with multiple roles in DNA metabolism. DNA-binding domain A in the large subunit of human RPA (hRPA70A) binds to single-stranded DNA (ssDNA) and is responsible for the species-specific RPA–T antigen (T-ag) interaction required for Simian virus 40 replication. Although Saccharomyces cerevisiae RPA70A (scRPA70A) shares high sequence homology with hRPA70A, the two are not functionally equivalent. To elucidate the similarities and differences between these two homologous proteins, we determined the solution structure of scRPA70A, which closely resembled the structure of hRPA70A. The structure of ssDNA-bound scRPA70A, as simulated by residual dipolar coupling-based homology modeling, suggested that the positioning of the ssDNA is the same for scRPA70A and hRPA70A, although the conformational changes that occur in the two proteins upon ssDNA binding are not identical. NMR titrations of hRPA70A with T-ag showed that the T-ag binding surface is separate from the ssDNA-binding region and is more neutral than the corresponding part of scRPA70A. These differences might account for the species-specific nature of the hRPA70A–T-ag interaction. Our results provide insight into how these two homologous RPA proteins can exhibit functional differences, but still both retain their ability to bind ssDNA

Inhibition of poly(ADP-ribose)polymerase binding to DNA by thymidine dimer

AbstractThe ability of poly(ADP-ribose)polymerase to bind damaged DNA was assessed by electrophoretic mobility shift assay. DNA binding domain of poly(ADP-ribose)polymerase (PARPDBD) binds to synthetic deoxyribonucleotide duplex 10-mer. However, the synthetic deoxyribonucleotide duplex containing cys-syn thymidine dimer which produces the unwinding of DNA helix structure lost its affinity to PARPDBD. It was shown that the binding of PARPDBD to the synthetic deoxyribonucleotide duplex was not affected by O6-Me-dG which causes only minor distortion of DNA helix structure. This study suggests that the stabilized DNA helix structure is important for poly(ADP-ribose)polymerase binding to DNA breaks, which are known to stimulate catalytic activity of poly(ADP-ribose)polymerase

Impact of Depression on Work Productivity and Its Improvement after Outpatient Treatment with Antidepressants

AbstractObjectiveDepressive disorders influence socioeconomic burden at both the individual and organizational levels. This study estimates the lost productive time (LPT) and its resulting cost among workers with major depressive disorder (MDD) compared with a comparison group. It also estimates the change in productivity after 8 weeks of outpatient psychiatric treatment with antidepressants.MethodsWorking patients diagnosed with MDD without other major physical or mental disorders were recruited (n = 102), along with age- and sex-matched healthy controls from the Seoul Metropolitan area (n = 91). The World Health Organization's Health and Work Performance Questionnaire and the Hamilton Rating Scale for Depression were utilized to measure productivity and severity of depression, respectively, at baseline and at 8 weeks of treatment.ResultsThe LPT from absenteeism and presenteeism (reduced performance while present at work) was significantly higher among the MDD group. Workers with MDD averaged costs due to LPT at 33.4% of their average annual salary, whereas the comparison group averaged costs of 2.5% of annual salary. After 8 weeks of treatment, absenteeism and clinical symptoms of depression were significantly reduced and associated with significant improvement in self-rated job performance (31.8%) or cost savings of $7508 per employee per year.ConclusionsWe confirmed that significant productivity loss arises from MDD and that this loss can be reduced with psychiatric intervention after a time period as short as 8 weeks. Mental health professionals should work with employers to devise a cost-effective system to provide workers with accessible quality care

Structure of Influenza A Virus Promoter and its Implications for Viral RNA Synthesis

Since the worst worldwide pandemic ever recorded — the 1918 Spanish influenza outbreak that killed more than 20 million people — we have achieved significant advances in understanding the influenza virus. However, the fear of such a pandemic remains strong. For example, in 1997, when a lethal influenza variant afflicted eight people in Hong Kong, contributing to the death of six, officials feared the next wave had begun. They managed to solve the problem quickly, however, by destroying all of the poultry in Hong Kong[1]

Proton exchange kinetics in [d(ACGTATACGT)]2-echinomycin and [d(ACGTTAACGT)]2-echinomycin complexes

AbstractBased on imino proton exchange catalysis, base-pair lifetimes and apparent dissociation constants are reported on the complexes formed by bisintercalation of echinomycin at the CpG steps of the d(ACGTATACGT)2 and d(ACGTTAACGT)2 duplexes. The lifetimes of the four central A·T base pairs between two echinomycin binding sites are much shorter than in the free duplexes. The destabilization of base pairs adjacent to the binding sites is propagated one additional base pair away from the binding site