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New insights into the GINS complex explain the controversy between existing structural models.

ABSTRACT: GINS is a key component of eukaryotic replicative forks and is composed of four subunits (Sld5, Psf1, Psf2, Psf3). To explain the discrepancy between structural data from crystallography and electron microscopy (EM), we show that GINS is a compact tetramer in solution as observed in crystal structures, but also forms a double-tetrameric population, detectable by EM. This may represent an intermediate step towards the assembly of two replicative helicase complexes at origins, moving in opposite directions within the replication bubble. Reconstruction of the double-tetrameric form, combined with small-angle X-ray scattering data, allows the localisation of the B domain of the Psf1 subunit in the free GINS complex, which was not visible in previous studies and is essential for the formation of a functional replication fork.

SUBMITTER: Carroni M

PROVIDER: S-EPMC5223209 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature

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New insights into the GINS complex explain the controversy between existing structural models.

Carroni Marta M De March Matteo M Medagli Barbara B Krastanova Ivet I Taylor Ian A IA Amenitsch Heinz H Araki Hiroyuchi H Pisani Francesca M FM Patwardhan Ardan A Onesti Silvia S

Scientific reports 20170110

GINS is a key component of eukaryotic replicative forks and is composed of four subunits (Sld5, Psf1, Psf2, Psf3). To explain the discrepancy between structural data from crystallography and electron microscopy (EM), we show that GINS is a compact tetramer in solution as observed in crystal structures, but also forms a double-tetrameric population, detectable by EM. This may represent an intermediate step towards the assembly of two replicative helicase complexes at origins, moving in opposite d ...[more]

PMID: 28071757

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Project description:BACKGROUND:Malaria is one of the strongest recent selective pressures on the human genome, as evidenced by the high levels of varying haemoglobinopathies in human populations-despite the increased risk of mortality in the homozygous states. Previously, functional polymorphisms of Hp, coded by the co-dominant alleles Hp1 and Hp2, have been variously associated with several infectious diseases, including malaria susceptibility. METHODOLOGY/PRINCIPAL FINDINGS:Risk of a clinical malarial episode over the course of a malarial transmission season was assessed using active surveillance in a cohort of Gambian children aged 10-72 months. We report for the first time that the major haplotype for the A-61C mutant allele in the promoter of haptoglobin (Hp)-an acute phase protein that clears haemoglobin released from haemolysis of red cells-is associated with protection from malarial infection in older children, (children aged >or=36 months, >500 parasites/ul and temperature >37.5 degrees C; OR = 0.42; [95% CI 0.24-0.73] p = 0.002) (lr test for interaction, <36 vs >or=36 months, p = 0.014). Protection was also observed using two other definitions, including temperature >37.5 degrees C, dipstick positive, plus clinical judgement of malaria blinded to dipstick result (all ages, OR = 0.48, [95% CI 0.30-0.78] p = 0.003; >or=36 months, OR = 0.31, [95% CI 0.15-0.62] p = 0.001). A similar level of protection was observed for the known protective genetic variant, sickle cell trait (HbAS). CONCLUSIONS/SIGNIFICANCE:We propose that previous conflicting results between Hp phenotypes/genotypes and malaria susceptibility may be explained by differing prevalence of the A-61C SNP in the populations studied, which we found to be highly associated with the Hp2 allele. We report the -61C allele to be associated with decreased Hp protein levels (independent of Hp phenotype), confirming in vitro studies. Decreased Hp expression may lead to increased oxidant stress and increased red cell turnover, and facilitate the development of acquired immunity, similar to a mechanism suggested for sickle cell trait.

Dataset Information

New insights into the GINS complex explain the controversy between existing structural models.

Publications

New insights into the GINS complex explain the controversy between existing structural models.

Similar Datasets

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