Impairment of the non-catalytic subunit Dpb2 of DNA Pol ɛ results in increased involvement of Pol δ on the leading strand

The generally accepted model assumes that leading strand synthesis is performed by Pol ε, while lagging-strand synthesis is catalyzed by Pol δ. Pol ε has been shown to target the leading strand by interacting with the CMG helicase [Cdc45 Mcm2-7 GINS(Psf1-3, Sld5)]. Proper functioning of the CMG-Pol ɛ, the helicase-polymerase complex is essential for its progression and the fidelity of DNA replication. Dpb2p, the essential non-catalytic subunit of Pol ε plays a key role in maintaining the correct architecture of the replisome by acting as a link between Pol ε and the CMG complex. Using a temperature-sensitive dpb2-100 mutant previously isolated in our laboratory, and a genetic system which takes advantage of a distinct mutational signature of the Pol δ-L612M variant which allows detection of the involvement of Pol δ in the replication of particular DNA strands we show that in yeast cells with an impaired Dpb2 subunit, the contribution of Pol δ to the replication of the leading strand is significantly increased.

Recombination and Pol ζ Rescue Defective DNA Replication upon Impaired CMG Helicase-Pol ε Interaction

The CMG complex (Cdc45, Mcm2–7, GINS (Psf1, 2, 3, and Sld5)) is crucial for both DNA replication initiation and fork progression. The CMG helicase interaction with the leading strand DNA polymerase epsilon (Pol ε) is essential for the preferential loading of Pol ε onto the leading strand, the stimulation of the polymerase, and the modulation of helicase activity. Here, we analyze the consequences of impaired interaction between Pol ε and GINS in Saccharomyces cerevisiae cells with the psf1-100 mutation. This significantly affects DNA replication activity measured in vitro, while in vivo, the psf1-100 mutation reduces replication fidelity by increasing slippage of Pol ε, which manifests as an elevated number of frameshifts. It also increases the occurrence of single-stranded DNA (ssDNA) gaps and the demand for homologous recombination. The psf1-100 mutant shows elevated recombination rates and synthetic lethality with rad52Δ. Additionally, we observe increased participation of DNA polymerase zeta (Pol ζ) in DNA synthesis. We conclude that the impaired interaction between GINS and Pol ε requires enhanced involvement of error-prone Pol ζ, and increased participation of recombination as a rescue mechanism for recovery of impaired replication forks.

Mapping of the interactions between partition proteins Delta and Omega of plasmid pSM19035 from Streptococcus pyogenes

Formation of the segrosome, a nucleoprotein complex crucial for proper functioning of plasmid partition systems, involves interactions between specific partition proteins (ParA-like and ParB-like), ATP and specific DNA sequences (the centromeric sites). Although partition systems have been studied for many years, details of the segrosome formation are not yet clear. Organization of the pSM19035-encoded partition system is unique; in contrast with other known par systems, here, the δ and ω genes do not constitute an operon. Moreover, Omega [a ParB-like protein which has a Ribbon-Helix-Helix (RHH) structure] recognizes multiple centromeric sequences located in the promoters of δ, ω and copS (copy-number control gene). The ParA-like protein Delta is a Walker-type ATPase. In this work, we identify the interaction domains and requirements for dimerization and hetero-interactions of the Delta and Omega proteins of pSM19035 plasmid. The RHH structures are involved in Omega dimerization in vivo and its N-terminal unstructured part is indispensable for association with Delta, both in vivo and in vitro. Omega does not need to form dimers to interact with Delta. ATP binding is not required for Delta dimerization but is important for interaction with Omega in vivo. The in vitro interaction between Delta and Omega depends on ATP but does not require the presence of specific DNA segments (the centromere) recognized by Omega. The C-terminal part of the Delta protein (aa 198-284) is indispensable for interaction with Omega. Delta most probably interacts with Omega as a dimer since two amino acid substitutions in a conserved region between the A' and B motifs abolish both the dimerization of Delta and its interaction with Omega.

Poland health system review

Since the successful transition to a freely elected parliament and a market economy after 1989, Poland is now a stable democracy and is well represented within political and economic organizations in Europe and worldwide. The strongly centralized health system based on the Semashko model was replaced with a decentralized system of mandatory health insurance, complemented with financing from state and territorial self-government budgets. There is a clear separation of health care financing and provision: the National Health Fund (NFZ) the sole payer in the system is in charge of health care financing and contracts with public and non-public health care providers. The Ministry of Health is the key policy-maker and regulator in the system and is supported by a number of advisory bodies, some of them recently established. Health insurance contributions, borne entirely by employees, are collected by intermediary institutions and are pooled by the NFZ and distributed between the 16 regional NFZ branches. In 2009, Poland spent 7.4% of its gross domestic product (GDP) on health. Around 70% of health expenditure came from public sources and over 83.5% of this expenditure can be attributed to the (near) universal health insurance. The relatively high share of private expenditure is mostly represented by out-of-pocket (OOP) payments, mainly in the form of co-payments and informal payments. Voluntary health insurance (VHI) does not play an important role and is largely limited to medical subscription packages offered by employers. Compulsory health insurance covers 98% of the population and guarantees access to a broad range of health services. However, the limited financial resources of the NFZ mean that broad entitlements guaranteed on paper are not always available. Health care financing is overall at most proportional: while financing from health care contributions is proportional and budgetary subsidies to system funding are progressive, high OOP expenditures, particularly in areas such as pharmaceuticals, are highly regressive. The health status of the Polish population has improved substantially, with average life expectancy at birth reaching 80.2 years for women and 71.6 years for men in 2009. However, there is still a vast gap in life expectancy between Poland and the western European Union (EU) countries and between life expectancy overall and the expected number of years without illness or disability. Given its modest financial, human and material health care resources and the corresponding outcomes, the overall financial efficiency of the Polish system is satisfactory. Both allocative and technical efficiency leave room for improvement. Several measures, such as prioritizing primary care and adopting new payment mechanisms such as diagnosis-related groups (DRGs), have been introduced in recent years but need to be expanded to other areas and intensified. Additionally, numerous initiatives to enhance quality control and build the required expertise and evidence base for the system are also in place. These could improve general satisfaction with the system, which is not particularly high. Limited resources, a general aversion to cost-sharing stemming from a long experience with broad public coverage and shortages in health workforce need to be addressed before better outcomes can be achieved by the system. Increased cooperation between various bodies within the health and social care sectors would also contribute in this direction. The HiT profiles are country-based reports that provide a detailed description of a health system and of policy initiatives in progress or under development. HiTs examine different approaches to the organization, financing and delivery of health services, and the role of the main actors in health systems; they describe the institutional framework, process, content and implementation of health and health care policies; and highlight challenges and areas that require more in-depth analysis.

Characterization of a novel partition system encoded by the delta and omega genes from the streptococcal plasmid pSM19035

High segregational stability of the streptococcal plasmid pSM19035 is achieved by the concerted action of systems involved in plasmid copy number control, multimer resolution, and postsegregational killing. In this study, we demonstrate the role of two genes, delta and omega, in plasmid stabilization by a partition mechanism. We show that these two genes can stabilize the native pSM19035 replicon as well as other theta- and sigma-type plasmids in Bacillus subtilis. In contrast to other known partition systems, in this case the two genes are transcribed separately; however, they are coregulated by the product of the parB-like gene omega. Analysis of mutants of the parA-like gene delta showed that the Walker A ATPase motif is necessary for plasmid stabilization. The ParB-like product of the omega gene binds to three regions containing repeated WATCACW heptamers, localized in the copS (regulation of plasmid copy number), delta, and omega promoter regions. We demonstrate that all three of these regions can cause partition-mediated incompatibility. Moreover, our data suggest that each of these could play the role of a centromere-like sequence. We conclude that delta and omega constitute a novel type of plasmid stabilization system.