Direct Evidence for Packaging Signal-Mediated Assembly of Bacteriophage MS2

Using cross-linking coupled to matrix-assisted laser desorption/ionization mass spectrometry and CLIP-Seq sequencing, we determined the peptide and oligonucleotide sequences at the interfaces between the capsid proteins and the genomic RNA of bacteriophage MS2. The results suggest that the same coat protein (CP)-RNA and maturation protein (MP)-RNA interfaces are used in every viral particle. The portions of the viral RNA in contact with CP subunits span the genome, consistent with a large number of discrete and similar contacts within each particle. Many of these sites match previous predictions of the locations of multiple, dispersed and degenerate RNA sites with cognate CP affinity termed packaging signals (PSs). Chemical RNA footprinting was used to compare the secondary structures of protein-free genomic fragments and the RNA in the virion. Some PSs are partially present in protein-free RNA but others would need to refold from their dominant solution conformations to form the contacts identified in the virion. The RNA-binding peptides within the MP map to two sections of the N-terminal half of the protein. Comparison of MP sequences from related phages suggests a similar arrangement of RNA-binding sites, although these N-terminal regions have only limited sequence conservation. In contrast, the sequences of the C-termini are highly conserved, consistent with them encompassing pilin-binding domains required for initial contact with host cells. These results provide independent and unambiguous support for the assembly of MS2 virions via a PS-mediated mechanism involving a series of induced-fit viral protein interactions with RNA

Acquisition and Evolution of Plant Pathogenesis–Associated Gene Clusters and Candidate Determinants of Tissue-Specificity in Xanthomonas

is a large genus of plant-associated and plant-pathogenic bacteria. Collectively, members cause diseases on over 392 plant species. Individually, they exhibit marked host- and tissue-specificity. The determinants of this specificity are unknown. lineage. genome and indicate that differentiation with respect to host- and tissue-specificity involved not major modifications or wholesale exchange of clusters, but subtle changes in a small number of genes or in non-coding sequences, and/or differences outside the clusters, potentially among regulatory targets or secretory substrates

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Market reforms and public incentives: finding a balance in the Republic of Macedonia

The Republic of Macedonia is undertaking sweeping reforms of its health sector. Funded by a World Bank credit, the reforms seek to improve the efficiency and quality of primary health care (PHC) by significantly strengthening the role of the market in health care provision. On the supply-side, one of the key reform proposals is to implement a capitation payment system for PHC physicians. By placing individual physicians on productivity-based contracts, these reforms will effectively marketize all PHC provision. In addition, the Ministry of Health is considering the sale or concessions of public PHC clinics to private groups, indicating the government's commitment to marketization of health care provision. Macedonia is in a unique position to develop a new role for the private sector in PHC provision. The private provision of outpatient care was legalized soon after independence in 1991; private physicians now account for nearly 10% of all physicians and 22% of PHC physicians. If the reforms are fully realized, all PHC physicians--over 40% of all physicians--will be financially responsible for their clinical practices. This study draws on Macedonia's experience with limited development of private outpatient care starting in 1991 and the reform proposals for PHC, finding a network of policies and procedures throughout the health sector that negatively impact private and public sector provision. An assessment of the effects that this greater policy environment has on private sector provision identifies opportunities to strategically enhance the reforms. With respect to established market economies, the study finds justification for a greater role for government intervention in private health markets in transition economies. In addition to micro-level payment incentives and administrative controls, marketization in Central and Eastern Europe requires an examination of insurance contracting procedures, quality assurance practices, public clinic ownership, referral practices, hospital privileges, and capital investment policies.Private care Reform Primary care Eastern Europe