Proteome Organization in a Genome-Reduced Bacterium Kühner, Sebastian; van Noort, Vera; Betts, Matthew J ...
Science (American Association for the Advancement of Science),
11/2009, Letnik:
326, Številka:
5957
Journal Article
Recenzirano
The genome of Mycoplasma pneumoniae is among the smallest found in self-replicating organisms. To study the basic principles of bacterial proteome organization, we used tandem affinity ...purification-mass spectrometry (TAP-MS) in a proteome-wide screen. The analysis revealed 62 homomultimeric and 116 heteromultimeric soluble protein complexes, of which the majority are novel. About a third of the heteromultimeric complexes show higher levels of proteome organization, including assembly into larger, multiprotein complex entities, suggesting sequential steps in biological processes, and extensive sharing of components, implying protein multifunctionality. Incorporation of structural models for 484 proteins, single-particle electron microscopy, and cellular electron tomograms provided supporting structural details for this proteome organization. The data set provides a blueprint of the minimal cellular machinery required for life.
There is a nearly 10,000-year history of human presence in the western Gulf of Alaska, but little understanding of how human foragers integrated into and impacted ecosystems through their roles as ...hunter-gatherers. We present two highly resolved intertidal and nearshore food webs for the Sanak Archipelago in the eastern Aleutian Islands and use them to compare trophic roles of prehistoric humans to other species. We find that the native Aleut people played distinctive roles as super-generalist and highly-omnivorous consumers closely connected to other species. Although the human population was positioned to have strong effects, arrival and presence of Aleut people in the Sanak Archipelago does not appear associated with long-term extinctions. We simulated food web dynamics to explore to what degree introducing a species with trophic roles like those of an Aleut forager, and allowing for variable strong feeding to reflect use of hunting technology, is likely to trigger extinctions. Potential extinctions decreased when an invading omnivorous super-generalist consumer focused strong feeding on decreasing fractions of its possible resources. This study presents the first assessment of the structural roles of humans as consumers within complex ecological networks, and potential impacts of those roles and feeding behavior on associated extinctions.
The type I interferon (IFN) receptor complex is assumed to be composed of multiple protein subunits. Recently, two proteins have been identified as potential receptor components, both of which share ...a high degree of structural homology with the immunoglobulin superfamily. One of these proteins, referred to as the human interferon α receptor (IFNAR), has been shown to be involved in interferon signal transduction, but it does not bind IFN with high affinity. A second putative receptor protein, named FLP40, has been cloned from human Daudi cells. Transfection of FLP40 into murine NIH 3T3 cells does not result in high affinity IFN binding. In this study, we demonstrate that when expressed in murine L929 cells neither IFNAR nor FLP40 by themselves are capable of binding human IFN-α8. Co-expression of IFNAR and FLP40 results in cells capable of binding IFN-α8 and IFN-α2. Scatchard analysis of binding demonstrated the presence of high (KD 350 pM) and low (KD 4.0 nM) affinity binding sites. Binding of radiolabeled IFN-α8 can be competed with either unlabeled IFN-α8 or a recombinant form of human interferon β, IFN-β1b, but not with IFN-g. Ligand binding of IFN-α8 can be inhibited by antibodies directed against IFNAR providing further support for a role for this protein in the formation of a ligand binding site. This is the first demonstration indicating that two previously identified IFN receptor proteins, which individually do not bind type I IFN with high affinity, cooperate in the formation of a type I IFN receptor ligand binding complex.
Recent Books on International Relations Walle, Nicolas van de; Pye, Lucian W; Brown, L. Carl ...
Foreign Affairs,
09/2004, Letnik:
83, Številka:
5
Magazine Article, Book Review
Several books on international relations are reviewed: 1. State-Building: Governance and World Order in the 21st Century by Francis Fukuyama, 2. Final Solutions: Mass Killing and Genocide in the 20th ...Century by Benjamin A. Valentino, 3. From Empire to Community: A New Approach to International Relations by Amitai Etzioni, 4. The Democratic Century by Seymour Martin Lipset and Jason Lakin, 5. Taming the Sovereigns: Institutional Change in International Politics by K. J. Holsti, and 6. Balancing Risks: Great Power Intervention in the Periphery by Jeffrey W. Taliaferro.
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