Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • Plant disruptors of juvenile hormone receptor [Applied Biological Sciences]
    [Feb 2015]

    Insects impact human health through vector-borne diseases and cause major economic losses by damaging crops and stored agricultural products. Insect-specific growth regulators represent attractive control agents because of their safety to the environment and humans. We identified plant compounds that serve as juvenile hormone antagonists (PJHANs). Using the yeast two-hybrid...
    Categories: Journal Articles
  • Charge disproportionation in perovskite PbCrO3 [Applied Physical Sciences]
    [Feb 2015]

    The perovskite PbCrO3 is an antiferromagnetic insulator. However, the fundamental interactions leading to the insulating state in this single-valent perovskite are unclear. Moreover, the origin of the unprecedented volume drop observed at a modest pressure of P = 1.6 GPa remains an outstanding problem. We report a variety of in...
    Categories: Journal Articles
  • Knot theory realizations in nematic colloids [Applied Physical Sciences]
    [Feb 2015]

    Nematic braids are reconfigurable knots and links formed by the disclination loops that entangle colloidal particles dispersed in a nematic liquid crystal. We focus on entangled nematic disclinations in thin twisted nematic layers stabilized by 2D arrays of colloidal particles that can be controlled with laser tweezers. We take the...
    Categories: Journal Articles
  • Weaponized insulin in cone snail venom [Biochemistry]
    [Feb 2015]

    More than 100 species of venomous cone snails (genus Conus) are highly effective predators of fish. The vast majority of venom components identified and functionally characterized to date are neurotoxins specifically targeted to receptors, ion channels, and transporters in the nervous system of prey, predators, or competitors. Here we describe...
    Categories: Journal Articles
  • Phosphorylation converts Mdm2 to a Nedd8 enzyme [Biochemistry]
    [Feb 2015]

    Murine double minute-2 protein (Mdm2) is a multifaceted phosphorylated protein that plays a role in regulating numerous proteins including the tumor suppressor protein p53. Mdm2 binds to and is involved in conjugating either ubiquitin or Nedd8 (Neural precursor cell expressed, developmentally down-regulated 8) to p53. Although regulation of the E3...
    Categories: Journal Articles
  • Binding of cardiotonic steroids to Na+,K+-ATPase [Biochemistry]
    [Feb 2015]

    Cardiotonic steroids (CTSs) are specific and potent inhibitors of the Na+,K+-ATPase, with highest affinity to the phosphoenzyme (E2P) forms. CTSs are comprised of a steroid core, which can be glycosylated, and a varying number of substituents, including a five- or six-membered lactone. These functionalities have specific influence on the binding...
    Categories: Journal Articles
  • Direct inhibition of KRAS by stapled SOS1 helices [Biochemistry]
    [Feb 2015]

    Activating mutations in the Kirsten rat sarcoma viral oncogene homolog (KRAS) underlie the pathogenesis and chemoresistance of ∼30% of all human tumors, yet the development of high-affinity inhibitors that target the broad range of KRAS mutants remains a formidable challenge. Here, we report the development and validation of stabilized alpha...
    Categories: Journal Articles
  • HCMV gH/gL/gO and Pentamer complexes [Biochemistry]
    [Feb 2015]

    Human cytomegalovirus (HCMV) is a major cause of morbidity and mortality in transplant patients and the leading viral cause of birth defects after congenital infection. The glycoprotein complexes gH/gL/gO and gH/gL/UL128/UL130/UL131A (Pentamer) are key targets of the human humoral response against HCMV and are required for HCMV entry into fibroblasts...
    Categories: Journal Articles
  • IP6K2 promotes cell invasion and tumor metastasis [Cell Biology]
    [Feb 2015]

    The inositol pyrophosphates, molecular messengers containing an energetic pyrophosphate bond, impact a wide range of biologic processes. They are generated primarily by a family of three inositol hexakisphosphate kinases (IP6Ks), the principal product of which is diphosphoinositol pentakisphosphate (IP7). We report that IP6K2, via IP7 synthesis, is a major mediator...
    Categories: Journal Articles
  • p53 controls apoptosis from the ER side [Cell Biology]
    [Feb 2015]

    The tumor suppressor p53 is a key protein in preventing cell transformation and tumor progression. Activated by a variety of stimuli, p53 regulates cell-cycle arrest and apoptosis. Along with its well-documented transcriptional control over cell-death programs within the nucleus, p53 exerts crucial although still poorly understood functions in the cytoplasm,...
    Categories: Journal Articles
  • Regulation of the Hippo pathway by cell junctions [Cell Biology]
    [Feb 2015]

    Adherens junctions (AJs) and cell polarity complexes are key players in the establishment and maintenance of apical–basal cell polarity. Loss of AJs or basolateral polarity components promotes tumor formation and metastasis. Recent studies in vertebrate models show that loss of AJs or loss of the basolateral component Scribble (Scrib) cause...
    Categories: Journal Articles
  • Metal-free sensitizers for water splitting [Chemistry]
    [Feb 2015]

    Solar fuel generation requires the efficient capture and conversion of visible light. In both natural and artificial systems, molecular sensitizers can be tuned to capture, convert, and transfer visible light energy. We demonstrate that a series of metal-free porphyrins can drive photoelectrochemical water splitting under broadband and red light (λ...
    Categories: Journal Articles
  • Reversible catalytic dehydrogenation of alcohols [Chemistry]
    [Feb 2015]

    Reversibility of a dehydrogenation/hydrogenation catalytic reaction has been an elusive target for homogeneous catalysis. In this report, reversible acceptorless dehydrogenation of secondary alcohols and diols on iron pincer complexes and reversible oxidative dehydrogenation of primary alcohols/reduction of aldehydes with separate transfer of protons and electrons on iridium complexes are shown....
    Categories: Journal Articles
  • Quinary structure and protein stability [Chemistry]
    [Feb 2015]

    Protein quinary interactions organize the cellular interior and its metabolism. Although the interactions stabilizing secondary, tertiary, and quaternary protein structure are well defined, details about the protein–matrix contacts that comprise quinary structure remain elusive. This gap exists because proteins function in the crowded cellular environment, but are traditionally studied in...
    Categories: Journal Articles
  • Chemical signature of magnetotactic bacteria [Earth, Atmospheric, and Planetary Sciences]
    [Feb 2015]

    There are longstanding and ongoing controversies about the abiotic or biological origin of nanocrystals of magnetite. On Earth, magnetotactic bacteria perform biomineralization of intracellular magnetite nanoparticles under a controlled pathway. These bacteria are ubiquitous in modern natural environments. However, their identification in ancient geological material remains challenging. Together with physical...
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  • Fronts drive fishery production [Ecology]
    [Feb 2015]

    Long-term changes in nutrient supply and primary production reportedly foreshadow substantial declines in global marine fishery production. These declines combined with current overfishing, habitat degradation, and pollution paint a grim picture for the future of marine fisheries and ecosystems. However, current models forecasting such declines do not account for the...
    Categories: Journal Articles
  • Parasitism alters three power laws of scaling [Ecology]
    [Feb 2015]

    How do the lifestyles (free-living unparasitized, free-living parasitized, and parasitic) of animal species affect major ecological power-law relationships? We investigated this question in metazoan communities in lakes of Otago, New Zealand. In 13,752 samples comprising 1,037,058 organisms, we found that species of different lifestyles differed in taxonomic distribution and body...
    Categories: Journal Articles
  • Optical antenna enhanced spontaneous emission [Engineering]
    [Feb 2015]

    Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at...
    Categories: Journal Articles
  • Natural variation in fitness [Evolution]
    [Feb 2015]

    DNA sequencing has revealed high levels of variability within most species. Statistical methods based on population genetics theory have been applied to the resulting data and suggest that most mutations affecting functionally important sequences are deleterious but subject to very weak selection. Quantitative genetic studies have provided information on the...
    Categories: Journal Articles
  • Protein folding and binding evolve as spandrels [Evolution]
    [Feb 2015]

    Binding interactions between proteins and other molecules mediate numerous cellular processes, including metabolism, signaling, and gene regulation. These interactions often evolve in response to changes in the protein’s chemical or physical environment (such as the addition of an antibiotic). Several recent studies have shown the importance of folding stability in...
    Categories: Journal Articles