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最新一期《美国科学院院刊》文章选读
【字体: 大 中 小 】 时间:2006年06月30日 来源:生物通
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生物通编者按:以下摘选2006年6月27日《美国科学院院刊》(PNAS)的精彩文章。
From the Cover
BIOLOGICAL SCIENCES / PHARMACOLOGY
Discovery of a small-molecule HIV-1 integrase inhibitor-binding site
*Department of Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089;
Edited by Robert A. Lamb, Northwestern University, Evanston, IL, and approved May 15, 2006 (received for review December 28, 2005)
Herein, we report the identification of a unique HIV-1 integrase (IN) inhibitor-binding site using photoaffinity labeling and mass spectrometric analysis. We chemically incorporated a photo-activatable benzophenone moiety into a series of coumarin-containing IN inhibitors. A representative of this series was covalently photo-crosslinked with the IN core domain and subjected to HPLC purification. Fractions were subsequently analyzed by using MALDI-MS and electrospray ionization (ESI)-MS to identify photo-crosslinked products. In this fashion, a single binding site for an inhibitor located within the tryptic peptide 128AACWWAGIK136 was identified. Site-directed mutagenesis followed by in vitro inhibition assays resulted in the identification of two specific amino acid residues, C130 and W132, in which substitutions resulted in a marked resistance to the IN inhibitors. Docking studies suggested a specific disruption in functional oligomeric IN complex formation. The combined approach of photo-affinity labeling/MS analysis with site-directed mutagenesis/molecular modeling is a powerful approach for elucidating inhibitor-binding sites of proteins at the atomic level. This approach is especially important for the study of proteins that are not amenable to traditional x-ray crystallography and NMR techniques. This type of structural information can help illuminate processes of inhibitor resistance and thereby facilitate the design of more potent second-generation inhibitors.
drug design | mass spectrometry | photoaffinity labeling
Nucleophosmin/anaplastic lymphoma kinase (NPM/ALK) oncoprotein induces the T regulatory cell phenotype by activating STAT3
*Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-4283; and
Communicated by Peter C. Nowell, University of Pennsylvania School of Medicine, Philadelphia, PA, April 28, 2006 (received for review March 20, 2006)
The mechanisms of malignant cell transformation mediated by the oncogenic, chimeric nucleophosmin/anaplastic lymphoma kinase (NPM/ALK) tyrosine kinase remain only partially understood. Here we report that the NPM/ALK-carrying T cell lymphoma (ALK+TCL) cells secrete IL-10 and TGF-
cell signaling | immune response evasion | oncogenesis
A Tlr7 translocation accelerates systemic autoimmunity in murine lupus
*Center for Immunology and
Communicated by Diane Mathis, Harvard Medical School, Boston, MA, May 11, 2006 (received for review April 18, 2006)
The y-linked autoimmune accelerating (yaa) locus is a potent autoimmune disease allele. Transcription profiling of yaa-bearing B cells revealed the overexpression of a cluster of X-linked genes that included Tlr7. FISH analysis demonstrated the translocation of this segment onto the yaa chromosome. The resulting overexpression of Tlr7 increased in vitro responses to Toll-like receptor (TLR) 7 signaling in all yaa-bearing males. B6.yaa mice are not overtly autoimmune, but the addition of Sle1, which contains the autoimmune-predisposing Slam/Cd2 haplotype, causes the development of fatal lupus with numerous immunological aberrations. B6.Sle1yaa CD4 T cells develop the molecular signature for TFH cells and also show expression changes in numerous cytokines and chemokines. Disease development and all component autoimmune phenotypes were inhibited by Sles1, a potent suppressor locus. Sles1 had no effect on yaa-enhanced TLR7 signaling in vitro, and these data place Sles1 downstream from the lesion in innate immune responses mediated by TLR7, suggesting that Sles1 modulates the activation of adaptive immunity in response to innate immune signaling.
Sle1 | Sles1 | Toll-like receptor 7 | yaa
Eugenol and isoeugenol, characteristic aromatic constituents of spices, are biosynthesized via reduction of a coniferyl alcohol ester
*Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 830 North University Street, Ann Arbor, MI 48109-1048;
Communicated by Anthony R. Cashmore, University of Pennsylvania, Philadelphia, PA, May 5, 2006 (received for review March 31, 2006)
Phenylpropenes such as chavicol, t-anol, eugenol, and isoeugenol are produced by plants as defense compounds against animals and microorganisms and as floral attractants of pollinators. Moreover, humans have used phenylpropenes since antiquity for food preservation and flavoring and as medicinal agents. Previous research suggested that the phenylpropenes are synthesized in plants from substituted phenylpropenols, although the identity of the enzymes and the nature of the reaction mechanism involved in this transformation have remained obscure. We show here that glandular trichomes of sweet basil (Ocimum basilicum), which synthesize and accumulate phenylpropenes, possess an enzyme that can use coniferyl acetate and NADPH to form eugenol. Petunia (Petunia hybrida cv. Mitchell) flowers, which emit large amounts of isoeugenol, possess an enzyme homologous to the basil eugenol-forming enzyme that also uses coniferyl acetate and NADPH as substrates but catalyzes the formation of isoeugenol. The basil and petunia phenylpropene-forming enzymes belong to a structural family of NADPH-dependent reductases that also includes pinoresinol–lariciresinol reductase, isoflavone reductase, and phenylcoumaran benzylic ether reductase.
floral scent | phenylpropanoids | phenylpropenes | plant volatiles | secondary compounds
Business strategies for conservation on private lands: Koa forestry as a case study
*Interdisciplinary Graduate Program in Environment and Resources, Stanford University, 397 Panama Mall, Mitchell Building, Room B52, Stanford, CA 94305-2210;
Edited by William C. Clark, Harvard University, Cambridge, MA, and approved May 11, 2006 (received for review January 16, 2006)
Innovative financial instruments are being created to reward conservation on private, working lands. Major design challenges remain, however, to make investments in biodiversity and ecosystem services economically attractive and commonplace. From a business perspective, three key financial barriers for advancing conservation land uses must frequently be addressed: high up-front costs, long time periods with no revenue, and high project risk due to long time horizons and uncertainty. We explored ways of overcoming these barriers on grazing lands in Hawaii by realizing a suite of timber and conservation revenue streams associated with their (partial) reforestation. We calculated the financial implications of alternative strategies, focusing on Acacia koa ("koa") forestry because of its high conservation and economic potential. Koa’s timber value alone creates a viable investment (mean net present value = $453/acre), but its long time horizon and poor initial cash flow pose formidable challenges for landowners. At present, subsidy payments from a government conservation program targeting benefits for biodiversity, water quality, and soil erosion have the greatest potential to move landowners beyond the tipping point in favor of investments in koa forestry, particularly when combined with future timber harvest (mean net present value = $1,661/acre). Creating financial mechanisms to capture diverse ecosystem service values through time will broaden opportunities for conservation land uses. Governments, nongovernmental organizations, and private investors have roles to play in catalyzing this transition by developing new revenue streams that can reach a broad spectrum of landowners.