最新一期《美国科学院院刊》文章选读

　　

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

Laith Q. Al-Mawsawi^*, Valery Fikkert^*, Raveendra Dayam^*, Myriam Witvrouw , Terrence R. Burke, Jr. , Christoph H. Borchers ^,¶, and Nouri Neamati^*,¶

*Department of Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089; Division of Molecular Medicine, Katholieke Universiteit Leuven and Interdisciplinary Research Center, Katholieke Universiteit Leuven–Campus Kortrijk, Kapucijnenvoer 33, B-3000 Leuven, Flanders, Belgium; Laboratory of Medicinal Chemistry, Center for Cancer Research, National Institutes of Health, Frederick, MD 21702; and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599

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

Monika Kasprzycka^*, , Michal Marzec^*, Xiaobin Liu^*, Qian Zhang^*, and Mariusz A. Wasik^*,

*Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-4283; and Department of Clinical Immunology, Medical University of Warsaw, 02-006 Warsaw, Poland

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- and express FoxP3, indicating their T regulatory (Treg) cell phenotype. The secreted IL-10 suppresses proliferation of normal immune, CD3/CD28-stimulated peripheral blood mononuclear cells and enhances viability of the ALK+TCL cells. The Treg phenotype of the affected cells is strictly dependent on NPM/ALK expression and function as demonstrated by transfection of the kinase into BaF3 cells and inhibition of its enzymatic activity and expression in ALK+TCL cells. NPM/ALK, in turn, induces the phenotype through activation of its key signal transmitter, signal transducer and activator of transcription 3 (STAT3). These findings identify a mechanism of NPM/ALK-mediated oncogenesis based on induction of the Treg phenotype of the transformed CD4⁺ T cells. These results also provide an additional rationale to therapeutically target the chimeric kinase and/or STAT3 in ALK+TCL.

cell signaling | immune response evasion | oncogenesis

A Tlr7 translocation accelerates systemic autoimmunity in murine lupus

Srividya Subramanian^*, Katalin Tus^*, Quan-Zhen Li^*, Andrew Wang^*, Xiang-Hong Tian^*, Jinchun Zhou^*, Chaoying Liang^*, Guy Bartov , Lisa D. McDaniel , Xin J. Zhou , Roger A. Schultz , and Edward K. Wakeland^*,

*Center for Immunology and Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75235

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 T_FH 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

Takao Koeduka^*, , Eyal Fridman^{*, ,} , David R. Gang ^, , Daniel G. Vassão^¶, Brenda L. Jackson , Christine M. Kish^||, Irina Orlova^||, Snejina M. Spassova^**, Norman G. Lewis^¶, Joseph P. Noel^**, Thomas J. Baiga^**, Natalia Dudareva^||, and Eran Pichersky^*,

*Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 830 North University Street, Ann Arbor, MI 48109-1048; Department of Plant Sciences and Institute for Biomedical Science and Biotechnology, University of Arizona, Tucson, AZ 85721-0036; ^¶Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340; ^||Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907; and **Howard Hughes Medical Institute, Jack H. Skirball Chemical Biology and Proteomics Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037

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

Joshua H. Goldstein^*, , Gretchen C. Daily , James B. Friday , Pamela A. Matson^¶, Rosamond L. Naylor^||, and Peter Vitousek

*Interdisciplinary Graduate Program in Environment and Resources, Stanford University, 397 Panama Mall, Mitchell Building, Room B52, Stanford, CA 94305-2210; Department of Biological Sciences, Stanford University, 371 Serra Mall, Stanford, CA 94305-5020; Department of Natural Resources and Environmental Management, College of Tropical Agriculture and Human Resources, University of Hawaii, 875 Komohana Street, Hilo, HI 96720; ^¶Department of Geological and Environmental Sciences, Stanford University, 327 Panama Mall, Mitchell Building 101, Stanford, CA 94305; and ^||Center for Environmental Science and Policy, Stanford University, Encina Hall E418, Stanford, CA 94305-6055

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.

biodiversity | conservation finance | ecosystem services | Hawaii