Discovery and directed evolution of a glyphosate tolerance gene   总被引：2，自引：0，他引：2  

Castle LA  Siehl DL  Gorton R  Patten PA  Chen YH  Bertain S  Cho HJ  Duck N  Wong J  Liu D  Lassner MW 《Science (New York, N.Y.)》2004,304(5674):1151-1154

The herbicide glyphosate is effectively detoxified by N-acetylation. We screened a collection of microbial isolates and discovered enzymes exhibiting glyphosate N-acetyltransferase (GAT) activity. Kinetic properties of the discovered enzymes were insufficient to confer glyphosate tolerance to transgenic organisms. Eleven iterations of DNA shuffling improved enzyme efficiency by nearly four orders of magnitude from 0.87 mM-1 min-1 to 8320 mM-1 min-1. From the fifth iteration and beyond, GAT enzymes conferred increasing glyphosate tolerance to Escherichia coli, Arabidopsis, tobacco, and maize. Glyphosate acetylation provides an alternative strategy for supporting glyphosate use on crops.  相似文献   

A new strategy for the synthesis of glycoproteins     

Zhang Z  Gildersleeve J  Yang YY  Xu R  Loo JA  Uryu S  Wong CH  Schultz PG 《Science (New York, N.Y.)》2004,303(5656):371-373

Posttranslational modifications of proteins regulate many biological processes, including metabolism, signal transduction, and gene expression. The synthetic challenges associated with generating homogeneous populations of selectively modified proteins, however, have hindered detailed studies of the effects of these modifications on protein structure and function. Here, we report an approach to the cotranslational synthesis of selectively glycosylated proteins in which the modified amino acid is genetically encoded. We show that myoglobin containing beta-N-acetylglucosamine (GlcNAc)-serine at a defined position can be expressed in Escherichia coli in good yield and with high fidelity. The beta-GlcNAc moiety can be recognized by a saccharide-binding protein, or subsequently modified with a galactosyltransferase to build more complex carbohydrates. This approach should be generally applicable to other posttranslational modifications such as protein phosphorylation, acetylation, and methylation.  相似文献   

Reservations about dam findings     

Bain DJ  Smith SM  Nagle GN 《Science (New York, N.Y.)》2008,321(5891):910; author reply 910-910; author reply 912

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Identifying autism loci and genes by tracing recent shared ancestry   总被引：2，自引：0，他引：2  

Morrow EM  Yoo SY  Flavell SW  Kim TK  Lin Y  Hill RS  Mukaddes NM  Balkhy S  Gascon G  Hashmi A  Al-Saad S  Ware J  Joseph RM  Greenblatt R  Gleason D  Ertelt JA  Apse KA  Bodell A  Partlow JN  Barry B  Yao H  Markianos K  Ferland RJ  Greenberg ME  Walsh CA 《Science (New York, N.Y.)》2008,321(5886):218-223

To find inherited causes of autism-spectrum disorders, we studied families in which parents share ancestors, enhancing the role of inherited factors. We mapped several loci, some containing large, inherited, homozygous deletions that are likely mutations. The largest deletions implicated genes, including PCDH10 (protocadherin 10) and DIA1 (deleted in autism1, or c3orf58), whose level of expression changes in response to neuronal activity, a marker of genes involved in synaptic changes that underlie learning. A subset of genes, including NHE9 (Na+/H+ exchanger 9), showed additional potential mutations in patients with unrelated parents. Our findings highlight the utility of "homozygosity mapping" in heterogeneous disorders like autism but also suggest that defective regulation of gene expression after neural activity may be a mechanism common to seemingly diverse autism mutations.  相似文献   

Medicine. The future of personal genomics     

McGuire AL  Cho MK  McGuire SE  Caulfield T 《Science (New York, N.Y.)》2007,317(5845):1687

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Conservation and rewiring of functional modules revealed by an epistasis map in fission yeast     

Roguev A  Bandyopadhyay S  Zofall M  Zhang K  Fischer T  Collins SR  Qu H  Shales M  Park HO  Hayles J  Hoe KL  Kim DU  Ideker T  Grewal SI  Weissman JS  Krogan NJ 《Science (New York, N.Y.)》2008,322(5900):405-410

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Direct measurement of the reaction front in chemically amplified photoresists     

Lin EK  Soles CL  Goldfarb DL  Trinque BC  Burns SD  Jones RL  Lenhart JL  Angelopoulos M  Willson CG  Satija SK  Wu WL 《Science (New York, N.Y.)》2002,297(5580):372-375

The continuing drive by the semiconductor industry to fabricate smaller structures using photolithography will soon require dimensional control at length scales comparable to the size of the polymeric molecules in the materials used to pattern them. The current technology, chemically amplified photoresists, uses a complex reaction-diffusion process to delineate patterned areas with high spatial resolution. However, nanometer-level control of this critical process is limited by the lack of direct measurements of the reaction front. We demonstrate the use of x-ray and neutron reflectometry as a general method to measure the spatial evolution of the reaction-diffusion process with nanometer resolution. Measuring compositional profiles, provided by deuterium-labeled reactant groups for neutron scattering contrast, we show that the reaction front within the material is broad rather than sharply defined and the compositional profile is altered during development. Measuring the density profile, we directly correlate the developed film structure with that of the reaction front.  相似文献   

Crystal structure of a self-spliced group II intron     

Toor N  Keating KS  Taylor SD  Pyle AM 《Science (New York, N.Y.)》2008,320(5872):77-82

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Radioactive elements on Mercury's surface from MESSENGER: implications for the planet's formation and evolution     

Peplowski PN  Evans LG  Hauck SA  McCoy TJ  Boynton WV  Gillis-Davis JJ  Ebel DS  Goldsten JO  Hamara DK  Lawrence DJ  McNutt RL  Nittler LR  Solomon SC  Rhodes EA  Sprague AL  Starr RD  Stockstill-Cahill KR 《Science (New York, N.Y.)》2011,333(6051):1850-1852

The MESSENGER Gamma-Ray Spectrometer measured the average surface abundances of the radioactive elements potassium (K, 1150 ± 220 parts per million), thorium (Th, 220 ± 60 parts per billion), and uranium (U, 90 ± 20 parts per billion) in Mercury's northern hemisphere. The abundance of the moderately volatile element K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme heating of the planet or its precursor materials, and supports formation from volatile-containing material comparable to chondritic meteorites. Abundances of K, Th, and U indicate that internal heat production has declined substantially since Mercury's formation, consistent with widespread volcanism shortly after the end of late heavy bombardment 3.8 billion years ago and limited, isolated volcanic activity since.  相似文献   

Single-cell mass cytometry of differential immune and drug responses across a human hematopoietic continuum     

Bendall SC  Simonds EF  Qiu P  Amir el-AD  Krutzik PO  Finck R  Bruggner RV  Melamed R  Trejo A  Ornatsky OI  Balderas RS  Plevritis SK  Sachs K  Pe'er D  Tanner SD  Nolan GP 《Science (New York, N.Y.)》2011,332(6030):687-696

Flow cytometry is an essential tool for dissecting the functional complexity of hematopoiesis. We used single-cell "mass cytometry" to examine healthy human bone marrow, measuring 34 parameters simultaneously in single cells (binding of 31 antibodies, viability, DNA content, and relative cell size). The signaling behavior of cell subsets spanning a defined hematopoietic hierarchy was monitored with 18 simultaneous markers of functional signaling states perturbed by a set of ex vivo stimuli and inhibitors. The data set allowed for an algorithmically driven assembly of related cell types defined by surface antigen expression, providing a superimposable map of cell signaling responses in combination with drug inhibition. Visualized in this manner, the analysis revealed previously unappreciated instances of both precise signaling responses that were bounded within conventionally defined cell subsets and more continuous phosphorylation responses that crossed cell population boundaries in unexpected manners yet tracked closely with cellular phenotype. Collectively, such single-cell analyses provide system-wide views of immune signaling in healthy human hematopoiesis, against which drug action and disease can be compared for mechanistic studies and pharmacologic intervention.  相似文献