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941.
942.
Christian Linke Paul G. Young Hae Joo Kang Richard D. Bunker Martin J. Middleditch Tom T. Caradoc-Davies Thomas Proft Edward N. Baker 《The Journal of biological chemistry》2010,285(26):20381-20389
Cell surface pili are polymeric protein assemblies that enable bacteria to adhere to surfaces and to specific host tissues. The pili expressed by Gram-positive bacteria constitute a unique paradigm in which sortase-mediated covalent linkages join successive pilin subunits like beads on a string. These pili are formed from two or three distinct types of pilin subunit, typically encoded in small gene clusters, often with their cognate sortases. In Group A streptococci (GAS), a major pilin forms the polymeric backbone, whereas two minor pilins are located at the tip and the base. Here, we report the 1.9-Å resolution crystal structure of the GAS basal pilin FctB, revealing an immunoglobulin (Ig)-like N-terminal domain with an extended proline-rich tail. Unexpected structural homology between the FctB Ig-like domain and the N-terminal domain of the GAS shaft pilin helps explain the use of the same sortase for polymerization of the shaft and its attachment to FctB. It also enabled the identification, from mass spectral data, of the lysine residue involved in the covalent linkage of FctB to the shaft. The proline-rich tail forms a polyproline-II helix that appears to be a common feature of the basal (cell wall-anchoring) pilins. Together, our results indicate distinct structural elements in the pilin proteins that play a role in selecting for the appropriate sortases and thereby help orchestrate the ordered assembly of the pilus. 相似文献
943.
944.
María Fernández-Raga Clemente Tomás Roberto Fraile 《International journal of biometeorology》2010,54(4):379-392
This study was carried out in the region of Castile and Leon, Spain, from 1980 to 1998 and analyzes the relationship between
the number of monthly deaths caused by cardiovascular, respiratory and digestive diseases and three meteorological variables:
temperature, pressure and humidity. One of the innovations in this study is the application of principal component analysis
in a way that differs from its usual application: one single series representing the whole region was constructed for each
meteorological variable from the series of eight weather stations. Annual and seasonal mortality trends were also studied.
Cardiovascular diseases are the leading cause of death in Castile and Leon. The mortality related to cardiovascular, respiratory
and digestive systems shows a statistically significant rising trend across the study period (an annual increase of 6, 16
and 4‰, respectively). The pressure at which mortality is lowest is approximately the same for all causes of death (about
915 hPa), but temperature values vary greatly (16.8–19.7°C for the mean, 10.9–18.1°C for the minimum, and 24.1–27.2°C for
the maximum temperature). The most comfortable temperatures for patients with cardiovascular diseases (16.8°C) are apparently
lower than those for patients with respiratory diseases (18.1°C), which are, in turn, lower than in the case of diseases of
the digestive system (19.7°C). Finally, the optimal humidity for patients with respiratory diseases is the lowest (24%) among
the diseases, and the highest (51%) corresponds to diseases of the digestive system, while the optimal relative humidity for
the cardiovascular system is 45%. 相似文献
945.
Marcio V. B. Dias Fanglu Huang Dimitri Y. Chirgadze Manuela Tosin Dieter Spiteller Emily F. V. Dry Peter F. Leadlay Jonathan B. Spencer Tom L. Blundell 《The Journal of biological chemistry》2010,285(29):22495-22504
The thioesterase FlK from the fluoroacetate-producing Streptomyces cattleya catalyzes the hydrolysis of fluoroacetyl-coenzyme A. This provides an effective self-defense mechanism, preventing any fluoroacetyl-coenzyme A formed from being further metabolized to 4-hydroxy-trans-aconitate, a lethal inhibitor of the tricarboxylic acid cycle. Remarkably, FlK does not accept acetyl-coenzyme A as a substrate. Crystal structure analysis shows that FlK forms a dimer, in which each subunit adopts a hot dog fold as observed for type II thioesterases. Unlike other type II thioesterases, which invariably utilize either an aspartate or a glutamate as catalytic base, we show by site-directed mutagenesis and crystallography that FlK employs a catalytic triad composed of Thr42, His76, and a water molecule, analogous to the Ser/Cys-His-acid triad of type I thioesterases. Structural comparison of FlK complexed with various substrate analogues suggests that the interaction between the fluorine of the substrate and the side chain of Arg120 located opposite to the catalytic triad is essential for correct coordination of the substrate at the active site and therefore accounts for the substrate specificity. 相似文献
946.
Patrick H.C. van Berkel Jolanda Gerritsen Edwin van Voskuilen Gerrard Perdok Tom Vink Jan G.J. van de Winkel Paul W.H.I. Parren 《Biotechnology and bioengineering》2010,105(2):350-357
Rapid production of recombinant human IgG with improved antibody dependent cell‐mediated cytotoxicity (ADCC) effector function is presented. The technique employs transient expression of IgG in suspension growing HEK‐293F cells in the presence of the glycosidase inhibitor kifunensine. The procedure takes ~7 days, provided that expression plasmids encoding the IgG of interest are available. Kifunensine inhibits the N‐linked glycosylation pathway of HEK‐293F cells in the endoplasmatic reticulum, resulting in IgG with oligomannose type glycans lacking core‐fucose. IgG1 transiently produced in kifunensine‐ treated HEK‐293F cells has improved affinity for the FcγRIIIA molecule as measured in an ELISA based assay, and almost eightfold enhanced ADCC using primary peripheral blood mononuclear effector cells. Biotechnol. Bioeng. 2010; 105: 350–357. © 2009 Wiley Periodicals, Inc. 相似文献
947.
RP-HPLC/MS-APCI analysis of odd-chain TAGs from Rhodococcus erythropolis including some regioisomers
Tomáš Řezanka Olga Schreiberová Tereza Krulikovská Jan Masák Karel Sigler 《Chemistry and physics of lipids》2010,163(4-5):373-380
We used reversed phase liquid chromatography–atmospheric pressure chemical ionization mass spectrometry (RP-HPLC/MS-APCI) for direct analysis of triacylglycerols (TAGs) from four different cultivations of Rhodococcus erythropolis CCM 2595. This technique enabled us to identify and quantify the specific molecular species of TAGs directly from lipid extracts of the bacterium, including the determination of their basic characteristics such as retention time and mass spectra. A total of 17 TAGs having at least one odd-numbered-chain FA (fatty acid) were found. This is the first time when odd-chain TAGs, predominantly with pentadecanoic, margaric, and margaroleic acids, were identified. Multiple linear regression analyses were used for predicting retention times of molecular species, predominantly of odd-chain TAGs. Cultivations on two different substrates at two different temperatures (20 and 30 °C) showed that only temperature had any effect on the content of TAGs. In cultivations with succinate as a carbon source the content of these TAGs increased by half (i.e., from 23.5 to 34.2%) when the cultivation temperature was lowered from 30 to 20 °C. The content of the PoPoMo, PoMoO and PPoMo (see Table 1) TAGs containing the odd-numbered-chain margaroleic acid rose from 0.0 to 7.1% while in cultivation on phenol as a carbon source the lowering of cultivation temperature caused an increase of these TAGs from 0.5 to 6.7%. 相似文献
948.
Smith EA Hill K Marlowe F Nolin D Wiessner P Gurven M Bowles S Mulder MB Hertz T Bell A 《Current anthropology》2010,51(1):19-34
We report quantitative estimates of intergenerational transmission and population-wide inequality for wealth measures in a set of hunter-gatherer populations. Wealth is defined broadly as factors that contribute to individual or household well-being, ranging from embodied forms such as weight and hunting success to material forms such household goods, as well as relational wealth in exchange partners. Intergenerational wealth transmission is low to moderate in these populations, but is still expected to have measurable influence on an individual's life chances. Wealth inequality (measured with Gini coefficients) is moderate for most wealth types, matching what qualitative ethnographic research has generally indicated (if not the stereotype of hunter-gatherers as extreme egalitarians). We discuss some plausible mechanisms for these patterns, and suggest ways in which future research could resolve questions about the role of wealth in hunter-gatherer social and economic life. 相似文献
949.
950.