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201.
The information required for chemical shift assignments in large deuterated proteins was investigated using a Monte Carlo approach (Hitchens et al., 2002). In particular, the consequences of missing amide resonances on the reliability of assignments derived from C and CO or from C and C chemical shifts was investigated. Missing amide resonances reduce both the number of correct assignments as well as the confidence in these assignments. More significantly, a number of undetectable errors can arise when as few as 9% of the amide resonances are missing from the spectra. However, the use of information from residue specific labeling as well as local and long-range distance constraints improves the reliability and extent of assignment. It is also shown that missing residues have only a minor effect on the assignment of protein-ligand complexes using C and CO chemical shifts and C inter-residue connectivity, provided that the known chemical shifts of the unliganded protein are utilized in the assignment process. 相似文献
202.
The crystal structure of a major dust mite allergen Der p 2, and its biological implications 总被引:3,自引:0,他引:3
Derewenda U Li J Derewenda Z Dauter Z Mueller GA Rule GS Benjamin DC 《Journal of molecular biology》2002,318(1):189-197
The crystal structure of the common house mite (Dermatophagoides sp.) Der p 2 allergen was solved at 2.15 A resolution using the MAD phasing technique, and refined to an R-factor of 0.209. The refined atomic model, which reveals an immunoglobulin-like tertiary fold, differs in important ways from the previously described NMR structure, because the two beta-sheets are significantly further apart and create an internal cavity, which is occupied by a hydrophobic ligand. This interaction is structurally reminiscent of the binding of a prenyl group by a regulatory protein, the Rho guanine nucleotide exchange inhibitor. The crystal structure suggests that binding of non-polar molecules may be essential to the physiological function of the Der p 2 protein. 相似文献
203.
Benjamin Cull Joseane Lima Prado Godinho Juliany Cola Fernandes Rodrigues Benjamin Frank Uta Schurigt Roderick AM Williams Graham H Coombs Jeremy C Mottram 《Autophagy》2014,10(12):2143-2157
Autophagy is a central process behind the cellular remodeling that occurs during differentiation of Leishmania, yet the cargo of the protozoan parasite''s autophagosome is unknown. We have identified glycosomes, peroxisome-like organelles that uniquely compartmentalize glycolytic and other metabolic enzymes in Leishmania and other kinetoplastid parasitic protozoa, as autophagosome cargo. It has been proposed that the number of glycosomes and their content change during the Leishmania life cycle as a key adaptation to the different environments encountered. Quantification of RFP-SQL-labeled glycosomes showed that promastigotes of L. major possess ∼20 glycosomes per cell, whereas amastigotes contain ∼10. Glycosome numbers were significantly greater in promastigotes and amastigotes of autophagy-defective L. major Δatg5 mutants, implicating autophagy in glycosome homeostasis and providing a partial explanation for the previously observed growth and virulence defects of these mutants. Use of GFP-ATG8 to label autophagosomes showed glycosomes to be cargo in ∼15% of them; glycosome-containing autophagosomes were trafficked to the lysosome for degradation. The number of autophagosomes increased 10-fold during differentiation, yet the percentage of glycosome-containing autophagosomes remained constant. This indicates that increased turnover of glycosomes was due to an overall increase in autophagy, rather than an upregulation of autophagosomes containing this cargo. Mitophagy of the single mitochondrion was not observed in L. major during normal growth or differentiation; however, mitochondrial remnants resulting from stress-induced fragmentation colocalized with autophagosomes and lysosomes, indicating that autophagy is used to recycle these damaged organelles. These data show that autophagy in Leishmania has a central role not only in maintaining cellular homeostasis and recycling damaged organelles but crucially in the adaptation to environmental change through the turnover of glycosomes. 相似文献
204.
Geographic variation in the ecological effects of extinction of Australia's Pleistocene megafauna 下载免费PDF全文
Chris N. Johnson Susan Rule Simon G. Haberle A. Peter Kershaw G. Merna McKenzie Barry W. Brook 《Ecography》2016,39(2):109-116
Recent studies suggest that extinction of Pleistocene megafauna had large impacts on the structure and functioning of ecosystems, including increased fire and shifts in vegetation state. We argue that the ecological effects of mega‐herbivore extinction are likely to have varied geographically, and might have been reduced in environments of low productivity. We tested this at Caledonia Fen, a cool, high‐elevation site in southeast Australia with a palynological record reaching back approximately 140 ka. The dung fungus Sporormiella indicated that large herbivores were present through most of the early part of the last glacial cycle, but declined abruptly between 50–40 ka and did not recover. This event corresponds with evidence for continent‐wide extinction of Australia's Pleistocene megafauna at that time. An earlier episode of low Sporormiella occurrence coincided with evidence of raised water levels in the fen. Changes in wetland conditions can alter the accumulation of Sporormiella, but there was no such change when Sporormiella counts fell in the period 50–40 ka. We found no evidence that the decline in Sporormiella triggered increased fire or a change in vegetation, which remained a low grass/shrub steppe. This contrasts with a warmer and more humid site, Lynch's Crater in northeast Australia, where decline of dung fungi was followed by increased fire and transition from mixed sclerophyll forest and rainforest to uniform sclerophyll forest. Our results suggest that the magnitude of ecological responses to Pleistocene megafaunal extinction varied geographically, under the control of regional climates. 相似文献
205.
Immunological similarities between specific chloroplast ribosomal proteins from Chlamydomonas reinhardtii and ribosomal proteins from Escherichia coli 总被引:11,自引:0,他引:11
Polyclonal antibodies were elicited against seven of the 33 different
proteins of the large subunit of the chloroplast ribosome from
Chlamydomonas reinhardtii. Three of these proteins are synthesized in the
chloroplast and four are made in the cytoplasm and imported. In western
blots, six of the seven antisera are monospecific for their respective
large subunit ribosomal proteins, and none of these antisera cross-reacted
with any chloroplast small subunit proteins from C. reinhardtii. Antisera
to the three chloroplast-synthesized ribosomal proteins cross-reacted with
specific Escherichia coli large subunit proteins of comparable charge and
molecular weight. Only one of the four antisera to the chloroplast
ribosomal proteins synthesized in the cytoplasm cross-reacted with an E.
coli large subunit protein. None of the antisera cross-reacted with any E.
coli small subunit proteins. On the assumption of a procaryotic,
endosymbiotic origin for the chloroplast, those chloroplast ribosomal
proteins still synthesized within the organelle appear to have retained
more antigenic sites in common with E. coli ribosomal proteins than have
those which are now the products of cytoplasmic protein synthesis. Antisera
to this cytoplasmically synthesized group of chloroplast ribosomal proteins
did not recognize any antigenic sites among C. reinhardtii cytoplasmic
ribosomal proteins, suggesting that the genes for the cytoplasmically
synthesized chloroplast ribosomal proteins either are not derived from the
cytoplasmic ribosomal protein genes or have evolved to a point where no
antigenic similarities remain.
相似文献
206.
Plínio Delatorre Bruno AM Rocha Emmanuel P Souza Taianá M Oliveira Gustavo A Bezerra Frederico BMB Moreno Beatriz T Freitas Tatiane Santi-Gadelha Alexandre H Sampaio Walter F Azevedo Jr Benildo S Cavada 《BMC structural biology》2007,7(1):1-9
Background
Lectins are mainly described as simple carbohydrate-binding proteins. Previous studies have tried to identify other binding sites, which possible recognize plant hormones, secondary metabolites, and isolated amino acid residues. We report the crystal structure of a lectin isolated from Canavalia gladiata seeds (CGL), describing a new binding pocket, which may be related to pathogen resistance activity in ConA-like lectins; a site where a non-protein amino-acid, α-aminobutyric acid (Abu), is bound.Results
The overall structure of native CGL and complexed with α-methyl-mannoside and Abu have been refined at 2.3 Å and 2.31 Å resolution, respectively. Analysis of the electron density maps of the CGL structure shows clearly the presence of Abu, which was confirmed by mass spectrometry.Conclusion
The presence of Abu in a plant lectin structure strongly indicates the ability of lectins on carrying secondary metabolites. Comparison of the amino acids composing the site with other legume lectins revealed that this site is conserved, providing an evidence of the biological relevance of this site. This new action of lectins strengthens their role in defense mechanisms in plants. 相似文献207.
Alpina Begossi Svetlana V Salivonchyk Luciana G Araujo Tainá B Andreoli Mariana Clauzet Claudia M Martinelli Allan GL Ferreira Luiz EC Oliveira Renato AM Silvano 《Journal of ethnobiology and ethnomedicine》2011,7(1):1-23
In this study, we sought to investigate the biology (diet and reproduction) and ethnobiology (fishers knowledge and fishing spots used to catch snappers) of five species of snappers (Lutjanidae), including Lutjanus analis, Lutjanus synagris, Lutjanus vivanus, Ocyurus chrysurus, and Romboplites saliens at five sites along the northeast (Riacho Doce, Maceió in Alagoas State, and Porto do Sauípe, Entre Rios at Bahia State) and the southeast (SE) Brazilian coast (Paraty and Rio de Janeiro cities at Rio de Janeiro State, and Bertioga, at São Paulo State.). We collected 288 snappers and interviewed 86 fishermen. The stomach contents of each fish were examined and macroscopic gonad analysis was performed. Snappers are very important for the fisheries of NE Brazil, and our results indicated that some populations, such as mutton snapper (L. analis) and lane snapper (L. synagris), are being caught when they are too young, at early juvenile stages. Local knowledge has been shown to be a powerful tool for determining appropriate policies regarding management of target species, and artisanal fishermen can be included in management processes. Other suggestions for managing the fisheries are discussed, including proposals that could provide motivation for artisanal fishermen to participate in programs to conserve resources, such as co-management approaches that utilize local knowledge, the establishment of fishing seasons, and compensation of fishermen, through 'payment for environmental services'. These suggestions may enhance the participation of local artisanal fishermen in moving to a more realistic and less top-down management approach of the fish population. 相似文献
208.
E N Amuzu-Aweh P Bijma B P Kinghorn A Vereijken J Visscher J AM van Arendonk H Bovenhuis 《Heredity》2013,111(6):530-538
Prediction of heterosis has a long history with mixed success, partly due to low numbersof genetic markers and/or small data sets. We investigated the prediction of heterosisfor egg number, egg weight and survival days in domestic white Leghorns, using∼400 000 individuals from 47 crosses and allele frequencies on∼53 000 genome-wide single nucleotide polymorphisms (SNPs). When heterosis isdue to dominance, and dominance effects are independent of allele frequencies, heterosisis proportional to the squared difference in allele frequency (SDAF) between parental purelines (not necessarily homozygous). Under these assumptions, a linear model includingregression on SDAF partitions crossbred phenotypes into pure-line values and heterosis,even without pure-line phenotypes. We therefore used models where phenotypes of crossbredswere regressed on the SDAF between parental lines. Accuracy of prediction was determinedusing leave-one-out cross-validation. SDAF predicted heterosis for egg number and weightwith an accuracy of ∼0.5, but did not predict heterosis for survival days. Heterosispredictions allowed preselection of pure lines before field-testing, saving∼50% of field-testing cost with only 4% loss in heterosis. Accuraciesfrom cross-validation were lower than from the model-fit, suggesting that accuraciespreviously reported in literature are overestimated. Cross-validation also indicated thatdominance cannot fully explain heterosis. Nevertheless, the dominance model hadconsiderable accuracy, clearly greater than that of a general/specific combiningability model. This work also showed that heterosis can be modelled even when pure-linephenotypes are unavailable. We concluded that SDAF is a useful predictor of heterosis incommercial layer breeding. 相似文献
209.
210.
Corry-Anke Brandsma Machteld N Hylkema Barry WA van der Strate Dirk-Jan Slebos Marjan A Luinge Marie Geerlings Wim Timens Dirkje S Postma Huib AM Kerstjens 《Respiratory research》2008,9(1):17