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排序方式: 共有1005条查询结果,搜索用时 15 毫秒
161.
Ping Li Niloofar Nayeri Kamil Grecki Eva Ramos Becares Kaituo Wang Dhani Ram Mahato Magnus Andersson Sameera S. Abeyrathna Karin LindkvistPetersson Gabriele Meloni Julie Winkel Missel Pontus Gourdon 《Protein science : a publication of the Protein Society》2022,31(7)
Copper (Cu) is one of the most abundant trace metals in all organisms, involved in a plethora of cellular processes. Yet elevated concentrations of the element are harmful, and interestingly prokaryotes are more sensitive for environmental Cu stress than humans. Various transport systems are present to maintain intracellular Cu homeostasis, including the prokaryotic plasmid‐encoded multiprotein pco operon, which is generally assigned as a defense mechanism against elevated Cu concentrations. Here we structurally and functionally characterize the outer membrane component of the Pco system, PcoB, recovering a 2.0 Å structure, revealing a classical β‐barrel architecture. Unexpectedly, we identify a large opening on the extracellular side, linked to a considerably electronegative funnel that becomes narrower towards the periplasm, defining an ion‐conducting pathway as also supported by metal binding quantification via inductively coupled plasma mass spectrometry and molecular dynamics (MD) simulations. However, the structure is partially obstructed towards the periplasmic side, and yet flux is permitted in the presence of a Cu gradient as shown by functional characterization in vitro. Complementary in vivo experiments demonstrate that isolated PcoB confers increased sensitivity towards Cu. Aggregated, our findings indicate that PcoB serves to permit Cu import. Thus, it is possible the Pco system physiologically accumulates Cu in the periplasm as a part of an unorthodox defense mechanism against metal stress. These results point to a previously unrecognized principle of maintaining Cu homeostasis and may as such also assist in the understanding and in efforts towards combatting bacterial infections of Pco‐harboring pathogens. 相似文献
162.
Jia Xuan Leong Margot Raffeiner Daniela Spinti Gautier Langin Mirita FranzWachtel Andrew R Guzman JungGun Kim Pooja Pandey Alyona E Minina Boris Macek Anders Hafrn Tolga O Bozkurt Mary Beth Mudgett Frederik Brnke Daniel Hofius Suayib Üstün 《The EMBO journal》2022,41(13)
Beyond its role in cellular homeostasis, autophagy plays anti‐ and promicrobial roles in host–microbe interactions, both in animals and plants. One prominent role of antimicrobial autophagy is to degrade intracellular pathogens or microbial molecules, in a process termed xenophagy. Consequently, microbes evolved mechanisms to hijack or modulate autophagy to escape elimination. Although well‐described in animals, the extent to which xenophagy contributes to plant–bacteria interactions remains unknown. Here, we provide evidence that Xanthomonas campestris pv. vesicatoria (Xcv) suppresses host autophagy by utilizing type‐III effector XopL. XopL interacts with and degrades the autophagy component SH3P2 via its E3 ligase activity to promote infection. Intriguingly, XopL is targeted for degradation by defense‐related selective autophagy mediated by NBR1/Joka2, revealing a complex antagonistic interplay between XopL and the host autophagy machinery. Our results implicate plant antimicrobial autophagy in the depletion of a bacterial virulence factor and unravel an unprecedented pathogen strategy to counteract defense‐related autophagy in plant–bacteria interactions. 相似文献
163.
2005年4--5月、6--7月、10--11月笔者在浙江省舟山市嵊泗县大洋山岛(中心点坐标30°34′N,122°4′E进行鸟类调相过程中,记录到日本淡脚柳莺(Phylloscopus borealoides)和硫磺(巫鸟)(Emberiza sulphurata),经查阅相关文献后确认为浙江省鸟类新记录.现报道如下: 相似文献
164.
Phosphorus Limitation in Boreal Forests: Effects of Aluminum and Iron Accumulation in the Humus Layer 总被引:1,自引:1,他引:1
Plant growth in boreal forests is generally considered to be predominantly nitrogen (N) limited, but forested groundwater
discharge areas may be exceptions. In this study, we conducted tests to determine whether highly productive forested groundwater
discharge areas generally differ from adjacent groundwater recharge areas in terms of humus chemistry and the availability
of phosphorus (P) and N to plants. We investigated six forested sites, divided into groundwater discharge and adjacent groundwater
recharge areas, in northern Sweden. The humus layers of the forested groundwater discharge areas were clearly distinguished
from the adjacent groundwater recharge areas by having higher acid-digestible calcium (Ca) and/or aluminium (Al) and iron
(Fe) content and higher organic P and N content. Soil solution inorganic N (NH4
+ and NO3
−) and pH were higher in the groundwater discharge areas than in the groundwater recharge areas. The organic P content showed
a positive linear relationship to the Al and Fe content in the humus layer, indicating that organic P is associated with Al
and Fe compounds in the humus. A plant bioassay using humus substrate from one groundwater discharge area and the adjacent
groundwater recharge area found that plants grown in groundwater discharge area humus (with a high P-fixation capacity) increased
their biomass upon P fertilization, whereas no growth response was found for N additions. By contrast, plants grown in humus
from the groundwater recharge area did not respond to added P unless N was added too. This study suggests that groundwater
discharge can affect the nutrient availability of N and P both directly, via increased P fixation due to the redistribution
of Al and Fe, and indirectly, via the inflow of groundwater high in Ca and alkalinity, maintaining a high pH in the humus
layer that favors in situ N turnover processes.
Received 2 March 2001; Accepted 9 November 2001. 相似文献
165.
Heroen Verbruggen † Lennert Tyberghein † Klaas Pauly † Caroline Vlaeminck Katrien Van Nieuwenhuyze Wiebe H.C.F. Kooistra Frederik Leliaert Olivier De Clerck 《Global Ecology and Biogeography》2009,18(4):393-405
Aim Because of their broad distribution in geographical and ecological dimensions, seaweeds (marine macroalgae) offer great potential as models for marine biogeographical inquiry and exploration of the interface between macroecology and macroevolution. This study aims to characterize evolutionary niche dynamics in the common green seaweed genus Halimeda, use the observed insights to gain understanding of the biogeographical history of the genus and predict habitats that can be targeted for the discovery of species of special biogeographical interest. Location Tropical and subtropical coastal waters. Methods The evolutionary history of the genus is characterized using molecular phylogenetics and relaxed molecular clock analysis. Niche modelling is carried out with maximum entropy techniques and uses macroecological data derived from global satellite imagery. Evolutionary niche dynamics are inferred through application of ancestral character state estimation. Results A nearly comprehensive molecular phylogeny of the genus was inferred from a six‐locus dataset. Macroecological niche models showed that species distribution ranges are considerably smaller than their potential ranges. We show strong phylogenetic signal in various macroecological niche features. Main conclusions The evolution of Halimeda is characterized by conservatism for tropical, nutrient‐depleted habitats, yet one section of the genus managed to invade colder habitats multiple times independently. Niche models indicate that the restricted geographical ranges of Halimeda species are not due to habitat unsuitability, strengthening the case for dispersal limitation. Niche models identified hotspots of habitat suitability of Caribbean species in the eastern Pacific Ocean. We propose that these hotspots be targeted for discovery of new species separated from their Caribbean siblings since the Pliocene rise of the Central American Isthmus. 相似文献
166.
Hammes F Broger T Weilenmann HU Vital M Helbing J Bosshart U Huber P Odermatt RP Sonnleitner B 《Cytometry. Part A》2012,81(6):508-516
Accurate and sensitive online detection tools would benefit both fundamental research and practical applications in aquatic microbiology. Here, we describe the development and testing of an online flow cytometer (FCM), with a specific use foreseen in the field of drinking water microbiology. The system incorporated fully automated sampling and fluorescent labeling of bacterial nucleic acids with analysis at 5-min intervals for periods in excess of 24 h. The laboratory scale testing showed sensitive detection (< 5% error) of bacteria over a broad concentration range (1 × 10(3) -1 × 10(6) cells mL(-1) ) and particularly the ability to track both gradual changes and dramatic events in water samples. The system was tested with bacterial pure cultures as well as indigenous microbial communities from natural water samples. Moreover, we demonstrated the possibility of using either a single fluorescent dye (e.g., SYBR Green I) or a combination of two dyes (SYBR Green I and Propidium Iodide), thus broadening the application possibilities of the system. The online FCM approach described herein has considerable potential for routine and continuous monitoring of drinking water, optimization of specific drinking water processes such as biofiltration or disinfection, as well as aquatic microbiology research in general. 相似文献
167.
Xu J Reumers J Couceiro JR De Smet F Gallardo R Rudyak S Cornelis A Rozenski J Zwolinska A Marine JC Lambrechts D Suh YA Rousseau F Schymkowitz J 《Nature chemical biology》2011,7(5):285-295
Many p53 missense mutations possess dominant-negative activity and oncogenic gain of function. We report that for structurally destabilized p53 mutants, these effects result from mutant-induced coaggregation of wild-type p53 and its paralogs p63 and p73, thereby also inducing a heat-shock response. Aggregation of mutant p53 resulted from self-assembly of a conserved aggregation-nucleating sequence within the hydrophobic core of the DNA-binding domain, which becomes exposed after mutation. Suppressing the aggregation propensity of this sequence by mutagenesis abrogated gain of function and restored activity of wild-type p53 and its paralogs. In the p53 germline mutation database, tumors carrying aggregation-prone p53 mutations have a significantly lower frequency of wild-type allele loss as compared to tumors harboring nonaggregating mutations, suggesting a difference in clonal selection of aggregating mutants. Overall, our study reveals a novel disease mechanism for mutant p53 gain of function and suggests that, at least in some respects, cancer could be considered an aggregation-associated disease. 相似文献
168.
169.
Prevalence of ESR1 amplification in breast cancer is highly disputed and discrepancies have been related to different technical protocols and different scoring approaches. In addition, pre-mRNA artifacts have been proposed to influence outcome of ESR1 FISH analysis. We analyzed ESR1 gene copy number status combining an improved RNase FISH protocol with multiplex ligation-dependent probe amplification (MLPA) after laser microdissection. FISH showed a high prevalence of ESR1 gains and amplifications despite RNase treatment but MLPA did not confirm ESR1 copy number increases detected by FISH in more than half of cases. We suggest that the combination of the ESR1-specific intra-tumor heterogeneity and low-level copy number increase accounts for these discrepancies. 相似文献
170.
Frederik D. Weber 《Current biology : CB》2018,28(5):R217-R220