共查询到20条相似文献,搜索用时 0 毫秒
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A protective organelle that is essential for viability under most conditions, the cell wall is a dynamic structure that is continuously remodelled with the growth of the bacterial cell. Because the cell wall also moulds the bacterium, the mechanisms of cell wall homeostasis can be deciphered using cell shape as a convenient proxy. In this issue of Molecular Microbiology, Foulquier et al. illuminate a connection between cell shape regulation and metabolism in Bacillus subtilis. They find that the putative NAD(P)‐binding enzyme YvcK organizes into helical subcellular structures that exert shape control by directing the cell wall biosynthetic enzyme PBP1 along the cell cylinder and to the septum, a function shared with the MreB actin cytoskeleton. Unlike MreB, however, the role of YvcK in cell shape control is manifested only on certain carbon sources, presumably by way of a previously unknown metabolic feed that taps into cell morphogenesis. 相似文献
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Davies AM 《Current biology : CB》2000,10(10):R374-R376
NGF's role in neuronal survival has tended to mask other potential functions. But now the generation of mice lacking both Bax - required for the death of NGF-deprived neurons - and NGF or its receptor has shown that NGF plays a key role in establishing cutaneous innervation and regulating neuropeptide expression. 相似文献
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Hull CM 《Cell host & microbe》2011,9(3):174-175
While a polysaccharide capsule is known to be important for preventing phagocytosis of the human pathogen Cryptococcus neoformans, other antiphagocytic pathways have been generally elusive. Now, a capsule-independent pathway has been identified that prevents macrophages from ingesting the fungus, contributing to evasion of the host immune response. 相似文献
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Dale L 《Current biology : CB》2000,10(18):R671-R673
Dorsal-ventral patterning in Xenopus and Drosophila embryos involves BMP family signalling molecules. Twisted Gastrulation has now been added to the list of proteins that regulate the activity of these molecules, providing new insights into how BMPs are made available to their signalling receptors. 相似文献
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Recent studies of the bacterial mechanosensitive channel MscL have combined a number of different approaches to come up with a model for the channel gating mechanism. 相似文献
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Much of the effort in understanding the dynamic process of development has focused on dissecting biochemical pathways. Recent studies illustrate that simple physical forces are also important in patterning organs. 相似文献
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Batesian mimics are predicted to lose their fitness advantage not only in the absence of an unpalatable model, but also when the mimic becomes relatively abundant. The phenotypic hybrid zone between mimetic and nonmimetic admiral butterflies, comprising the polytypic Limenitis arthemis species complex, offers an ideal opportunity to test these predictions because the position of the hybrid zone is hypothesized to be controlled by the geographic range of Battus philenor , the chemically defended model. We used 29 years of observational field data from a continental-scale butterfly monitoring program, the 4th of July Butterfly Counts, to show that (1) the advantage of mimicry does not extend beyond the range of the model, (2) in contrast to expectations, the mimicry complex is maintained even where the model is rare and (3) the sharp phenotypic transition between mimetic and nonmimetic admiral populations occurs over a very narrow spatial scale corresponding to the limit of the model's range. These results suggest that, even at very low densities, there is selection for Batesian mimicry and it maintains the geographic position of this hybrid zone. Our findings highlight the value of large-scale, long-term citizen science monitoring programs for answering basic ecological and evolutionary questions. 相似文献
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Deregulated oncogenes such as MYC and RAS are typically insufficient to transform cells on their own due to the activation of pathways that restrain proliferation. Previous studies have shown that oncogenic H-Ras can induce proliferative arrest or senescence, depending on the cellular context. Here, we show that deregulated H-Ras activity can also lead to caspase-independent cell death with features of autophagy. Ras-induced autophagy was associated with upregulation of the BH3-only protein Noxa as well as the autophagy regulator Beclin-1. Silencing of Noxa or Beclin-1 expression reduced Ras-induced autophagy and increased clonogenic survival. Ras-induced cell death was also inhibited by coexpression of Bcl-2 family members that inhibit Beclin-1 function. Ras-induced autophagy was associated with Noxa-mediated displacement of the Bcl-2 family member, Mcl-1, from Beclin-1. Thus, Ras-induced expression of Noxa and Beclin-1 promotes autophagic cell death, which represents a mechanism to limit the oncogenic potential of deregulated Ras signals. 相似文献
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Dillingham MS 《Current biology : CB》2006,16(19):R844-R847
The first crystal structure of a ring helicase encircling single-stranded DNA reveals a mechanism for ATP-dependent DNA translocation. 相似文献
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Taylor D. Krueger Longteng Tang Cheng Chen Liangdong Zhu Isabella L. Breen Rebekka M. Wachter Chong Fang 《Protein science : a publication of the Protein Society》2023,32(1):e4517
Green-to-red photoconvertible fluorescent proteins (FPs) are vital biomimetic tools for powerful techniques such as super-resolution imaging. A unique Kaede-type FP named the least evolved ancestor (LEA) enables delineation of the evolutionary step to acquire photoconversion capability from the ancestral green fluorescent protein (GFP). A key residue, Ala69, was identified through several steady-state and time-resolved spectroscopic techniques that allows LEA to effectively photoswitch and enhance the green-to-red photoconversion. However, the inner workings of this functional protein have remained elusive due to practical challenges of capturing the photoexcited chromophore motions in real time. Here, we implemented femtosecond stimulated Raman spectroscopy and transient absorption on LEA-A69T, aided by relevant crystal structures and control FPs, revealing that Thr69 promotes a stronger π–π stacking interaction between the chromophore phenolate (P-)ring and His193 in FP mutants that cannot photoconvert or photoswitch. Characteristic time constants of ~60–67 ps are attributed to P-ring twist as the onset for photoswitching in LEA (major) and LEA-A69T (minor) with photoconversion capability, different from ~16/29 ps in correlation with the Gln62/His62 side-chain twist in ALL-GFP/ALL-Q62H, indicative of the light-induced conformational relaxation preferences in various local environments. A minor subpopulation of LEA-A69T capable of positive photoswitching was revealed by time-resolved electronic spectroscopies with targeted light irradiation wavelengths. The unveiled chromophore structure and dynamics inside engineered FPs in an aqueous buffer solution can be generalized to improve other green-to-red photoconvertible FPs from the bottom up for deeper biophysics with molecular biology insights and powerful bioimaging advances. 相似文献
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Sansom MS 《Current biology : CB》2000,10(5):R206-R209
The fourth transmembrane helix (S4) is the primary voltage-sensor of voltage-gated ion channels. Recent studies have used fluorescence resonance energy transfer as a spectroscopic ruler to determine the nature and magnitude of the voltage-induced movement of S4 that leads to channel opening. 相似文献
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Xiaming Pang Jingjing Zhang Hernando Lopez Yushu Wang Wenyang Li Katelyn L. O'Neill Jacquelynn J. D. Evans Nicholas M. George Jianhong Long Yi Chen Xu Luo 《The Journal of biological chemistry》2014,289(25):17802-17811
The BH3-only protein Noxa is a critical mediator of apoptosis and functions primarily by sequestering/inactivating the antiapoptotic Bcl-2 family protein Mcl-1. Although Noxa is a highly labile protein, recent studies suggested that it is degraded by the proteasome in a ubiquitylation-independent manner. In the present study, we investigated the mechanism of Noxa degradation and its ability to regulate the stability of Mcl-1. We found that the ubiquitylation-independent degradation of Noxa does not require a physical association with Mcl-1. A short stretch of amino acid residues in the C-terminal tail was found to mediate the proteasome-dependent degradation of Noxa. Ectopic placement of this degron was able to render other proteins unstable. Surprisingly, mutation of this sequence not only attenuated the rapid degradation of Noxa, but also stabilized endogenous Mcl-1 through the BH3-mediated direct interaction. Together, these results suggest that the C-terminal tail of Noxa regulates the stability of both Noxa and Mcl-1. 相似文献
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Hay RT 《Trends in cell biology》2007,17(8):370-376
The small ubiquitin-like modifier (SUMO) is involved in many cellular processes and is required for normal growth and development in all eukaryotes. Whereas lower eukaryotes have a single version of SUMO, higher eukaryotes have three versions: SUMO-1, -2 and -3. Similarly to most other ubiquitin-like proteins, the primary translation products of the SUMO genes need to be proteolytically processed to expose the C-terminal glycine that will be linked to lysine side chains in substrates. Processing of SUMO precursors is mediated by SUMO-specific proteases that also remove SUMO from modified proteins and depolymerise poly-SUMO chains. 相似文献
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Pheromones are detected by the vomeronasal organ using members of two receptor superfamilies: the V1Rs and V2Rs. New studies show that MHC class I molecules are co-expressed in particular combinations with specific V2Rs in the vomeronasal organ. The role of these MHC molecules is unknown, but they may be of considerable biological significance. 相似文献
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Evolution of primate theta-defensins: a serpentine path to a sweet tooth 总被引:11,自引:0,他引:11