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81.
Iwaki M Yakovlev G Hirst J Osyczka A Dutton PL Marshall D Rich PR 《Biochemistry》2005,44(11):4230-4237
The redox-linked protonation chemistry of the iron-sulfur protein (ISP) of the cytochrome bc(1) complex was studied by analysis of the pH dependencies of redox difference spectra using perfusion/electrochemically induced attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. The ISP of Rhodobacter capsulatus within the intact cytochrome bc(1) complex was analyzed in a mutant form in which the midpoint potential of cytochrome c(1) was lower than that of the ISP. This was compared to a soluble domain of the ISP from the bovine bc(1) complex. Spectra of in situ bacterial and isolated bovine proteins differ markedly only in part of their amide I regions with the in situ protein having additional pH-dependent component(s). Apart from this, both in situ and isolated proteins exhibited the same pH-dependent IR features in reduced minus oxidized difference spectra. Specifically, at high pH, a strong H/D insensitive negative band appeared at 1447/1450 cm(-)(1), together with a peak at 1310 cm(-)(1), the change of a 1267/1255 cm(-)(1) peak/trough into a simple 1266 cm(-)(1) peak, and a trough at 1107 cm(-)(1). Comparison with spectra of model materials indicates that all four signals arise from an imidazolate to imidazole transition of histidine, hence providing the first direct demonstration that histidine is the redox-linked protonation site of the ISP. The 1450 cm(-)(1) band can be assigned to a ring stretch that is unique to the imidazolate form of histidine. It is relatively sharp, has a high extinction coefficient, and provides a novel marker band for the detection of imidazolate intermediates in enzymatic mechanisms generally. 相似文献
82.
Fanconi anemia protein FANCD2 promotes immunoglobulin gene conversion and DNA repair through a mechanism related to homologous recombination 下载免费PDF全文
Yamamoto K Hirano S Ishiai M Morishima K Kitao H Namikoshi K Kimura M Matsushita N Arakawa H Buerstedde JM Komatsu K Thompson LH Takata M 《Molecular and cellular biology》2005,25(1):34-43
Recent studies show overlap between Fanconi anemia (FA) proteins and those involved in DNA repair mediated by homologous recombination (HR). However, the mechanism by which FA proteins affect HR is unclear. FA proteins (FancA/C/E/F/G/L) form a multiprotein complex, which is responsible for DNA damage-induced FancD2 monoubiquitination, a key event for cellular resistance to DNA damage. Here, we show that FANCD2-disrupted DT40 chicken B-cell line is defective in HR-mediated DNA double-strand break (DSB) repair, as well as gene conversion at the immunoglobulin light-chain locus, an event also mediated by HR. Gene conversions occurring in mutant cells were associated with decreased nontemplated mutations. In contrast to these defects, we also found increased spontaneous sister chromatid exchange (SCE) and intact Rad51 foci formation after DNA damage. Thus, we propose that FancD2 promotes a subpathway of HR that normally mediates gene conversion by a mechanism that avoids crossing over and hence SCEs. 相似文献
83.
In mitochondria, oxidative phosphorylation and enzymatic oxidation of biogenic amines by monoamine oxidase produce reactive
oxygen and nitrogen species, which are proposed to cause neuronal cell death in neurodegenerative disorders, including Parkinson’s
and Alzheimer’s disease. In these disorders, mitochondrial dysfunction, increased oxidative stress, and accumulation of oxidation-modified
proteins are involved in cell death in definite neurons. The interactions among these factors were studied by use of a peroxynitrite-generating
agent, N-morpholino sydnonimine (SIN-1) and an inhibitor of complex I, rotenone, in human dopaminergic SH-SY5Y cells. In control cells,
peroxynitrite nitrated proteins, especially the subunits of mitochondrial complex I, as 3-nitrotyrosine, suggesting that neurons
are exposed to constant oxidative stress even under physiological conditions. SIN-1 and an inhibitor of proteasome, carbobenzoxy-l-isoleucyl-γ-t-butyl-l-analyl-l-leucinal (PSI), increased markedly the levels of nitrated proteins with concomitant induction of apoptosis in the cells.
Rotenone induced mitochondrial dysfunction and accumulation and aggregation of proteins modified with acrolein, an aldehyde
product of lipid peroxidation in the cells. At the same time, the activity of the 20S β-subunit of proteasome was reduced
significantly, which degrades oxidative-modified protein. The mechanism was proved to be the result of the modification of
the 20S β-subunit with acrolein and to the binding of other acrolein-modified proteins to the 20S β-subunit.
Increased oxidative stress caused by SIN-1 treatment induced a decline in the mitochondrial membrane potential, ΔΨm, and activated
mitochondrial apoptotic signaling and induced cell death in SH-SY5Y cells. As another pathway, p38 mitogen-activated protein
(MAP) kinase and exracellular signal-regulated kinase (ERK) mediated apoptosis induced by SIN-1. On the other hand, a series
of neuroprotective propargylamine derivatives, including rasagiline [N-propargyl-1(R)aminoindan]and (−)deprenyl, intervened in the activation of apoptotic cascade by reactive oxygen species-reactive nitrogen
species in mitochondria through stabilization of the membrane potential, ΔΨm. In addition, rasagiline induced antiapoptotic
Bcl-2 and glial cell line-derived neurotrophic factor (GDNF) in SH-SY5Y cells, which was mediated by the ERK-nuclear factor
(NF)-κB pathway. These results are discussed in relation to the interaction of oxidative stress and mitochondria in the regulation
of neuronal death and survival in neurodegenerative diseases. 相似文献
84.
85.
Music and dance are two remarkable human characteristics that are closely related. Communication through integrated vocal and motional signals is also common in the courtship displays of birds. The contribution of songbird studies to our understanding of vocal learning has already shed some light on the cognitive underpinnings of musical ability. Moreover, recent pioneering research has begun to show how animals can synchronize their behaviors with external stimuli, like metronome beats. However, few studies have applied such perspectives to unraveling how animals can integrate multimodal communicative signals that have natural functions. Additionally, studies have rarely asked how well these behaviors are learned. With this in mind, here we cast a spotlight on an unusual animal behavior: non-vocal sound production associated with singing in the Java sparrow (Lonchura oryzivora), a songbird. We show that male Java sparrows coordinate their bill-click sounds with the syntax of their song-note sequences, similar to percussionists. Analysis showed that they produced clicks frequently toward the beginning of songs and before/after specific song notes. We also show that bill-clicking patterns are similar between social fathers and their sons, suggesting that these behaviors might be learned from models or linked to learning-based vocalizations. Individuals untutored by conspecifics also exhibited stereotypical bill-clicking patterns in relation to song-note sequence, indicating that while the production of bill clicking itself is intrinsic, its syncopation appears to develop with songs. This paints an intriguing picture in which non-vocal sounds are integrated with vocal courtship signals in a songbird, a model that we expect will contribute to the further understanding of multimodal communication. 相似文献
86.
Okita K Matsumura Y Sato Y Okada A Morizane A Okamoto S Hong H Nakagawa M Tanabe K Tezuka K Shibata T Kunisada T Takahashi M Takahashi J Saji H Yamanaka S 《Nature methods》2011,8(5):409-412
We report a simple method, using p53 suppression and nontransforming L-Myc, to generate human induced pluripotent stem cells (iPSCs) with episomal plasmid vectors. We generated human iPSCs from multiple donors, including two putative human leukocyte antigen (HLA)-homozygous donors who match ~20% of the Japanese population at major HLA loci; most iPSCs are integrated transgene-free. This method may provide iPSCs suitable for autologous and allologous stem-cell therapy in the future. 相似文献
87.
Jin ZB Okamoto S Osakada F Homma K Assawachananont J Hirami Y Iwata T Takahashi M 《PloS one》2011,6(2):e17084
Retinitis pigmentosa (RP) is the most common inherited human eye disease resulting in night blindness and visual defects. It is well known that the disease is caused by rod photoreceptor degeneration; however, it remains incurable, due to the unavailability of disease-specific human photoreceptor cells for use in mechanistic studies and drug screening. We obtained fibroblast cells from five RP patients with distinct mutations in the RP1, RP9, PRPH2 or RHO gene, and generated patient-specific induced pluripotent stem (iPS) cells by ectopic expression of four key reprogramming factors. We differentiated the iPS cells into rod photoreceptor cells, which had been lost in the patients, and found that they exhibited suitable immunocytochemical features and electrophysiological properties. Interestingly, the number of the patient-derived rod cells with distinct mutations decreased in vitro; cells derived from patients with a specific mutation expressed markers for oxidation or endoplasmic reticulum stress, and exhibited different responses to vitamin E than had been observed in clinical trials. Overall, patient-derived rod cells recapitulated the disease phenotype and expressed markers of cellular stresses. Our results demonstrate that the use of patient-derived iPS cells will help to elucidate the pathogenic mechanisms caused by genetic mutations in RP. 相似文献
88.
Masayo Tomita Ayami Kikuchi Mariko Kobayashi Masashi Yamaguchi Shinsuke Ifuku Shiro Yamashoji Akikazu Ando Akihiro Saito 《Antonie van Leeuwenhoek》2013,104(5):737-748
We characterized the antifungal activity of the Bacillus circulans subclass III MH-K1 chitosanase (MH-K1 chitosanase), which is one of the most intensively studied glycoside hydrolases (GHs) that belong to GH family 46. MH-K1 chitosanase inhibited the growth of zygomycetes fungi, Rhizopus and Mucor, even at 10 pmol (0.3 μg)/ml culture probably via its fungistatic effect. The amino acid substitution E37Q abolished the antifungal activity of MH-K1 chitosanase, but retained binding to chitotriose. The E37Q mutant was fused with green fluorescent protein (GFP) at its N-terminus and proved to act as a chitosan probe in combination with wheat-germ agglutinin (WGA), which is a chitin-specific binding lectin. The GFP-fused MH-K1 chitosanase mutant E37Q (GFP-E37Q) bound clearly to the hyphae of the Rhizopus and Mucor strains, indicating the presence of chitosan. In contrast, Cy5-labelled WGA (Cy5-WGA), but not GFP-E37Q, stained the hyphae of non-zygomycetes species, i.e. Fusarium oxysporum, Penicillium expansum, and Aspergillus awamori. When the mycelia of Rhizopus oryzae were treated with wild type MH-K1 chitosanase, they could not bind to GFP-E37Q but were stained instead by Cy5-WGA. We conclude that chitin is covered by chitosan in the cell walls of R. oryzae. 相似文献
89.
90.
Masayo Sakaki-Yumoto Yoko KatsunoRik Derynck 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013