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991.
Nan Zhang Zhentai Han Guiling Sun Angela Hoffman Iain W. Wilson Yanfang Yang Qian Gao Jianqiang Wu Dan Xie Jungui Dai Deyou Qiu 《Biochemical and biophysical research communications》2014
Taxol is a well-known effective anticancer compound. Due to the inability to synthesize sufficient quantities of taxol to satisfy commercial demand, a biotechnological approach for a large-scale cell or cell-free system for its production is highly desirable. Several important genes in taxol biosynthesis are currently still unknown and have been shown to be difficult to isolate directly from Taxus, including the gene encoding taxoid 9α-hydroxylase. Ginkgo biloba suspension cells exhibit taxoid hydroxylation activity and provides an alternate means of identifying genes encoding enzymes with taxoid 9α-hydroxylation activity. Through analysis of high throughput RNA sequencing data from G. biloba, we identified two candidate genes with high similarity to Taxus CYP450s. Using in vitro cell-free protein synthesis assays and LC–MS analysis, we show that one candidate that belongs to the CYP716B, a subfamily whose biochemical functions have not been previously studied, possessed 9α-hydroxylation activity. This work will aid future identification of the taxoid 9α-hydroxylase gene from Taxus sp. 相似文献
992.
Negatively twisted DNA is essential to many biological functions. Due to torsional stress, duplex DNA can have local, sequence-dependent structural defects. In this work, a thermodynamic model of DNA was built to qualitatively predict the local sequence-dependent mechanical instabilities under torsional stress. The results were compared to both simulation of a coarse-grained model and experiment results. By using the Kirkwood superposition approximation, we built an analytical model to represent the free energy difference ΔW of a hydrogen-bonded basepair between the B-form helical state and the basepair opened (or locally melted) state, within a given sequence under torsional stress. We showed that ΔW can be well approximated by two-body interactions with its nearest-sequence-neighbor basepairs plus a free energy correction due to long-range correlations. This model is capable of rapidly predicting the position and thermodynamics of local defects in a given sequence. The result qualitatively matches with an in vitro experiment for a long DNA sequence (>4000 basepairs). The 12 parameters used in this model can be further quantitatively refined when more experimental data are available. 相似文献
993.
Robert?P. Johnson Aaron?M. Fleming Qian Jin Cynthia?J. Burrows Henry?S. White 《Biophysical journal》2014,107(4):924-931
The latch region of the wild-type protein pore α-hemolysin (α-HL) constitutes a sensing zone for individual abasic sites (and furan analogs) in double-stranded DNA (dsDNA). The presence of an abasic site or furan within a DNA duplex, electrophoretically captured in the α-HL vestibule and positioned at the latch region, can be detected based on the current blockage prior to duplex unzipping. We investigated variations in blockage current as a function of temperature (12–35°C) and KCl concentration (0.15–1.0 M) to understand the origin of the current signature and to optimize conditions for identifying the base modification. In 1 M KCl solution, substitution of a furan for a cytosine base in the latch region results in an ∼8 kJ mol−1 decrease in the activation energy for ion transport through the protein pore. This corresponds to a readily measured ∼2 pA increase in current at room temperature. Optimal resolution for detecting the presence of a furan in the latch region is achieved at lower KCl concentrations, where the noise in the measured blockage current is significantly lower. The noise associated with the blockage current also depends on the stability of the duplex (as measured from the melting temperature), where a greater noise in the measured blockage current is observed for less stable duplexes. 相似文献
994.
Characterization of a novel human CDK5 splicing variant that inhibits Wnt/β-catenin signaling 总被引:1,自引:0,他引:1
Qiang Li Xianghua Liu Mingjun Zhang Guangming Ye Qian Qiao Yichen Ling Yanhua Wu Yuanyuan Zhang Long Yu 《Molecular biology reports》2010,37(5):2415-2421
The cyclin-dependent kinases (CDKs) are a family of serine/threonine kinases, playing an essential role in regulating cell-cycle
progression. In our present work, human CDK5 and a novel CDK5 splicing variant, named as CDK5-SV, were cloned from the cDNA library of human testis. CDK5-SV lacking the exon 7 of CDK5 encodes a protein of 260 amino acids. Through RT-PCR analysis in different human tissues, CDK5-SV was found to be expressed in testis, skeletal muscle, colon, bone marrow and ovary, while CDK5 was ubiquitously expressed. Immunofluorescence experiment in HeLa cells showed that the subcellular localizations of CDK5-SV
and CDK5 were totally different. CDK5 mainly located in the cytoplasm, while CDK5-SV accumulated in nucleus. Reporter gene
assay showed that when co-transfected with β-catenin, CDK5 and CDK5-SV could both strongly inhibit the Wnt/β-catenin signaling pathway. Consistently, CDK5-SV could also interact with β-catenin
as CDK5 does. Taken together, our findings suggest that CDK5-SV might also be a negative regulator of Wnt/β-catenin signaling
pathway. 相似文献
995.
Guo-Liang Qian Jia-Qin Fan De-Feng Chen Yue-Jing Kang Bing Han Bai-Shi Hu Feng-Quan Liu 《Biological Control》2010,52(1):17-23
An N-acyl homoserine lactonase gene aiiA, transcribed by a strong and constitutive Escherichia coli promoter Plpp (Accession No. EU723847), was transformed into Lysobacter enzymogenes strain OH11, creating strain OH11A. The N-acyl-homoserine lactone (AHL)-degradation assay showed that transformant OH11A acquired the ability to degrade AHL molecules produced by Agrobacterium tumefaciens, Pectobacterium carotovorum, Pseudomonas syringae pv. tomato strain DC3000 and Acidovorax avenae subsp. citrulli. Pathogenicity tests showed that while the parental strain OH11 did not reduce P. carotovorum infection, the transformant OH11A caused a strong reduction of Pectobacterium virulence on Chinese cabbage and cactus, whereas strain OH11A did not seem to interfere with the normal growth of this pathogen in cabbages. In antimicrobial activity assays, strain OH11A and OH11 showed similar antimicrobial activity against Phytophthora capsici and Sclerotinia sclerotiorum. This work provided a new strategy for developing genetically engineered multi-functional L. enzymogenes strains that possessed the ability to biologically control fungal pathogens and reduce bacterial pathogenicity. 相似文献
996.
997.
Xiaojuan Sun Hui He Zhihui Xie Weiping Qian Haiyen E. Zhau Leland W. K. Chung Fray F. Marshall Ruoxiang Wang 《In vitro cellular & developmental biology. Animal》2010,46(6):538-546
Prostate stromal cells may play binary roles in the process of prostate cancer development. As the first to be encountered
by infiltrating prostate cancer cells, prostate stromal cells form the first defense line against prostate cancer progression
and metastasis. However, interaction between prostate cancer and stromal cells may facilitate the formation of a tumor microenvironment
favoring cancer cell growth and survival. To establish an experimental system for studying the interaction between cancer
and stromal cells, we isolated three matched pairs of normal and cancer-associated human prostate stromal clones. In this
report, we describe the morphologic and behavioral characteristics of these cells and their effect on LNCaP prostate cancer
cells in co-culture. Unlike LNCaP prostate cancer cells, the isolated prostate stromal clones are large fibroblast-like cells
with a slow proliferation rate. Growth and survival of these clones are not affected by androgens. The stromal cells display
high resistance to serum starvation, while cancer-associated stromal clones have differentiated survival ability. In co-culture
experiments, the stromal cells protected some LNCaP prostate cancer cells from death by serum starvation, and cancer-associated
stromal clones showed more protection. This work thus established a panel of valuable human prostate stromal cell lines, which
could be used in co-culture to study the interaction between prostate cancer and prostate stromal cells. 相似文献
998.
999.
Kato AS Gill MB Ho MT Yu H Tu Y Siuda ER Wang H Qian YW Nisenbaum ES Tomita S Bredt DS 《Neuron》2010,68(6):1082-1096
Transmembrane AMPA receptor regulatory proteins (TARPs) and cornichon proteins (CNIH-2/3) independently modulate AMPA receptor trafficking and gating. However, the potential for interactions of these subunits within an AMPA receptor complex is unknown. Here, we find that TARPs γ-4, γ-7, and γ-8, but not γ-2, γ-3, or γ-5, cause AMPA receptors to "resensitize" upon continued glutamate application. With γ-8, resensitization occurs with all GluA subunit combinations; however, γ-8-containing hippocampal neurons do not display resensitization. In recombinant systems, CNIH-2 abrogates γ-8-mediated resensitization and modifies AMPA receptor pharmacology and gating to match that of hippocampal neurons. In hippocampus, γ-8 and CNIH-2 associate in postsynaptic densities and CNIH-2 protein levels are markedly diminished in γ-8 knockout mice. Manipulating neuronal CNIH-2 levels modulates the electrophysiological properties of extrasynaptic and synaptic γ-8-containing AMPA receptors. Thus, γ-8 and CNIH-2 functionally interact with common hippocampal AMPA receptor complexes to modulate synergistically kinetics and pharmacology. 相似文献
1000.
Fang Du Li Zhu Zhong-Ming Qian Xiao-Mei Wu Wing-Ho Yung Ya Ke 《生物化学与生物物理学报:疾病的分子基础》2010,1802(11):1048-1053
It has been demonstrated that hypoxia-inducible factor-1 alpha (HIF-1 alpha) mediates ischemic tolerance induced by hypoxia/ischemia or pharmacological preconditioning. In addition, preconditioning stimuli can be cross-tolerant, safeguarding against other types of injury. We therefore hypothesized HIF-1 alpha might also be associated with ischemic tolerance induced by hyperthermic preconditioning. In the present study, we demonstrated for the first time that 6 h of hyperthermia (38 °C or 40 °C) could induce a characteristic “reactive” morphology and a significant increase in the expression of bystin in astrocytes. We also showed that pre-treatment with 6 h of hyperthermia resulted in a significant increase in cell viability and a remarkable decrease in lactate dehydrogenase (LDH) release and apoptosis development in the astrocytes that were exposed to 24 h of ischemia and a subsequent 24 h of reperfusion. Analysis of mechanisms showed that hyperthermia could lead to a significant increase in HIF-1 alpha expression and also the HIF-1 binding activity in the ischemia/reperfusion astrocytes. The data provide evidence to our hypothesis that the up-regulation of HIF-1 alpha is associated with the protective effects of hyperthermic preconditioning on astrocytes against ischemia/reperfusion injury. 相似文献