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Dafang Wang Chuanhe Yu Tao Zuo Jianbo Zhang David F. Weber Thomas Peterson 《Genetics》2015,201(3):925-935
The maize Ac/Ds transposon family was the first transposable element system identified and characterized by Barbara McClintock. Ac/Ds transposons belong to the hAT family of class II DNA transposons. We and others have shown that Ac/Ds elements can undergo a process of alternative transposition in which the Ac/Ds transposase acts on the termini of two separate, nearby transposons. Because these termini are present in different elements, alternative transposition can generate a variety of genome alterations such as inversions, duplications, deletions, and translocations. Moreover, Ac/Ds elements transpose preferentially into genic regions, suggesting that structural changes arising from alternative transposition may potentially generate chimeric genes at the rearrangement breakpoints. Here we identified and characterized 11 independent cases of gene fusion induced by Ac alternative transposition. In each case, a functional chimeric gene was created by fusion of two linked, paralogous genes; moreover, each event was associated with duplication of the ∼70-kb segment located between the two paralogs. An extant gene in the maize B73 genome that contains an internal duplication apparently generated by an alternative transposition event was also identified. Our study demonstrates that alternative transposition-induced duplications may be a source for spontaneous creation of diverse genome structures and novel genes in maize. 相似文献
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用基因组重排技术选育赖氨酸高产菌株 总被引:6,自引:1,他引:5
摘要:【目的】以北京棒杆菌(Corynebacterium pekinense)1为研究对象,选育赖氨酸高产菌株,并探索赖氨酸产生菌基因组重排育种的基本规律。【方法】利用基因组重排技术选育赖氨酸高产菌株。【结果】通过四轮基因组重排成功选育出了5株遗传稳定的高产赖氨酸菌株,其中1株重排菌株赖氨酸产量达到16.95 g/dL,比原始菌株Corynebacterium pekinense 1赖氨酸产量提高了37.14%,比亲本菌株赖氨酸产量提高了17.46%~31.19%。【结论】首次采用基因组重排技术改良赖氨酸产生菌,成功选育出了5株产量较稳定的高产赖氨酸菌株,具有潜在的应用价值。 相似文献
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耐温性L-谷氨酸发酵菌种的选育 总被引:1,自引:0,他引:1
应用基因组改组技术提高,L-谷氨酸生产菌在高温发酵条件下的谷氨酸产量。以天津短杆菌T6—13变异株SW07-1为原始亲株,分别经紫外线(UV)-硫酸二乙酯(DES)和X射线诱变,获得5株耐温性能略有提高的突变菌株。经2轮基因组改组,获得耐高温(能在44℃生长)的L-谷氨酸菌株F2-50。F2—50在38℃下,摇瓶发酵40h,发酵液中L-谷氨酸浓度比原始出发菌株提高了近41%,在41℃高温下,摇瓶发酵40h,L-谷氨酸浓度比原始出发菌株提高了近2倍。 相似文献
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M. Abou Hachem S. Bozonnet M. Willemoë s B. Kramh ft K. Fukuda B. C. B nsager M. T. Jensen J. N hr S. Tranier N. Juge X. Robert R. Haser N. Aghajari B. Svensson 《Biocatalysis and Biotransformation》2006,24(1):83-93
-Amylases are endo-acting retaining enzymes of glycoside hydrolase family 13 with a catalytic (β/)8-domain containing an inserted loop referred to as domain B and a C-terminal anti-parallel β-sheet termed domain C. New insights integrate the roles of Ca2 + , different substrates, and proteinaceous inhibitors for -amylases. Isozyme specific effects of Ca2 + on the 80% sequence identical barley -amylases AMY1 and AMY2 are not obvious from the two crystal structures, containing three superimposable Ca2 + with identical ligands. A fully hydrated fourth Ca2 + at the interface of the AMY2/barley -amylase/subtilisin inhibitor (BASI) complex interacts with catalytic groups in AMY2, and Ca2 + occupies an identical position in AMY1 with thiomaltotetraose bound at two surface sites. EDTA-treatment, DSC, and activity assays indicate that AMY1 has the highest affinity for Ca2 + . Subsite mapping has revealed that AMY1 has ten functional subsites which can be modified by means protein engineering to modulate the substrate specificity. Other mutational analyses show that surface carbohydrate binding sites are critical for interaction with polysaccharides. The conserved Tyr380 in the newly discovered 'sugar tongs' site in domain C of AMY1 is thus critical for binding to starch granules. Furthermore, mutations of binding sites mostly reduced the degree of multiple attack in amylose hydrolysis. AMY1 has higher substrate affinity than AMY2, but isozyme chimeras with AMY2 domain C and other regions from AMY1 have higher substrate affinity than both parent isozymes. The latest revelations addressing various structural and functional aspects that govern the mode of action of barley -amylases are reported in this review. 相似文献
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We describe a new approach to in vitro DNA recombination termed the Separate-Mixing method in this study. The reaction process
of this method consists of two stages: at the first stage the reaction was implemented in two parallel teams, which generated
random recombination by template-switching of growing poly-nucleotides from primers in the presence of unidirectional single-stranded
DNA fragments used as templates, and then both teams were mixed together for further extension and recombination of DNA sequences
at the second stage. Due to this particular strategy, the reaction process was also accompanied by two other processes of
DNA shuffling and StEP simultaneously. Two AdoMet synthetase genes, sam2 from Saccharomyces cerevisiae and metK from Escherichia coli, which have only 56% homology on the DNA level, were used for recombination with the Separate-Mixing method. DNA recombination
was available after a single round of reaction. When 10 randomly selected recombinants were sequenced, an unshuffled parental
clone was not found, nor was unexpected insertion, deletion, or rearrangement detected. An evolved gene, sam’, was obtained after screening and selection, which could obviously increase the accumulation of AdoMet in S. cerevisiae.
Published in Russian in Molekulyarnaya Biologiya, 2006, Vol. 40, No. 3, pp. 546–553.
This article was submitted by the authors in English. 相似文献
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剪接后的内含子与相应mRNA序列的相互作用在基因表达调控过程中起着非常重要的作用。基于27个物种的核糖核蛋白基因序列,采用Smith—Waterman局域比对方法得到外显子连接序列与相应内含子序列的最佳匹配片段,分析了外显子连接序列上的匹配频率分布和匹配片段的序列特征。发现一些低等真核生物EJC结合区域的匹配频率明显低于其它区域,所有物种EJC结合区域的序列构成呈现出相对低的结构序。最佳匹配片段的平均长度和配对率分布与siRNA和miRNA的结合特征相同。推测EJC和内含子在与外显子序列结合的过程中存在相互竞争和相互协作的关系,内含子中部序列在基因表达调控过程中起着重要的作用。 相似文献