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101.
Rath P Demange P Saurel O Tropis M Daffé M Dötsch V Ghazi A Bernhard F Milon A 《The Journal of biological chemistry》2011,286(37):32525-32532
PorA and PorH are two small membrane proteins from the outer membrane of Corynebacterium glutamicum, which have been shown to form heteromeric ion channels and to be post-translationally modified by mycolic acids. Any structural details of the channel could not be analyzed so far due to tremendous difficulties in the production of sufficient amounts of protein samples. Cell-free (CF) expression is a new and remarkably successful strategy for the production of membrane proteins for which toxicity, membrane targeting, and degradation are key issues. In addition, reaction conditions can easily be modified to modulate the quality of synthesized protein samples. We developed an efficient CF expression strategy to produce the channel subunits devoid of post-translational modifications. (15)N-labeled PorA and PorH samples were furthermore characterized by NMR and gave well resolved spectra, opening the way for structural studies. The comparison of ion channel activities of CF-expressed proteins with channels isolated from C. glutamicum gave clear insights on the influence of the mycolic acid modification of the two subunits on their functional properties. 相似文献
102.
Monika W. Murcha Yan Wang Reena Narsai James Whelan 《Biochimica et Biophysica Acta (BBA)/General Subjects》2014
Background
Mitochondria play essential roles in the life and death of almost all eukaryotic cells, ranging from single-celled to multi-cellular organisms that display tissue and developmental differentiation. As mitochondria only arose once in evolution, much can be learned from studying single celled model systems such as yeast and applying this knowledge to other organisms. However, two billion years of evolution have also resulted in substantial divergence in mitochondrial function between eukaryotic organisms.Scope of Review
Here we review our current understanding of the mechanisms of mitochondrial protein import between plants and yeast (Saccharomyces cerevisiae) and identify a high level of conservation for the essential subunits of plant mitochondrial import apparatus. Furthermore, we investigate examples whereby divergence and acquisition of functions have arisen and highlight the emerging examples of interactions between the import apparatus and components of the respiratory chain.Major conclusions
After more than three decades of research into the components and mechanisms of mitochondrial protein import of plants and yeast, the differences between these systems are examined. Specifically, expansions of the small gene families that encode the mitochondrial protein import apparatus in plants are detailed, and their essential role in seed viability is revealed.General significance
These findings point to the essential role of the inner mitochondrial protein translocases in Arabidopsis, establishing their necessity for seed viability and the crucial role of mitochondrial biogenesis during germination. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research. 相似文献103.
太空环境改变生物工程细胞CHO(dhfr- 总被引:1,自引:0,他引:1
目的 :了解太空诱变对生物工程细胞CHO(dhfr---- 相似文献
104.
105.
溶藻弧菌铁载体合成及外膜蛋白表达的研究 总被引:3,自引:0,他引:3
初步研究了海洋动物病原菌溶藻弧菌的铁摄取机制。溶藻弧菌能够在高浓度铁螯合剂2-2二联吡啶的培养基中存活。在限铁环境中,溶藻弧菌生长受到抑制,补加铁可以消除这种抑制作用。通过铁载体定量检测,发现分离于发病鱼体的溶藻弧菌MVP01产铁载体量大于分离于海水的菌株No·1·1587。互补实验证明溶藻弧菌的铁载体粗提物能够被铁载体合成缺陷的大肠杆菌突变株AN93利用。在铁限制培养环境中,溶藻弧菌合成了约80kD铁调控外膜蛋白。铁摄取系统在溶藻弧菌的生存和致病性方面,都有重要的作用。 相似文献
106.
目的 构建L3 2_pGEX_5x_2重组质粒 ,诱导表达重组钩端螺旋体外膜脂蛋白LipL3 2。方法 PCR获取编码LipL3 2的基因片段 ,构建重组克隆载体和表达载体 ,转化受体菌 ,诱导表达重组LipL3 2蛋白。将重组LipL3 2蛋白和钩体抗血清进行Western_blot。结果 扩增出约 750bp的LipL3 2成熟蛋白基因 ,LipL3 2基因插入pGEX_5x_2表达载体 ,表达产物谷胱甘肽S_转移酶 (GST ,2 6× 10 3)与LipL3 2蛋白的融合蛋白的相对分子质量约为 53× 10 3 ,与预期大小一致。Western_blot显示重组LipL3 2蛋白能与钩体抗血清特异结合。结论 LipL3 2蛋白能在大肠埃希菌中表达 ,重组LipL3 2蛋白具有免疫反应性 相似文献
107.
细菌内依赖TonB的外膜铁转运体的研究进展 总被引:1,自引:0,他引:1
铁是细菌所必需的微量营养元素,但由于易被氧化溶解性低,生物体的利用率大大降低。细菌在进化过程中形成多种策略来吸收环境中低浓度的铁,不同类型铁的吸收通过外膜上依赖TonB的转运体(TonB-dependent transporters,TBDTs)完成,TBDTs结合不同形式的铁复合物,通过内膜上的TonB-ExbB-ExbD复合物提供能量完成转运,对其机制的研究一直是微生物基础生命活动研究中的热点问题。近年来新鉴定了一些TBDTs的结构,并对其功能和转运机制有了更深入的研究,对此进行了综述,不仅有助于进一步揭示细菌的铁转运机制,而且有助于寻找新的靶位点以开发新的治疗药物。 相似文献
108.
Outer membrane proteins of pathogenic spirochetes 总被引:10,自引:0,他引:10
109.
To study the mechanism of action of diflubenzuron (DFB) and other benzoylphenylureas, we have initially hypothesized that their action may be related to exocytosis: to test the hypothesis, we obtained an intracellular vesicle preparation from the homogenate of integument of newly molted American cockroachs (Periplaneta americana L.) in 10 mM MES buffer containing 250 mM sucrose (isotonic) and 2.5 mM MgSO4, at pH 6.6. By studying DFB's effect on various ion transporting activities, we demonstrated that calcium uptake in this intracellular particulate preparation was significantly inhibited by DFB at low concentrations (e.g., 10−8 M). Such an inhibitory effect of DFB on Ca2+ uptake was eliminated by the addition of ionophores or membrane disruptors, as well as the sonication of vesicle preparation. On the other hand, oligomycin, protein phosphorylation modulators, Na+, and Li+ did not affect the calcium uptake. Among ionophores, agents disrupting H+ gradients (e.g. FCCP and NEM) totally eliminated 45Ca uptaking activity by vesicles as well as the inhibitory effect of DFB. Among calcium ion modulators, calmodulin inhibitors such as calmidazolium and trifluoperazine decreased the Ca2+-uptake, whereas membrane calcium channel blocker, verapamil, did not. ATP and γ-S-GTP stimulated Ca2+ uptake. However, the former increased only the DFB insensitive portion and the latter largely the DFB sensitive part of Ca2+. Together these data support the hypothesis that the action site of DFB in this preparation is the GTP-dependent Ca2+ transport process which is coupled to vacuolar type intracellular vesicles in the integument cells. 相似文献
110.
R. Cevenini M. Donati V. Sambri F. Rumpianesi M. La Placa 《FEMS microbiology letters》1987,42(1):47-51
The reactivity of the major outer membrane protein (MOMP) of Chlamydia trachomatis (LGV2 serotype) with 15 monoclonal antibodies was studied during the course of developmental cycle by immunoblotting and immunofluorescence. The monoclonal antibodies reacted in immunoblots with the MOMP of both elementary bodies (EBs) and reticulate bodies (RBs). Using an immunofluorescence test with LGV2-infected cell cultures, the 15 monoclonal antibodies could be divided into 5 groups, according to the time of appearance of their reactivity with the cell culture. 相似文献