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茎瘤固氮根瘤菌甲基化受体蛋白Tlp1的功能
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国家自然科学基金项目(No. 31370108,31570063);中国科学院重点部署项目(No. KZZD-EW-14);山东省自主创新及成果转化专项项目(No. 2014ZZCX07303);中国科学院百人计划项目;烟台市科技发展计划项目(No. 2013JH021)


Function of a methyl-accepting chemotaxis protein Tlp1 in Azorhizobium caulinodans ORS571
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    摘要:

    【目的】考察茎瘤固氮根瘤菌中趋化基因簇上游的受体蛋白Tlp1编码基因的突变表型,初步探究其功能机理。【方法】利用同源重组和三亲本接合转移的方法构建突变株,在TY培养基中测定生长情况,半固体平板法观察趋化圈,刚果红固体培养基观察胞外多糖和次生代谢产物的分泌,乙炔还原法测定菌株的固氮酶活性。【结果】与野生型菌株相比,tlp1突变株的生长速率没有影响。在以甘油为碳源的L3半固体平板上突变株的趋化圈变小,其回补菌株能部分回补趋化能力。突变株的胞外多糖分泌与野生型没有区别,但其次生代谢产物黑色素出现的时间比野生型稍早。在固氮酶活性测定中,发现突变株酶活性明显比野生型降低,回补菌株能够部分回补。【结论】茎瘤固氮根瘤菌Tlp1蛋白对甘油表现出一定的趋化能力,并且影响细菌的次生代谢产物和固氮能力。

    Abstract:

    [Objective] To study the mutation phenotype of the methyl-accepting chemotaxis protein Tlp1 (transducer-like protein) located in the upstream of the gene cluster of Azorhizobium caulinodans ORS571, and to explore its functional mechanism. [Methods] The tlp1 mutant strain was constructed by the homologous recombination and triparental conjugation. Growth of the wild-type strain ORS571 and the tlp1 mutant was compared by measuring OD600 over time of cultures in TY medium. The semi-solid plate assay was used to test the ability of chemotaxis. The production of extracellular polysaccharide and secondary metabolites was measured through Congo red solid culture medium. The acetylene reduction assay was used to measure nitrogen fixation ability. [Results] Compared with the wild type, the growth of the mutant in rich media was the same as that of the wild type. The tlp1 mutant was impaired in chemotaxis to glycerol, and the complemented strain’s chemotactic capability could be partially complemented. The production of extracellular polysaccharides secreted from tlp1 mutant and wild type has no difference, but one of the secondary metabolites — the melanin tlp1 mutant appeared earlier than the wild type. The nitrogenase activity of tlp1 mutant strain was weaker than that of the wild type, and the complemented strain could complement part of the nitrogen fixation ability. [Conclusion] The methyl-accepting chemotaxis protein Tlp1 of A. caulinodans ORS571 showed a certain ability of chemotaxis to glycerol, and also affected the secondary metabolites and the nitrogenase activity in ORS571.

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杨金保,刘卫,姜南,吴海龙,李岩,李润植,张红梅,解志红. 茎瘤固氮根瘤菌甲基化受体蛋白Tlp1的功能[J]. 微生物学通报, 2017, 44(3): 648-654

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  • 在线发布日期: 2017-03-09
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