A novel pH2 control on the expression of flagella in the hyperthermophilic strictly hydrogenotrophic methanarchaeaon Methanococcus jannaschii
A novel pH2 control on the expression of flagella in the hyperthermophilic strictly hydrogenotrophic methanarchaeaon Methanococcus jannaschii
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DOI：
10.1073/pnas.97.21.11522
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发表时间：
2000-10-10
影响因子：
11.1
通讯作者：
Wolfe, RS
中科院分区：
文献类型：
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作者：
Mukhopadhyay, B;Johnson, EF;Wolfe, RS
甲烷考古。詹纳斯基甲烷球菌，一种嗜热、自养的细菌。在两个氢分压(pH(2))的反应器中进行培养。178kPa(高)和650pA(超低)，对细胞进行比较蛋白质组分析。从这些研究中发现，当pH(2)高，细胞密度低(代表氢气过剩的组合)时，细胞中四种鞭毛相关多肽(FlaB2、FlaB3、Flad和FlaE)的水平非常低或检测不到；电子显微镜检查显示，大多数细胞没有鞭毛。无论是在高pH(2)的高细胞密度下，还是在低pH(2)的低细胞密度下，当氢变得有限时，鞭毛的合成都发生了。PH(2)变化实验的结果证实了上述观察结果。两种产甲烷酶(MTD和HMDX)的水平随pH(2)的变化与预期一致，因此它们作为内部对照。据我们所知，这是第一个在任何生命领域中通过氢来调节鞭毛表达的例子，也是第一次控制古生菌中鞭毛的合成。我们的工作还为以下每一种提供了唯一已知的例子：(I)在超低的、接近生态相关的p(H2)上纯培养产甲烷菌；(Ii)实验功能基因组学；以及(Iii)与詹纳什分枝杆菌的蛋白质组学的使用。
The methanarchaeon. Methanococcus jannaschii, a hyperthermophilic, autotrophic. and strictly hydrogenotrophic inhabitant of submarine hydrothermal vents, was cultivated in a reactor at two hydrogen partial pressure (pH(2)) values. 178 kPa (high) and 650 Pa (ultralow), and the cells were subjected to a comparative proteome analysis. From these studies, it was discovered that, when pH(2) was high and the cell density was low (a combination representing a hydrogen-excess condition), the cells possessed very low or undetectable levels of four flagella-related polypeptides (FlaB2, FlaB3, FlaD, and FlaE); electron microscopic examination showed that most of these cells were devoid of flagella. Flagella synthesis occurred when hydrogen became limiting either at high cell density under high pH(2) or at low cell density under low PH2. The results from a pH(2)-shift experiment corroborated the above observations. The pH(2)-dependent changes in the levels of two methanogenic enzymes (MTD and HMDX) were as expected, and thus they served as internal controls. To our knowledge, this is the first example for the regulation of expression of flagella by hydrogen in any domain of life and for a control of any kind on flagella synthesis in the archaea. Our work also provides the only known example for each of the following: (i) the pure culture cultivation of a methanogen at an ultralow, near ecologically relevant p(H2); (ii) experimental functional genomics for M. jannaschii; and (iii) the use of proteomics with M, jannaschii.