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首页> 外文期刊>Journal of bacteriology >Accumulation of a nod gene inducer, the flavonoid naringenin, in the cytoplasmic membrane of Rhizobium leguminosarum biovar viciae is caused by the pH-dependent hydrophobicity of naringenin.
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Accumulation of a nod gene inducer, the flavonoid naringenin, in the cytoplasmic membrane of Rhizobium leguminosarum biovar viciae is caused by the pH-dependent hydrophobicity of naringenin.

机译：Nod基因诱导剂类黄酮柚皮苷在豆科根瘤菌根瘤菌细胞质膜中的积累是由柚皮苷的pH依赖性疏水性引起的。

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摘要

Most Sym plasmid-localized nodulation genes of Rhizobium leguminosarum bv. viciae are only expressed upon activation of the NodD protein by plant flavonoids, e.g., naringenin (S. A. J. Zaat, C. A. Wijffelman, H. P. Spaink, A. A. N. van Brussel, and B. J. J. Lugtenberg, J. Bacteriol, 169:198-204, 1987). As part of a study on the mechanism of NodD protein activation, the mechanism of uptake and the intracellular fate of [3H]naringenin were studied. Naringenin was accumulated by Rhizobium cells without apparent metabolic conversion to an 80-fold-higher concentration in a process which did not require any of the other Sym plasmid-localized nod genes. Naringenin accumulation was nonsaturable, highly reversible, and not inhibited by the presence of other flavonoids or the metabolic inhibitors potassium cyanide, sodium azide, 2,4-dinitrophenol, and carbonyl cyanide m-chlorophenylhydrazone. These data indicate an accumulation mechanism without high affinity sites which does not use cellular energy. In vitro, naringenin has high affinity for the cytoplasmic membrane. This binding was pH dependent, very high at pH 5.7 and not present anymore at pH 9.7. A similar pH dependency was found for the affinity of naringenin for the olive oil fraction of a biphasic olive oil-water system. pH-dependent changes in the UV spectrum indicate ionization of naringenin at high pH to a negatively charged form. Since it has recently been shown that the nodD gene product is located in the cytoplasmic membrane (H. R. M. Schlaman, H. P. Spaink, R. J. H. Okker, and B. J. J. Lugtenberg, J. Bacteriol., in press), our data are consistent with a model in which the un-ionized form of naringenin accumulates in the cytoplasmic membrane and activates, in a metabolically unaltered form, the NodD protein.
机译：多数Sym质粒定位的豆科根瘤菌根瘤基因。蚕豆仅在植物黄酮类化合物（如柚皮素）激活NodD蛋白时才表达（S.A.J. Zaat，C.A.Wijffelman，H.P.Spanish，A.N.van Brussel和B.J.L.Lugtenberg，J.Bacteriol，169：198-204，1987）。作为NodD蛋白质激活机制研究的一部分，研究了[3H]柚皮素的摄取机制和细胞内命运。柚皮素是由根瘤菌细胞积累的，在不需要任何其他Sym质粒定位的nod基因的过程中，没有明显的代谢转化为高80倍的浓度。柚皮素的积累是不饱和的，高度可逆的，并且不受其他类黄酮或代谢抑制剂氰化钾，叠氮化钠，2,4-二硝基苯酚和羰基氰化物间氯苯hydr的存在的抑制。这些数据表明没有高亲和力位点的不使用细胞能量的积累机制。在体外，柚皮苷对细胞质膜具有高亲和力。这种结合是pH依赖性的，在pH 5.7时非常高，在pH 9.7时不再存在。发现柚皮素对双相橄榄油-水系统的橄榄油馏分的亲和力具有相似的pH依赖性。紫外线光谱中pH依赖性的变化表明柚皮素在高pH值下会电离成带负电的形式。由于最近发现nodD基因产物位于细胞质膜中（HRM Schlaman，HP Spaink，RJH Okker，和BJJ Lugtenberg，J.Bacteriol。，付印中），我们的数据与模型一致柚皮苷的非离子形式积聚在细胞质膜中，并以代谢不变的形式激活NodD蛋白。

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