Malki S, De Luca G, Fardeau M L, Rousset M, Belaich J P, Dermoun Z
Biochimie et Ingéniérie des Protéines, Centre National de la Recherche Scientifique, F-13402 Marseille Cedex 20, France.
Arch Microbiol. 1997 Jan;167(1):38-45. doi: 10.1007/s002030050414.
The presence of one periplasmic [NiFe] hydrogenase, one periplasmic [Fe] hydrogenase, and one cytoplasmic NADP-reducing hydrogenase has been previously established in Desulfovibrio fructosovorans. In the present work, marker-exchange mutagenesis was performed to determine the function of the tetrameric NADP-reducing hydrogenase encoded by the hndA, B, C, and D genes. The mutations performed were not lethal to the cells, although the H2-dependent NADP reduction was completely abolished. The double-mutated DM4 (DeltahynABC, DeltahndD) strain was still able to grow on hydrogen plus sulfate as the sole energy source. The growth may have occurred under these culture conditions because of the presence of the remaining [Fe] hydrogenase. The cells grew differently on various substrates depending on whether fructose, lactate, or pyruvate was used in the presence of sulfate. The (hnd mutant growth rates were 25-70% lower than those of the wild-type strain, although the molar growth yield remained unchanged. By contrast, mutants devoid of both [NiFe] hydrogenase and NADP-reducing hydrogenase had 24-38% lower growth yields and showed a corresponding drop in the growth rates. We concluded that each of the three hydrogenases may contribute to the energy supply in D. fructosovorans and that the loss of one enzyme might be compensated for by another. However, the loss of two hydrogenases affected the phosphorylation accompanying the metabolism of fructose, lactate, and pyruvate.
先前已证实，嗜果糖脱硫弧菌中存在一种周质[NiFe]氢化酶、一种周质[Fe]氢化酶和一种细胞质NADP还原氢化酶。在本研究中，进行了标记交换诱变，以确定由hndA、B、C和D基因编码的四聚体NADP还原氢化酶的功能。尽管完全消除了H2依赖的NADP还原，但所进行的突变对细胞并非致命。双突变DM4（DeltahynABC，DeltahndD）菌株仍然能够以氢气加硫酸盐作为唯一能源生长。在这些培养条件下可能发生生长是因为存在剩余的[Fe]氢化酶。根据在硫酸盐存在下使用的是果糖、乳酸还是丙酮酸，细胞在各种底物上的生长情况有所不同。（hnd）突变体的生长速率比野生型菌株低25%-70%，尽管摩尔生长产量保持不变。相比之下，缺乏[NiFe]氢化酶和NADP还原氢化酶的突变体生长产量低24%-38%，并且生长速率相应下降。我们得出结论，三种氢化酶中的每一种都可能对嗜果糖脱硫弧菌的能量供应有贡献，并且一种酶的缺失可能由另一种酶来补偿。然而，两种氢化酶的缺失影响了果糖、乳酸和丙酮酸代谢过程中的磷酸化作用。
