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首页> 外文期刊>Applied and Environmental Microbiology >Competitive inhibition of an energy-dependent nickel transport system by divalent cations in Bradyrhizobium japonicum JH.
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Competitive inhibition of an energy-dependent nickel transport system by divalent cations in Bradyrhizobium japonicum JH.

机译：短枝根瘤菌JH中的二价阳离子竞争性抑制能量依赖性镍转运系统。

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摘要

Both nickel-specific transport and nickel transport by a magnesium transporter have been described previously for a variety of nickel-utilizing bacteria. The derepression of hydrogenase activity in Bradyzhizobium japonicum JH and in a gene-directed mutant of strain JH (in an intracellular Ni metabolism locus), strain JHK7, was inhibited by MgSO4. For both strains, Ni2+ uptake was also markedly inhibited by Mg2+, and the Mg(2+)-mediated inhibition could be overcome by high levels of Ni2+ provided in the assay buffer. The results indicate that both B. japonicum strains transport Ni2+ via a high-affinity magnesium transport system. Dixon plots (1/V versus inhibitor) showed that the divalent cations Co2+, Mn2+, and Zn2+, like Mg2+, were competitive inhibitors of Ni2+ uptake. The KiS for nickel uptake inhibition by Mg2+, Co2+, Mn2+, and Zn2+ were 48, 22, 12, and 8 microM, respectively. Cu2+ strongly inhibited Ni2+ uptake, and molybdate inhibited it slightly. Respiratory inhibitors cyanide and azide, the uncoupler carbonyl cyanide m-chlorophenylhydrazone, the ATPase inhibitor N,N'-dicyclohexylcarbodiimide, and ionophores nigericin and valinomycin significantly inhibited short-term (5 min) Ni2+ uptake, showing that Ni2+ uptake in strain JH is energy dependent. Most of these conclusions are quite different from those reported previously for a different B. japonicum strain belonging to a different serogroup.
机译：先前已经针对多种利用镍的细菌描述了镍特异性转运和通过镁转运蛋白的镍转运。硫酸根抑制了日本慢杆菌JH和菌株JH（在细胞内Ni代谢位点）菌株JHK7的基因定向突变体中的氢化酶活性的抑制。对于这两个菌株，Ni2 +的摄取也被Mg2 +显着抑制，并且Mg（2+）介导的抑制作用可以通过测定缓冲液中提供的高水平Ni2 +克服。结果表明，两个日本芽孢杆菌菌株均通过高亲和力镁转运系统转运Ni2 +。 Dixon图（1 / V对抑制剂）表明，二价阳离子Co2 +，Mn2 +和Zn2 +与Mg2 +一样，是Ni2 +吸收的竞争性抑制剂。 Mg2 +，Co2 +，Mn2 +和Zn2 +抑制镍吸收的KiS分别为48、22、12和8 microM。 Cu2 +强烈抑制了Ni2 +的吸收，而钼酸盐略微抑制了它的吸收。呼吸抑制剂氰化物和叠氮化物，解偶联剂羰基氰化物间氯苯hydr，ATPase抑制剂N，N'-二环己基碳二亚胺以及离子载体尼日菌和缬霉素均显着抑制短期（5分钟）Ni2 +的吸收，表明JH菌株吸收的Ni2 +是能量。依赖。这些结论中的大多数与先前报道的属于不同血清群的不同日本血吸虫菌株的结论完全不同。

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