Interchangeability and distinct properties of bacterial Fe-S cluster assembly systems:: Functional replacement of the isc and suf operons in Escherichia coli with the nifSU-like operon from Helicobacter pylori
Interchangeability and distinct properties of bacterial Fe-S cluster assembly systems:: Functional replacement of the isc and suf operons in Escherichia coli with the nifSU-like operon from Helicobacter pylori
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DOI：
10.1093/jb/mvh104
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发表时间：
2004-08-01
影响因子：
2.7
通讯作者：
Takahashi, Y
中科院分区：
文献类型：
--
作者：
Tokumoto, U;Kitamura, S;Takahashi, Y
铁-硫(Fe-S)簇的组装是铁-S蛋白翻译后成熟的关键步骤，它是由一个复杂的装置介导的。在大肠杆菌中，这一过程涉及两个独立的系统ISC和SuF，分别由iscSUA-hscBA-FDX基因簇和sufABCDSE操纵子编码。另一个被称为NIF(NifSU)的系统是固氮菌中固氮酶成熟所必需的。我们开发了一种新的遗传系统来进一步了解这些多组分系统，并确定ISC、SuF和Nif在Fe-S组装中的作用有何不同。我们已经构建了一个同时缺乏ISC和suf操纵子的大肠杆菌突变体，该菌株只有在存在互补质粒的情况下才能存活。利用质粒置换技术，我们检测了ISC和SuF操纵子，并鉴定了功能所必需的基因。此外，我们还发现从幽门螺杆菌克隆的nifSU类基因可以与ISC操纵子和suf操纵子进行功能互换。因此，NIF样系统参与了多种铁-S蛋白的成熟。在厌氧条件下，NIF补充ISC和SUF损失的能力增强。这可能解释了为什么NIF系统只存在于有限数量的细菌物种中，而大多数其他生物更喜欢ISC和/或SUF系统。虽然ISC和SUF在补充活性方面的差异很小，但在过氧化氢存在的情况下，SUF系统似乎更有利于细菌的生长。
The assembly of iron-sulfur (Fe-S) clusters, a key step in the post-translational maturation of Fe-S proteins, is mediated by a complex apparatus. In E. coli, this process involves two independent systems called ISC and SUF encoded by the iscSUA-hscBA-fdx gene cluster and sufABCDSE operon, respectively. Another system, termed NIF (nifSU), is required for the maturation of nitrogenase in nitrogen-fixing bacteria. We have developed a novel genetic system to gain further insight into these multi-component systems, and to determine how ISC, SUF and NIF might differ in their roles in Fe-S assembly. We have constructed an E. coli mutant lacking both the isc and suf operons, and this strain can only survive in the presence of a complementing plasmid. Using the plasmid replacement technique, we examined the isc and suf operons, and identified the genes essential for the function. Additionally, we have found that nifSU-like genes cloned from Helicobacter pylori are functionally exchangeable with the isc and suf operons. Thus, the NIF-like system participates in the maturation of a wide variety of Fe-S proteins. An increased ability of NIF to complement isc and suf loss was seen under anaerobic conditions. This may explain why the NIF system is only found in a limited number of bacterial species, and most other organisms prefer the ISC and/or SUF systems. While the differences between ISC and SUF were small with respect to the complementing activity, the SUF system appears to be more advantageous for bacterial growth in the presence of hydrogen peroxide.