Transcriptional Profiling of Nitrogen Fixation in Azotobacter vinelandii
Transcriptional Profiling of Nitrogen Fixation in Azotobacter vinelandii
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DOI：
10.1128/jb.05099-11
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发表时间：
2011-09-01
影响因子：
3.2
通讯作者：
Peters, John W.
中科院分区：
文献类型：
--
作者：
Hamilton, Trinity L.;Ludwig, Marcus;Peters, John W.
大多数生物固氮(N-2)是由一种依赖钼的固氮酶的活性产生的，这是一种复杂的铁硫酶，与多种细菌和一些产甲烷古菌有关。棕色固氮细菌是一种专性好氧细菌，它通过氧敏感的钼固氮酶固定氮，但当钼限制时，也能够通过遗传上不同的替代形式的固氮酶的活动固定氮，该固氮酶被称为VNF和ANF系统。VnF系统似乎用V取代了Mo，而ANF系统被认为包含Fe作为各自活性中心金属因子中唯一的过渡金属。先前的遗传分析表明，VNF和ANF系统中涉及许多NIF编码的成分。在不同的金属修饰剂(如钼或钒)下，在固氮条件下培养的棕色拟青霉的全基因组转录图谱揭示了与每个固氮酶系统相关的基因的离散互补以及系统之间的串扰程度。此外，没有直接参与N-2固定的基因转录水平的变化提供了对这种专性好氧菌中中枢代谢过程和N-2固定的氧敏感过程的整合的洞察。这些结果强调了依赖于钼和不依赖于钼的重氮化生长的显著差异，这突出了在存在钼的情况下重氮化生长的显著优势。
Most biological nitrogen (N-2) fixation results from the activity of a molybdenum-dependent nitrogenase, a complex iron-sulfur enzyme found associated with a diversity of bacteria and some methanogenic archaea. Azotobacter vinelandii, an obligate aerobe, fixes nitrogen via the oxygen-sensitive Mo nitrogenase but is also able to fix nitrogen through the activities of genetically distinct alternative forms of nitrogenase designated the Vnf and Anf systems when Mo is limiting. The Vnf system appears to replace Mo with V, and the Anf system is thought to contain Fe as the only transition metal within the respective active site metallocofactors. Prior genetic analyses suggest that a number of nif-encoded components are involved in the Vnf and Anf systems. Genome-wide transcription profiling of A. vinelandii cultured under nitrogen-fixing conditions under various metal amendments (e.g., Mo or V) revealed the discrete complement of genes associated with each nitrogenase system and the extent of cross talk between the systems. In addition, changes in transcript levels of genes not directly involved in N-2 fixation provided insight into the integration of central metabolic processes and the oxygen-sensitive process of N-2 fixation in this obligate aerobe. The results underscored significant differences between Mo-dependentand Mo-independent diazotrophic growth that highlight the significant advantages of diazotrophic growth in the presence of Mo.