Fundamental role of cobalamin biosynthesis in the developmental growth of Streptomyces coelicolor A3 (2)
Fundamental role of cobalamin biosynthesis in the developmental growth of Streptomyces coelicolor A3 (2)
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DOI：
10.1007/s00253-014-6325-z
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发表时间：
2015-03
影响因子：
5
通讯作者：
H. Takano;Kenta Hagiwara;K. Ueda
中科院分区：
文献类型：
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作者：
H. Takano;Kenta Hagiwara;K. Ueda
钴胺(Cobalamin，Cbl)(代名词，维生素B12)是一种只由一些原核生物产生的含钴辅因子。为了研究Cbl合成在链霉菌中的作用，在天蓝色链霉菌A3(2)中产生了Cbl生物合成(COB)基因敲除突变体。突变株在富营养液中的生长与野生型相似，但在微量培养液中的生长受到抑制，提示Cb1参与了初级代谢的某些步骤。Cbl依赖的蛋氨酸合成酶甲硫氨酸催化的甲硫氨酸合成是候选方法之一。然而，添加蛋氨酸并没有挽救突变株的生长，这表明Cb1的可用性影响了另一种主要功能。转录分析证实，该突变体编码Cbl非依赖的蛋氨酸合成酶，可能是由于Cbl依赖的核糖开关机制。该突变株产生低水平的色素抗生素，并在丰富的培养基中形成较少的气生菌丝和孢子，这表明依赖Cbl的机制控制着发育。SCO4800基因敲除突变体也有类似的发育缺陷，编码Cbl依赖的异丁酰辅酶A变位酶(ICM)小亚基。由于ICM大亚基(SCO5415)的敲除不影响发育表型，SCO4800可能独立于SCO5415调节发育。有效的Cbl产生是复杂的Fs发育生命周期下各种功能的基础。天南星A3(2)。
Cobalamin (Cbl) (synonym, vitamin B12) is the cobalt-containing cofactor produced only by some prokaryotes.Streptomycesis an effective Cbl producer. To study the role of Cbl production inStreptomyces, a knockout mutant for Cbl biosynthesis (cob) was generated inStreptomyces coelicolorA3 (2). The growth of the mutant was similar to that of the wild type in a rich medium, but inhibited in minimal medium, suggesting the involvement of Cbl in some step of primary metabolism. Methionine synthesis catalyzed by MetH, the Cbl-dependent methionine synthase, is a candidate. However, supplementing the minimal medium with methionine did not rescue the growth of thecobmutant, indicating that the availability of Cbl affects another primary function. Transcriptional analysis confirmed that the mutant inducedmetEencoding an alternative Cbl-independent methionine synthase, probably due to the Cbl-dependent riboswitch mechanism. Thecobmutant produced low levels of pigment antibiotics and formed fewer aerial mycelium and spores in a rich medium, suggesting that a Cbl-dependent mechanism controls development. A similar developmental defect was observed for a knockout mutant for SCO4800, encoding the putative Cbl-dependent isobutyryl-CoA mutase (Icm) small subunit. Since the knockout of the Icm large subunit (SCO5415) did not affect the developmental phenotype, SCO4800 likely regulates development independently from SCO5415. Effective Cbl production is fundamental to the diverse functions underlying the complex developmental life cycle ofS. coelicolorA3 (2).