Bacteria that inhabit soils and the leaves of trees partially mitigate the release of the abundant volatile organic compound, isoprene (2-methyl-1,3-butadiene). While the initial steps of isoprene metabolism were identified in Rhodococcus sp. AD45 two decades ago, the isoprene metabolic pathway still remains largely undefined. Limited understanding of the functions of isoG, isoJ and aldH and uncertainty in the route of isoprene-derived carbon into central metabolism have hindered our understanding of isoprene metabolism. These previously uncharacterised iso genes are essential in Variovorax sp. WS11, determined by targeted mutagenesis. Using combined ‘omics-based approaches, we propose the complete isoprene metabolic pathway. Isoprene is converted to propionyl-CoA, which is assimilated by the chromosomally encoded methylmalonyl-CoA pathway, requiring biotin and vitamin B12, with the plasmid-encoded methylcitrate pathway potentially providing robustness against limitations in these vitamins. Key components of this pathway were induced by both isoprene and its initial oxidation product, epoxyisoprene, the principal inducer of isoprene metabolism in both Variovorax sp. WS11 and Rhodococcus sp. AD45. Analysis of the genomes of distinct isoprene-degrading bacteria indicated that all of the genetic components of the methylcitrate and methylmalonyl-CoA pathways are not always present in isoprene degraders, although incorporation of isoprene-derived carbon via propionyl-CoA and acetyl-CoA is universally indicated.

中文翻译：

---

'组学指导的异戊二烯代谢途径预测 Variovorax sp。WS11

栖息在土壤和树叶中的细菌部分地减轻了丰富的挥发性有机化合物异戊二烯（2-甲基-1,3-丁二烯）的释放。虽然异戊二烯代谢的初始步骤是在Rhodococcus sp。AD45 二十年前，异戊二烯代谢途径在很大程度上仍未明确。对isoG、isoJ和aldH功能的有限了解以及异戊二烯衍生碳进入中心代谢途径的不确定性阻碍了我们对异戊二烯代谢的理解。这些以前未表征的iso基因在Variovorax中是必不可少的sp。WS11，通过靶向诱变确定。使用组合的基于组学的方法，我们提出了完整的异戊二烯代谢途径。异戊二烯转化为丙酰辅酶 A，丙酰辅酶 A 被染色体编码的甲基丙二酰辅酶 A 途径同化，需要生物素和维生素 B12，而质粒编码的柠檬酸甲酯途径可能对这些维生素的限制提供稳健性。该途径的关键成分由异戊二烯及其初始氧化产物环氧异戊二烯诱导，环氧异戊二烯是Variovorax sp. 中异戊二烯代谢的主要诱导剂。WS11 和红球菌属sp。公元 45 年。对不同异戊二烯降解细菌的基因组分析表明，甲基柠檬酸和甲基丙二酰辅酶 A 途径的所有遗传成分并不总是存在于异戊二烯降解物中，尽管异戊二烯衍生碳通过丙酰辅酶 A 和乙酰辅酶 A 的掺入普遍存在表明的。