Rhizobacter gummiphilus NS21 has two rubber oxygenases (RoxA and RoxB) acting synergistically in rubber utilisation
Rhizobacter gummiphilus NS21 has two rubber oxygenases (RoxA and RoxB) acting synergistically in rubber utilisation
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DOI：
10.1007/s00253-018-9341-6
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发表时间：
2018-12-01
影响因子：
5
通讯作者：
Jendrossek, Dieter
中科院分区：
文献类型：
--
作者：
Birke, Jakob;Roether, Wolf;Jendrossek, Dieter
革兰氏阴性菌对聚顺式-1,4-异戊二烯（橡胶）的生物降解研究仅在cummioxidans Steroidobacter 35Y（原Xanthomonas sp. 35Y）的酶促水平上进行。该物种产生两种橡胶加氧酶RoxA（35Y）和RoxB(35Y)，其中一种（RoxB(35Y)）将聚异戊二烯裂解为C-20和更高的低聚异戊二烯混合物，另一种（RoxA(35Y)）将聚异戊二烯和RoxB（35Y）衍生的低聚异戊二烯裂解为c -15-低聚异戊二烯类12-氧-4,8-二甲基三萜-4,8-二烯-1-al （ODTD）。ODTD可被甘油三酯吸收并作为碳源利用。革兰氏阳性橡胶降解细菌使用另一种橡胶加氧酶，乳胶清除蛋白（Lcp），用于聚异戊二烯分子的初始氧化攻击。在这篇文章中，我们研究了哪种类型的橡胶加氧酶存在于唯一其他有充分记录的革兰氏阴性橡胶降解物种——嗜胶根杆菌NS21中。在菌株NS21的基因组中没有发现Lcp蛋白的同源物，但发现了推测的RoxA蛋白和RoxB蛋白（后者与先前推测的lata命名的橡胶切割酶相同）的同源物。roxA（NS21）和roxB（NS21）基因分别在S. cummioxidans 35Y的roxA(35Y)/roxB（35Y）背景下表达，恢复突变体产生类寡异戊二烯的能力。分别纯化了RoxA（NS21）和RoxB（NS21）蛋白并进行了生化表征。结果结合数据库的硅分析表明，革兰氏阴性橡胶降解细菌通常利用两种协同作用的橡胶加氧酶（RoxA/RoxB）有效地将聚异戊二烯裂解为ODTD。
Biodegradation of poly(cis-1,4-isoprene) (rubber) by Gram-negative bacteria has been investigated on the enzymatic level only in Steroidobacter cummioxidans 35Y (previously Xanthomonas sp. 35Y). This species produces two kinds of rubber oxygenases, RoxA(35Y) and RoxB(35Y), one of which (RoxB(35Y)) cleaves polyisoprene to a mixture of C-20- and higher oligoisoprenoids while the other (RoxA(35Y)) cleaves polyisoprene and RoxB(35Y)-derived oligoisoprenoids to the C-15-oligoisoprenoid 12-oxo-4,8-dimethyltrideca-4,8-diene-1-al (ODTD). ODTD can be taken up by S. cummioxidans and used as a carbon source. Gram-positive rubber-degrading bacteria employ another type of rubber oxygenase, latex clearing protein (Lcp), for the initial oxidative attack of the polyisoprene molecule. In this contribution, we examined which type of rubber oxygenase is present in the only other well-documented Gram-negative rubber-degrading species, Rhizobacter gummiphilus NS21. No homologue for an Lcp protein but homologues for a putative RoxA and a RoxB protein (the latter identical to a previously postulated LatA-denominated rubber cleaving enzyme) were identified in the genome of strain NS21. The roxA(NS21) and roxB(NS21) genes were separately expressed in a roxA(35Y)/roxB(35Y) background of S. cummioxidans 35Y and restored the ability of the mutant to produce oligoisoprenoids. The RoxA(NS21) and RoxB(NS21) proteins were each purified and biochemically characterised. The resultsin combination with in silico analysis of databasesindicate that Gram-negative rubber-degrading bacteria generally utilise two synergistically acting rubber oxygenases (RoxA/RoxB) for efficient cleavage of polyisoprene to ODTD.