Kasai Daisuke, Imai Shunsuke, Asano Shota, Tabata Michiro, Iijima So, Kamimura Naofumi, Masai Eiji, Fukuda Masao
a Department of Bioengineering , Nagaoka University of Technology , Nagaoka , Japan.
Biosci Biotechnol Biochem. 2017 Mar;81(3):614-620. doi: 10.1080/09168451.2016.1263147. Epub 2017 Jan 23.
A Gram-negative rubber-degrading bacterium, Rhizobacter gummiphilus NS21 grew and produced aldehyde metabolites on a deproteinized natural rubber (DPNR)-overlay agar medium forming a clearing zone. A transposon-insertion mutant, which had lost the ability to degrade DPNR, was isolated to identify the rubber degradation genes. Sequencing analysis indicated that the transposon was inserted into a putative oxygenase gene, latA. The deduced amino acid sequence of latA has 36% identity with that of roxA, which encodes a rubber oxygenase of Xanthomonas sp. strain 35Y. Phylogenetic analysis revealed that LatA constitutes a distinct group from RoxA. Heterologous expression in a Methylibium host and deletion analysis of latA indicated that the latA product is responsible for the depolymerization of DPNR. The quantitative reverse transcription-PCR analysis indicated that the transcription of latA is induced during the growth on DPNR. These results strongly suggest that latA is directly involved in the degradation of rubber in NS21.
革兰氏阴性橡胶降解菌胶生根瘤菌NS21在脱蛋白天然橡胶（DPNR）覆盖的琼脂培养基上生长并产生醛类代谢产物，形成一个透明圈。分离出一株失去降解DPNR能力的转座子插入突变体，以鉴定橡胶降解基因。测序分析表明，转座子插入到一个假定的加氧酶基因latA中。latA推导的氨基酸序列与编码黄单胞菌属菌株35Y橡胶加氧酶的roxA具有36%的同一性。系统发育分析表明，LatA与RoxA构成一个不同的群体。在甲基营养菌宿主中的异源表达和latA的缺失分析表明，latA产物负责DPNR的解聚。定量逆转录PCR分析表明，latA的转录在DPNR上生长期间被诱导。这些结果强烈表明，latA直接参与NS21中橡胶的降解。
