Sekine Mitsuo, Tanikawa Satoshi, Omata Seiha, Saito Mika, Fujisawa Takatomo, Tsukatani Naofumi, Tajima Takahisa, Sekigawa Tomohiro, Kosugi Hiroki, Matsuo Yasunori, Nishiko Rika, Imamura Kohsuke, Ito Mio, Narita Hitomi, Tago Shinichi, Fujita Nobuyuki, Harayama Shigeaki
NITE Genome Analysis Center, Department of Biotechnology, National Institute of Technology and Evaluation (NITE), Shibuya-ku, Tokyo, Japan.
Environ Microbiol. 2006 Feb;8(2):334-46. doi: 10.1111/j.1462-2920.2005.00899.x.
Rhodococcus erythropolis strain PR4 has been isolated as an alkane-degrading bacterium. The strain harbours one linear plasmid, pREL1 (271 577 bp) and two circular plasmids, pREC1 (104 014 bp) and pREC2 (3637 bp), all with some sequence similarities to other Rhodococcus plasmids. For pREL1, pREC1 and pREC2, 298, 102 and 3 open reading frames, respectively, were predicted. Linear plasmid pREL1 has several regions homologous to plasmid pBD2 found in R. erythropolis BD2. Sequence analysis of pREL1 and pBD2 identified common metal-resistance genes on both, but pREL1 also encodes alkane-degradation genes not found on pBD2, with enzyme constituents some of which are quite different from those of other organisms. The alkane hydroxylase consisted of a cytochrome P450 monooxygenase, a 2Fe-2S ferredoxin, and a ferredoxin reductase. The ferredoxin reductase amino acid sequence resembles the AlkT (rubredoxin reductase) sequence. A zinc-containing alcohol dehydrogenase further oxydizes alkanols, alkane oxidation products catalysed by alkane hydroxylase. Of the circular plasmids, the pREC1 sequence is partially similar to the sequence of pREAT701, the virulence plasmid found in Rhodococcus equi. pREC1 has no pREAT701 virulence genes and encodes genes for beta-oxidation of fatty acids. Thus, joint actions of enzymes encoded by pREL1 and pREC1 may enable efficient mineralization of alkanes.
红平红球菌PR4菌株已作为一种烷烃降解细菌被分离出来。该菌株含有一个线性质粒pREL1（271577 bp）和两个环状质粒pREC1（104014 bp）及pREC2（3637 bp），它们与其他红球菌质粒均有一些序列相似性。对于pREL1、pREC1和pREC2，分别预测出298、102和3个开放阅读框。线性质粒pREL1有几个区域与红平红球菌BD2中发现的质粒pBD2同源。pREL1和pBD2的序列分析确定了两者上的共同金属抗性基因，但pREL1还编码了pBD2上未发现的烷烃降解基因，其酶成分有些与其他生物的酶成分截然不同。烷烃羟化酶由一种细胞色素P450单加氧酶、一种2Fe-2S铁氧还蛋白和一种铁氧还蛋白还原酶组成。铁氧还蛋白还原酶氨基酸序列类似于AlkT（红素还原酶）序列。一种含锌乙醇脱氢酶进一步氧化烷醇，烷醇是由烷烃羟化酶催化的烷烃氧化产物。在环状质粒中，pREC1序列与马红球菌中发现的毒力质粒pREAT701的序列部分相似。pREC1没有pREAT701毒力基因，而是编码脂肪酸β-氧化的基因。因此，由pREL1和pREC1编码的酶的联合作用可能使烷烃能够有效矿化。
