Key Lab of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, China.
Environ Microbiol. 2011 May;13(5):1168-78. doi: 10.1111/j.1462-2920.2010.02416.x. Epub 2011 Jan 24.
Alcanivorax dieselolei strain B-5 is a marine bacterium that can utilize a broad range of n-alkanes (C(5) -C(36) ) as sole carbon source. However, the mechanisms responsible for this trait remain to be established. Here we report on the characterization of four alkane hydroxylases from A. dieselolei, including two homologues of AlkB (AlkB1 and AlkB2), a CYP153 homologue (P450), as well as an AlmA-like (AlmA) alkane hydroxylase. Heterologous expression of alkB1, alkB2, p450 and almA in Pseudomonas putida GPo12 (pGEc47ΔB) or P. fluorescens KOB2Δ1 verified their functions in alkane oxidation. Quantitative real-time RT-PCR analysis showed that these genes could be induced by alkanes ranging from C(8) to C(36) . Notably, the expression of the p450 and almA genes was only upregulated in the presence of medium-chain (C(8) -C(16) ) or long-chain (C(22) -C(36) ) n-alkanes, respectively; while alkB1 and alkB2 responded to both medium- and long-chain n-alkanes (C(12) -C(26) ). Moreover, branched alkanes (pristane and phytane) significantly elevated alkB1 and almA expression levels. Our findings demonstrate that the multiple alkane hydroxylase systems ensure the utilization of substrates of a broad chain length range.
柴油杆菌菌株 B-5 是一种海洋细菌，能够将广泛的正构烷烃（C(5) -C(36) ）作为唯一的碳源。然而，负责这一特性的机制仍有待确定。在这里，我们报告了来自 A. dieselolei 的四种烷烃羟化酶的特征，包括两种 AlkB 同源物（AlkB1 和 AlkB2）、一种 CYP153 同源物（P450）以及一种 AlmA 样（AlmA）烷烃羟化酶。alkB1、alkB2、p450 和 almA 在 Pseudomonas putida GPo12（pGEc47ΔB）或 P. fluorescens KOB2Δ1 中的异源表达验证了它们在烷烃氧化中的作用。定量实时 RT-PCR 分析表明，这些基因可以被从 C(8) 到 C(36) 的烷烃诱导。值得注意的是，p450 和 almA 基因的表达仅在存在中链（C(8) -C(16) ）或长链（C(22) -C(36) ）正构烷烃时才被上调；而 alkB1 和 alkB2 对中链和长链正构烷烃（C(12) -C(26) ）均有响应。此外，支链烷烃（姥鲛烷和植烷）显著提高了 alkB1 和 almA 的表达水平。我们的研究结果表明，多种烷烃羟化酶系统确保了对广泛链长范围的底物的利用。
