Sabirova Julia S, Ferrer Manuel, Regenhardt Daniela, Timmis Kenneth N, Golyshin Peter N
Institute of Microbiology, Technical University of Braunschweig, Spielmannstrasse 7, D-38106 Braunschweig, Germany.
J Bacteriol. 2006 Jun;188(11):3763-73. doi: 10.1128/JB.00072-06.
Alcanivorax borkumensis is a ubiquitous marine petroleum oil-degrading bacterium with an unusual physiology specialized for alkane metabolism. This "hydrocarbonoclastic" bacterium degrades an exceptionally broad range of alkane hydrocarbons but few other substrates. The proteomic analysis presented here reveals metabolic features of the hydrocarbonoclastic lifestyle. Specifically, hexadecane-grown and pyruvate-grown cells differed in the expression of 97 cytoplasmic and membrane-associated proteins whose genes appeared to be components of 46 putative operon structures. Membrane proteins up-regulated in alkane-grown cells included three enzyme systems able to convert alkanes via terminal oxidation to fatty acids, namely, enzymes encoded by the well-known alkB1 gene cluster and two new alkane hydroxylating systems, a P450 cytochrome monooxygenase and a putative flavin-binding monooxygenase, and enzymes mediating beta-oxidation of fatty acids. Cytoplasmic proteins up-regulated in hexadecane-grown cells reflect a central metabolism based on a fatty acid diet, namely, enzymes of the glyoxylate bypass and of the gluconeogenesis pathway, able to provide key metabolic intermediates, like phosphoenolpyruvate, from fatty acids. They also include enzymes for synthesis of riboflavin and of unsaturated fatty acids and cardiolipin, which presumably reflect membrane restructuring required for membranes to adapt to perturbations induced by the massive influx of alkane oxidation enzymes. Ancillary functions up-regulated included the lipoprotein releasing system (Lol), presumably associated with biosurfactant release, and polyhydroxyalkanoate synthesis enzymes associated with carbon storage under conditions of carbon surfeit. The existence of three different alkane-oxidizing systems is consistent with the broad range of oil hydrocarbons degraded by A. borkumensis and its ecological success in oil-contaminated marine habitats.
博氏油食烷菌是一种广泛存在的海洋石油降解细菌，具有独特的生理特性，专门用于烷烃代谢。这种“烃降解”细菌能降解种类异常广泛的烷烃碳氢化合物，但很少降解其他底物。本文进行的蛋白质组学分析揭示了烃降解生活方式的代谢特征。具体而言，以十六烷为碳源生长的细胞和以丙酮酸为碳源生长的细胞在97种细胞质和膜相关蛋白的表达上存在差异，这些蛋白的基因似乎是46个假定操纵子结构的组成部分。在以烷烃为碳源生长的细胞中上调的膜蛋白包括三种能够通过末端氧化将烷烃转化为脂肪酸的酶系统，即由著名的alkB1基因簇编码的酶以及两个新的烷烃羟化系统，一个P450细胞色素单加氧酶和一个假定的黄素结合单加氧酶，还有介导脂肪酸β氧化的酶。在以十六烷为碳源生长的细胞中上调的细胞质蛋白反映了基于脂肪酸饮食的中心代谢，即乙醛酸循环支路和糖异生途径的酶，它们能够从脂肪酸提供关键的代谢中间体，如磷酸烯醇丙酮酸。它们还包括用于合成核黄素、不饱和脂肪酸和心磷脂的酶，这可能反映了膜为适应大量涌入的烷烃氧化酶引起的扰动而进行的结构重组。上调的辅助功能包括脂蛋白释放系统（Lol），可能与生物表面活性剂的释放有关，以及在碳过剩条件下与碳储存相关的聚羟基脂肪酸酯合成酶。三种不同烷烃氧化系统的存在与博氏油食烷菌降解的广泛石油烃范围及其在受油污染海洋栖息地的生态成功相一致。
