Koeduka Takao, Kajiwara Tadahiko, Matsui Kenji
Department of Biological Chemistry, Faculty of Agriculture, and Applied Molecular Bioscience, Graduate School of Medicine, Yamaguchi University, Yoshida 1677-1, Yamaguchi, 753-8515, Japan.
Curr Microbiol. 2007 Apr;54(4):315-9. doi: 10.1007/s00284-006-0512-9. Epub 2007 Mar 12.
Oxylipin metabolism represents one of the important hormonal and defensive mechanisms employed by plants, algae, or animals. It begins mostly with the reaction of lipoxygenases (LOXs), which catalyze the oxygenation of polyunsaturated fatty acids to form the corresponding hydroperoxides. At present, little information about LOXs in cyanobacteria has been reported. Herein, we report the first isolation of two LOX genes (NpLOX1 and NpLOX2) from a cyanobacterium, Nostoc punctiforme ATCC29133. Incubations of recombinant NpLOX1 and NpLOX2 proteins expressed in Eschelichia coli with linoleic acid resulted in the predominant formation of linoleic acid 13-S-hydroperoxide. Other C18 and C20 fatty acids could also be substrates for NpLOX enzymes. Phylogenetic analysis of NpLOX sequences showed that the NpLOX enzymes shared a high homology with LOX sequence of a bacterial pathogen, Pseudomonas aeruginosa, and these bacterial LOXs formed a subfamily distinct from those of plants, algae, and mammals.
氧化脂质代谢是植物、藻类或动物所采用的重要激素和防御机制之一。它主要始于脂氧合酶（LOXs）的反应，脂氧合酶催化多不饱和脂肪酸的氧化，形成相应的氢过氧化物。目前，关于蓝细菌中脂氧合酶的信息报道较少。在此，我们报告了首次从点状念珠藻ATCC29133中分离出两个脂氧合酶基因（NpLOX1和NpLOX2）。在大肠杆菌中表达的重组NpLOX1和NpLOX2蛋白与亚油酸一起孵育，导致主要形成亚油酸13-S-氢过氧化物。其他C18和C20脂肪酸也可能是NpLOX酶的底物。对NpLOX序列的系统发育分析表明，NpLOX酶与细菌病原体铜绿假单胞菌的LOX序列具有高度同源性，并且这些细菌脂氧合酶形成了一个与植物、藻类和哺乳动物的脂氧合酶不同的亚家族。
