Byers David M, Shen Zhiwei
The Atlantic Research Centre, Department of Pediatrics, Dalhousie University, C-305, Clinical Research Centre, 5849 University Avenue, Halifax, NS B3H 4H7, Canada.
Can J Microbiol. 2002 Oct;48(10):933-9. doi: 10.1139/w02-092.
The bioluminescent marine bacterium, Vibrio harveyi, can utilize exogenous myristic acid (14:0) for beta-oxidation, phospholipid and lipid A synthesis, and as an source of myristyl aldehyde for light emission in the V. harveyi dark mutant M17. A variety of genetic and biochemical strategies were employed in an attempt to isolate V. harveyi mutants defective in myristate uptake and to characterize proteins involved in this process. Although [3H]myristate uptake in a tritium suicide experiment decreased the survival of nitrosoguanidine-treated M17 cells by a factor of 10(5), none of the surviving cells characterized were defective in either incorporation of exogenous myristate into phospholipid or stimulation of light emission. These parameters were also unaffected when intact M17 cells were treated with proteases. Moreover, M17 double mutants selected on the basis of diminished luminescence response to myristate all incorporated [3H]myristate into lipids normally. Finally, no resistant colonies were obtained using the bacteriocidal fatty acid analogue, 11-bromoundecanoate, and experiments with decanoate (10:0) indicated that the V. harveyi cell envelope is very sensitive to physical disruption by fatty acids. Taken together, these results support an unfacilitated uptake of myristic acid in V. harveyi, in contrast with the regulated vectorial transport and activation of long chain fatty acids in Escherichia coli.
发光海洋细菌哈氏弧菌（Vibrio harveyi）能够利用外源肉豆蔻酸（14:0）进行β-氧化、磷脂和脂多糖合成，并作为肉豆蔻醛的来源在哈氏弧菌黑暗突变体M17中用于发光。我们采用了多种遗传和生化策略，试图分离出肉豆蔻酸摄取缺陷的哈氏弧菌突变体，并对参与这一过程的蛋白质进行表征。尽管在氚自杀实验中[3H]肉豆蔻酸摄取使经亚硝基胍处理的M17细胞的存活率降低了10^5倍，但所鉴定的存活细胞中没有一个在将外源肉豆蔻酸掺入磷脂或刺激发光方面存在缺陷。当完整的M17细胞用蛋白酶处理时，这些参数也不受影响。此外，基于对肉豆蔻酸的发光反应减弱而选择的M17双突变体都能正常地将[3H]肉豆蔻酸掺入脂质中。最后，使用杀菌脂肪酸类似物11-溴代十一烷酸未获得抗性菌落，并且用癸酸（10:0）进行的实验表明哈氏弧菌的细胞膜对脂肪酸引起的物理破坏非常敏感。综上所述，这些结果支持哈氏弧菌中肉豆蔻酸的摄取是不依赖转运蛋白的，这与大肠杆菌中长链脂肪酸的调节性向量运输和激活形成对比。
