LuxS-independent formation of AI-2 from ribulose-5-phosphate.
LuxS-independent formation of AI-2 from ribulose-5-phosphate.
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DOI：
10.1186/1471-2180-8-98
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发表时间：
2008-06-18
期刊：
影响因子：
4.2
通讯作者：
Winzer K
中科院分区：
文献类型：
--
作者：
Tavender TJ;Halliday NM;Hardie KR;Winzer K
在许多细菌中，信号分子AI-2是在由酶LuxS催化的反应中从其前体S-核糖基-L-高半胱氨酸产生的。然而，也报道了缺乏luxS基因的生物体产生AI-2样活性，最近通过随机建模预测了大肠杆菌中AI-2形成的替代途径的存在。在此，我们研究了在缺乏luxS的情况下，核酮糖-5-磷酸的自发转化可能是AI-2产生的原因的可能性。在与体内报道的浓度相似的浓度下孵育后，发现5-磷酸核酮糖而不是5-磷酸核糖的缓冲溶液含有高水平的AI-2活性。为了测试该过程是否有助于细菌细胞在体内形成AI-2，使用了改进的哈氏弧菌生物测定法。与前人研究结果一致，E.发现大肠杆菌和金黄色葡萄球菌luxS突变体不含有可检测水平的AI-2活性。然而，在E. coli pgi-eda-edd-luxS突变株，该菌株通过氧化磷酸戊糖途径完全降解葡萄糖，以核酮糖-5-磷酸作为必需的中间体。我们的结果表明，通过核酮糖-5-磷酸的自发转化，AI-2的LuxS非依赖性形成可能确实在体内发生。它对野生型E中AI-2的形成没有贡献。coli和革兰氏阳性菌S.金黄色葡萄球菌，但可能是缺乏luxS基因的其它生物体所报道的AI-2样活性的原因。
In many bacteria, the signal molecule AI-2 is generated from its precursor S-ribosyl-L-homocysteine in a reaction catalysed by the enzyme LuxS. However, generation of AI-2-like activity has also been reported for organisms lacking the luxS gene and the existence of alternative pathways for AI-2 formation in Escherichia coli has recently been predicted by stochastic modelling. Here, we investigate the possibility that spontaneous conversion of ribulose-5-phosphate could be responsible for AI-2 generation in the absence of luxS. Buffered solutions of ribulose-5-phosphate, but not ribose-5-phosphate, were found to contain high levels of AI-2 activity following incubation at concentrations similar to those reported in vivo. To test whether this process contributes to AI-2 formation by bacterial cells in vivo, an improved Vibrio harveyi bioassay was used. In agreement with previous studies, culture supernatants of E. coli and Staphylococcus aureus luxS mutants were found not to contain detectable levels of AI-2 activity. However, low activities were detected in an E. coli pgi-eda-edd-luxS mutant, a strain which degrades glucose entirely via the oxidative pentose phosphate pathway, with ribulose-5-phosphate as an obligatory intermediate. Our results suggest that LuxS-independent formation of AI-2, via spontaneous conversion of ribulose-5-phosphate, may indeed occur in vivo. It does not contribute to AI-2 formation in wildtype E. coli and S. aureus under the conditions tested, but may be responsible for the AI-2-like activities reported for other organisms lacking the luxS gene.
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