Barrière Charlotte, Veiga-da-Cunha Maria, Pons Nicolas, Guédon Eric, van Hijum Sacha A F T, Kok Jan, Kuipers Oscar P, Ehrlich Dusko S, Renault Pierre
Génétique Microbienne, Institut National de la Recherche Agronomique, 78352 Jouy-en-Josas cedex, France.
J Bacteriol. 2005 Jun;187(11):3752-61. doi: 10.1128/JB.187.11.3752-3761.2005.
In addition to its role as carbon and energy source, fructose metabolism was reported to affect other cellular processes, such as biofilm formation by streptococci and bacterial pathogenicity in plants. Fructose genes encoding a 1-phosphofructokinase and a phosphotransferase system (PTS) fructose-specific enzyme IIABC component reside commonly in a gene cluster with a DeoR family regulator in various gram-positive bacteria. We present a comprehensive study of fructose metabolism in Lactococcus lactis, including a systematic study of fru mutants, global messenger analysis, and a molecular characterization of its regulation. The fru operon is regulated at the transcriptional level by both FruR and CcpA and at the metabolic level by inducer exclusion. The FruR effector is fructose-1-phosphate (F1P), as shown by combined analysis of transcription and measurements of the intracellular F1P pools in mutants either unable to produce this metabolite or accumulating it. The regulation of the fru operon by FruR requires four adjacent 10-bp direct repeats. The well-conserved organization of the fru promoter region in various low-GC gram-positive bacteria, including CRE boxes as well as the newly defined FruR motif, suggests that the regulation scheme defined in L. lactis could be applied to these bacteria. Transcriptome profiling of fruR and fruC mutants revealed that the effect of F1P and FruR regulation is limited to the fru operon in L. lactis. This result is enforced by the fact that no other targets for FruR were found in the available low-GC gram-positive bacteria genomes, suggesting that additional phenotypical effects due to fructose metabolism do not rely directly on FruR control, but rather on metabolism.
除了作为碳源和能源的作用外，据报道果糖代谢还会影响其他细胞过程，例如链球菌的生物膜形成以及植物中的细菌致病性。编码1-磷酸果糖激酶和磷酸转移酶系统（PTS）果糖特异性酶IIABC组分的果糖基因通常与DeoR家族调节因子共同存在于各种革兰氏阳性细菌的基因簇中。我们对乳酸乳球菌中的果糖代谢进行了全面研究，包括对fru突变体的系统研究、全局信使分析及其调控的分子表征。fru操纵子在转录水平上受到FruR和CcpA的调控，在代谢水平上受到诱导物排除的调控。FruR效应物是果糖-1-磷酸（F1P），这是通过对无法产生这种代谢物或积累它的突变体中的转录和细胞内F1P池测量进行联合分析得出的。FruR对fru操纵子的调控需要四个相邻的10 bp直接重复序列。在各种低GC革兰氏阳性细菌中，fru启动子区域的保守组织，包括CRE框以及新定义的FruR基序，表明在乳酸乳球菌中定义的调控方案可能适用于这些细菌。fruR和fruC突变体的转录组分析表明，F1P和FruR调控的作用仅限于乳酸乳球菌中的fru操纵子。在可用的低GC革兰氏阳性细菌基因组中未发现FruR的其他靶标，这一事实强化了这一结果，表明果糖代谢引起的其他表型效应并不直接依赖于FruR控制，而是依赖于代谢。
