Ollinger Juliane, Wiedmann Martin, Boor Kathryn J
Department of Food Science, Cornell University, Ithaca, New York 14853, USA.
Foodborne Pathog Dis. 2008 Jun;5(3):281-93. doi: 10.1089/fpd.2008.0079.
Mounting evidence suggests that sigma(B) and PrfA coregulate transcription of multiple genes in Listeria monocytogenes, therefore, the relative contributions of sigma(B) and PrfA to transcript levels of genes identified previously as differentially regulated by PrfA were measured. Group I genes are recognized virulence genes that are positively regulated by PrfA; group II genes were reported previously as negatively regulated by PrfA; and multiple group III genes were proposed to be coregulated by sigma(B) and PrfA. Transcript levels for selected genes were measured by quantitative reverse transcriptase polymerase chain reaction (RT-PCR) in L. monocytogenes 10403S as well as in otherwise isogenic DeltasigB, DeltaprfA, and DeltasigBDeltaprfA strains grown under conditions demonstrated to induce either PrfA activity (0.2% activated charcoal) or both PrfA and sigma(B) activity (stationary phase). Although the Group I gene plcA was positively regulated by PrfA, transcript levels for the group II genes lmo0278 and lmo0178 were not affected by the prfA deletion. While the sigB deletion significantly affected transcript levels for the selected group III genes (i.e., lmo0596, lmo0654, bsh, and opuCA), with lower transcript levels in the DeltasigB strains under all conditions tested, transcript levels for these genes were not significantly affected by the prfA deletion. Our results suggest that the regulatory interactions between PrfA and sigma(B) contribute to PrfA's predominant role as a direct regulator of virulence genes critical for invasion and intracellular survival in L. monocytogenes 10403S, while sigma(B) regulates a wider range of virulence and stress response genes.
越来越多的证据表明，σ(B)和PrfA共同调控单核细胞增生李斯特菌中多个基因的转录，因此，我们测定了σ(B)和PrfA对先前鉴定为受PrfA差异调控的基因转录水平的相对贡献。第一组基因是公认的毒力基因，受PrfA正调控；第二组基因先前报道受PrfA负调控；多组第三组基因被认为受σ(B)和PrfA共同调控。通过定量逆转录聚合酶链反应（RT-PCR）测定单核细胞增生李斯特菌10403S以及在其他方面同基因的ΔsigB、ΔprfA和ΔsigBΔprfA菌株中选定基因的转录水平，这些菌株在已证明可诱导PrfA活性（0.2%活性炭）或PrfA和σ(B)活性（稳定期）的条件下生长。虽然第一组基因plcA受PrfA正调控，但第二组基因lmo0278和lmo0178的转录水平不受prfA缺失的影响。虽然sigB缺失显著影响选定的第三组基因（即lmo0596、lmo0654、bsh和opuCA）的转录水平，在所有测试条件下ΔsigB菌株中的转录水平较低，但这些基因的转录水平不受prfA缺失的显著影响。我们的结果表明，PrfA和σ(B)之间的调控相互作用有助于PrfA在单核细胞增生李斯特菌10403S中作为对侵袭和细胞内存活至关重要的毒力基因的直接调节因子发挥主要作用，而σ(B)调节更广泛的毒力和应激反应基因。
