Virulence, resistance to magainin II, and expression of pectate lyase are controlled by the PhoP-PhoQ two-component regulatory system responding to pH and magnesium in Erwinia chrysanthemi 3937
Virulence, resistance to magainin II, and expression of pectate lyase are controlled by the PhoP-PhoQ two-component regulatory system responding to pH and magnesium in Erwinia chrysanthemi 3937
复制标题
DOI：
10.1007/s10327-004-0158-z
复制
发表时间：
2005-02-01
影响因子：
1.2
通讯作者：
Tsuyumu, Shinji
中科院分区：
文献类型：
--
作者：
Haque, Md. Manjurul;Tsuyumu, Shinji
在低Mg ~（2+）浓度和酸性或中性pH条件下，欧文氏菌3937菌株的phoP和phoQ标记交换突变体对阳离子抗菌肽（CAMP）magainin Ⅱ的敏感性均高于野生型。在高Mg ~（2+）和酸性pH条件下，只有phoQ突变体对magainin Ⅱ的敏感性高于野生型，而phoP突变体对magainin Ⅱ的敏感性则无明显差异;在低Mg ~（2+）和中性pH条件下，野生型菌株在含有植物提取物和聚半乳糖醛酸（PGA）的培养基中Pel的合成受到了超诱导，而在高Mg ~（2+）和中性pH条件下，突变体菌株没有Pel的合成受到超诱导。浸渍也大大减少了这些突变体相比，野生型时，接种物进行预培养，然后再悬浮在培养基中与低Mg 2+在中性pH值。然而，当细菌进行预培养，再悬浮在培养基中与高Mg 2+在中性pH值，严重浸渍观察到在这些突变体，但不是在野生型。因此，在低Mg 2+时，PhoP-PhoQ TCS似乎被刺激浸渍和Pel合成的超诱导。然而，在高Mg 2+下，这些表型可能会抑制PhoP-PhoQ TCS，并且PhoP可能受PhoQ调节以外的机制控制。
Marker-exchanged mutants of phoP and phoQ of Erwinia chrysanthemi (Ech) strain 3937 became more sensitive to the cationic antimicrobial peptide (CAMP) magainin II than did the wild type at a low Mg2+ concentration and at either acidic or neutral pH. At high Mg2+ and acidic pH, only the phoQ mutant, but not the phoP mutant, became more sensitive to magainin II than did the wild type; both mutants were more sensitive at neutral pH. The hyperinduction of Pel synthesis in medium containing plant extracts and polygalacturonic acid (PGA) was confirmed in the wild type but not in the mutants at low Mg2+ and neutral pH. However, Pel was hyperinduced at high Mg2+ and neutral pH in these mutants but not in the wild type. Maceration was also greatly reduced by these mutants compared to the wild type when the inoculum was precultured and then resuspended in the medium with low Mg2+ at neutral pH. However, when bacteria were precultured and resuspended in the medium with high Mg2+ at neutral pH, severe maceration was observed in these mutants but not in the wild type. Thus, at low Mg2+, PhoP-PhoQ TCS seems to be stimulated for maceration and the hyperinduction of Pel synthesis. At high Mg2+, however, PhoP-PhoQ TCS may be repressed for these phenotypes, and PhoP may be controlled by a mechanism(s) other than PhoQ regulation.