Alteration of the rugose phenotype in waaG and ddhC mutants of Salmonella enterica serovar typhimurium DT104 is associated with inverse production of curli and cellulose
Alteration of the rugose phenotype in waaG and ddhC mutants of Salmonella enterica serovar typhimurium DT104 is associated with inverse production of curli and cellulose
复制标题
DOI：
10.1128/aem.02868-05
复制
发表时间：
2006-07-01
影响因子：
4.4
通讯作者：
Joseph, Sam W.
中科院分区：
文献类型：
--
作者：
Anriany, Yuda;Sahu, Surashri N.;Joseph, Sam W.
鼠伤寒沙门氏菌DT104 Rv的皱缩（也称为起皱或rdar）表型与细胞聚集以及在低渗条件下低温形成菌膜和生物膜的能力有关。Rv中参与脂多糖（LPS）合成的两个基因ddhC（A1 - 8）和waaG（A1 - 9）的Tn5插入突变导致菌落皱缩性表达降低。扫描电子显微镜照片显示，与Rv相比，ddhC突变体的细胞外基质数量减少，而waaG突变体产生的基质则相对更多、更丰富。通过用抗AgfA（卷曲菌毛）抗体进行的蛋白质印迹分析判断，两种突变体产生的卷曲菌毛水平似乎都降低了，但令人惊讶的是，观察到它们相对于Rv纤维素含量增加。与不产生卷曲菌毛的突变体比较表明，卷曲菌毛产生的改变可能导致了纤维素含量的增加。虽然两种突变体在低渗富培养基中生长时生物膜形成受损，但当生长培养基中添加葡萄糖或葡萄糖与氯化钠的组合时，它们组成性地形成更多的生物膜。这些观察结果表明，LPS的改变可能对这些突变体的生物膜形成产生相反的影响，这取决于这些渗透调节物质的存在与否。在构建的鼠伤寒沙门氏菌LT2非极性缺失突变体中进一步证实了waaG突变体的表型，通过互补作用恢复了野生型表型。这些结果强调了完整的LPS在O -抗原和核心多糖水平上对卷曲蛋白和纤维素产生以及生物膜形成的调节的重要性，从而为控制鼠伤寒沙门氏菌多细胞行为的复杂调控系统增加了另一个潜在的组成部分。
The rugose (also known as wrinkled or rdar) phenotype in Salmonella enterica serovar Typhimurium DT104 Rv has been associated with cell aggregation and the ability, at low temperature under low-osmolarity conditions, to form pellicles and biofilms. Two Tn5 insertion mutations in genes that are involved in lipopolysaccharide (LPS) synthesis, ddhC (A1-8) and waaG (A1-9), of Rv resulted in diminished expression of colony rugosity. Scanning electron micrographs revealed that the ddhC mutant showed reduced amounts of extracellular matrix, while there was relatively more, profuse matrix production in the waaG mutant, compared to Rv. Both mutants appeared to produce decreased levels of curli, as judged by Western blot assays probed with anti-AgfA (curli) antibodies but, surprisingly, were observed to have increased amounts of cellulose relative to Rv. Comparison with a non-curli-producing mutant suggested that the alteration in curli production may have engendered the increased presence of cellulose. While both mutants had impaired biofilm formation when grown in rich medium with low osmolarity, they constitutively formed larger amounts of biofilms when the growth medium was supplemented with either glucose or a combination of glucose and NaCl. These observations indicated that LPS alterations may have opposing effects on biofilm formation in these mutants, depending upon either the presence or the absence of these osmolytes. The phenotypes of the waaG mutant were further confirmed in a constructed, nonpolar deletion mutant of S. enterica serovar Typhimurium LT2, where restoration to the wild-type phenotypes was accomplished by complementation. These results highlight the importance of an integral LPS, at both the O-antigen and core polysaccharide levels, in the modulation of curli protein and cellulose production, as well as in biofilm formation, thereby adding another potential component to the complex regulatory system which governs multicellular behaviors in S. enterica serovar Typhimurium.