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首页> 外文期刊>Journal of bacteriology >Functional equivalence of Escherichia coli sigma E and Pseudomonas aeruginosa AlgU: E. coli rpoE restores mucoidy and reduces sensitivity to reactive oxygen intermediates in algU mutants of P. aeruginosa.
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Functional equivalence of Escherichia coli sigma E and Pseudomonas aeruginosa AlgU: E. coli rpoE restores mucoidy and reduces sensitivity to reactive oxygen intermediates in algU mutants of P. aeruginosa.

机译：大肠杆菌sigma E和铜绿假单胞菌AlgU的功能对等物：大肠杆菌rpoE可恢复粘液状并降低铜绿假单胞菌algU突变体对活性氧中间体的敏感性。

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Mucoid colony morphology is the result of the overproduction of the exopolysaccharide alginate and is considered to be a major pathogenic determinant expressed by Pseudomonas aeruginosa during chronic respiratory infections in cystic fibrosis. Conversion to mucoidy can be caused by mutations in the second or third gene of the stress-responsive system algU mucA mucB. AlgU is 66% identical to the alternative sigma factor RpoE (sigma E) from Escherichia coli and Salmonella typhimurium and directs transcription of several critical alginate biosynthetic and regulatory genes. AlgU is also required for the full resistance of P. aeruginosa to reactive oxygen intermediates and heat killing. In this work, we report that E. coli sigma E can complement phenotypic defects of algU inactivation in P. aeruginosa: (i) the rpoE gene from E. coli complemented an algU null mutant of P. aeruginosa to mucoidy; (ii) the presence of the E. coli rpoE gene in P. aeruginosa induced alginate production in the standard genetic nonmucoid strain PAO1; (iii) the plasmid-borne E. coli rpoE gene induced transcription of algD, a critical algU-dependent alginate biosynthetic gene; and (iv) when present in algU::Tcr mutants, E. coli rpoE partially restored resistance to paraquat, a redox cycling compound that increases intracellular levels of superoxide radicals. A new gene, mclA, encoding a polypeptide with an apparent molecular mass of 27.7 kDa was identified immediately downstream of rpoE in E. coli. The predicted product of this gene is 28% identical (72% similar) to MucA, a negative regulator of AlgU activity in P. aeruginosa. The results reported in this study demonstrate that RpoE and AlgU are functionally interchangeable in P. aeruginosa and suggest that elements showing sequence similarity to those known to regulate AlgU activity in P. aeruginosa are also present in other bacteria.
机译：粘液样菌落形态是胞外藻酸盐藻酸盐过量产生的结果，被认为是在囊性纤维化的慢性呼吸道感染期间由铜绿假单胞菌表达的主要致病因素。应激反应系统algU mucA mucB的第二个或第三个基因发生突变可导致转化为粘液状。 AlgU与大肠杆菌和鼠伤寒沙门氏菌的替代sigma因子RpoE（sigma E）具有66％的同一性，并指导几个关键藻酸盐生物合成和调控基因的转录。 AlgU也是铜绿假单胞菌对活性氧中间体和热杀灭的完全抵抗力所必需的。在这项工作中，我们报道了大肠杆菌sigma E可以补充铜绿假单胞菌中algU失活的表型缺陷：（i）来自大肠杆菌的rpoE基因将铜绿假单胞菌的algU无效突变体补充到粘液状; （ii）在标准遗传非粘液菌株PAO1中铜绿假单胞菌诱导的大肠杆菌rpoE基因的藻酸盐生产; （iii）质粒携带的大肠杆菌rpoE基因诱导algD的转录，algD是依赖algU的重要藻酸盐生物合成基因; （iv）当存在于algU :: Tcr突变体中时，大肠杆菌rpoE部分恢复了对百草枯的抗性，百草枯是一种氧化还原循环化合物，可增加细胞内超氧化物自由基的水平。在大肠杆菌中，在rpoE的紧接下游发现了一个新基因mclA，该基因编码表观分子量为27.7 kDa的多肽。该基因的预测产物与铜绿假单胞菌AlgU活性的负调节剂MucA 28％同一（72％相似）。该研究报告的结果表明，RpoE和AlgU在铜绿假单胞菌中具有功能互换性，并表明与其他已知在铜绿假单胞菌中调节AlgU活性的序列相似的元素也存在于其他细菌中。

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