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首页> 外文期刊>Journal of bacteriology >AlgX Is a Periplasmic Protein Required for Alginate Biosynthesis in Pseudomonas aeruginosa
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AlgX Is a Periplasmic Protein Required for Alginate Biosynthesis in Pseudomonas aeruginosa

机译：AlgX是铜绿假单胞菌藻酸盐生物合成所需的周质蛋白。

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Alginate, an exopolysaccharide produced by Pseudomonas aeruginosa, provides the bacterium with a selective advantage that makes it difficult to eradicate from the lungs of cystic fibrosis (CF) patients. Previous studies identified a gene, algX, within the alginate biosynthetic gene cluster on the P. aeruginosa chromosome. By probing cell fractions with anti-AlgX antibodies in a Western blot, AlgX was localized within the periplasm. Consistent with these results is the presence of a 26-amino-acid signal sequence. To examine the requirement for AlgX in alginate biosynthesis, part of algX in P. aeruginosa strain FRD1::pJLS3 was replaced with a nonpolar gentamicin resistance cassette. The resulting algXΔ::Gm mutant was verified by PCR and Western blot analysis and was phenotypically nonmucoid (non-alginate producing). The algXΔ::Gm mutant was restored to the mucoid phenotype with wild-type P. aeruginosa algX provided on a plasmid. The algXΔ::Gm mutant was found to secrete dialyzable oligouronic acids of various lengths. Mass spectroscopy and Dionex chromatography indicated that the dialyzable uronic acids are mainly mannuronic acid dimers resulting from alginate lyase (AlgL) degradation of polymannuronic acid. These studies suggest that AlgX is part of a protein scaffold that surrounds and protects newly formed polymers from AlgL degradation as they are transported within the periplasm for further modification and eventual transport out of the cell.
机译：藻酸是铜绿假单胞菌产生的一种胞外多糖，它为细菌提供了选择性优势，使其难以从囊性纤维化（CF）患者的肺部根除。先前的研究在 P的藻酸盐生物合成基因簇中鉴定了一个基因 algX 。铜绿染色体。通过在Western印迹中用抗AlgX抗体探测细胞级分，可以将AlgX定位在周质中。与这些结果一致的是存在26个氨基酸的信号序列。要检查藻酸盐生物合成中对AlgX的需求， P中的 algX 的一部分。用非极性庆大霉素抗性盒替换铜绿假单胞菌FRD1 :: pJLS3。所得的 algX Δ:: Gm突变体通过PCR和Western印迹分析进行了验证，并且在表型上为非粘液样（不产生藻酸盐）。 algX Δ:: Gm突变体恢复为具有野生型 P的粘液表型。质粒上提供了铜绿假单胞菌algX 。发现 algX Δ:: Gm突变体分泌各种长度的可透析低聚尿酸。质谱和Dionex色谱分析表明，可透析的糖醛酸主要是甘露糖酸二聚体，其是由聚甘露糖醛酸的藻酸盐裂解酶（AlgL）降解而产生的。这些研究表明，AlgX是蛋白质支架的一部分，该蛋白支架围绕并保护新形成的聚合物免遭AlgL降解，因为它们在周质中运输以进一步修饰并最终运输出细胞。

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