The genomes of several Acinetobacter species possess three distinct polysaccharide-producing operons [two poly-N-acetyl glucosamine (PNAG) and one K-locus]. Using a microfluidic device, an increased amount of polysaccharides and enhanced biofilm formation were observed following continuous exposure to H2O2 and removal of the H2O2-sensing key regulator, OxyR, in Acinetobacter oleivorans DR1 cells. Gene expression analysis revealed that genes located in PNAG1, but not those in PNAG2, were induced and that genes in the K-locus were expressed in the presence of H2O2. Interestingly, the expression of the K-locus gene was enhanced in the PNAG1 mutant and vice versa. The absence of either OxyR or PNAG1 resulted in enhanced biofilm formation, higher surface hydrophobicity, and increased motility, implying that K-locus-driven polysaccharide production in both the oxyR and PNAG1 deletion mutants may be related to these phenotypes. Both the oxyR and K-locus deletion mutants were more sensitive to H2O2 compared with the wildtype and PNAG1 mutant strains. Purified OxyR binds to the promoter regions of both polysaccharide operons with a higher affinity toward the K-locus promoter. Although oxidized OxyR could bind to both promoter regions, the addition of dithiothreitol further enhanced the binding efficiency of OxyR, suggesting that OxyR might function as a repressor for controlling these polysaccharide operons.

中文翻译：

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OxyR控制的表面多糖的产生和油不动杆菌DR1中的生物膜形成。

一些不动杆菌属的基因组具有三个不同的产生多糖的操纵子[两个聚-N-乙酰氨基葡萄糖（PNAG）和一个K-基因座]。使用微流体装置，在油不动杆菌DR1细胞中连续暴露于H2O2并去除了H2O2感测关键调节剂OxyR之后，观察到了增加的多糖量和增强的生物膜形成。基因表达分析显示，诱导了位于PNAG1中的基因，而不诱导位于PNAG2中的基因，并且在H2O2存在的情况下K基因座中的基因被表达。有趣的是，在PNAG1突变体中K-基因座基因的表达增强了，反之亦然。OxyR或PNAG1的缺失导致生物膜形成增强，表面疏水性增强和运动性增强，暗示oxyR和PNAG1缺失突变体中由K位点驱动的多糖产生可能与这些表型有关。与野生型和PNAG1突变株相比，oxyR和K-基因座缺失突变株对H2O2的敏感性更高。纯化的OxyR以对K位基因启动子更高的亲和力与两个多糖操纵子的启动子区域结合。尽管氧化的OxyR可以结合到两个启动子区域，但添加二硫苏糖醇可进一步增强OxyR的结合效率，这表明OxyR可能起阻遏剂的作用，以控制这些多糖操纵子。纯化的OxyR以对K位基因启动子更高的亲和力与两个多糖操纵子的启动子区域结合。尽管氧化的OxyR可以结合到两个启动子区域，但添加二硫苏糖醇可进一步增强OxyR的结合效率，这表明OxyR可能起阻遏剂的作用，以控制这些多糖操纵子。纯化的OxyR以对K位基因启动子更高的亲和力与两个多糖操纵子的启动子区域结合。尽管氧化的OxyR可以结合到两个启动子区域，但添加二硫苏糖醇可进一步增强OxyR的结合效率，这表明OxyR可能起阻遏剂的作用，以控制这些多糖操纵子。