Pseudomonas protegens CHA0, known as plant-growth-promoting rhizobacterium, showed positive chemotactic responses toward proteinaceous L-amino acids. Genomic analysis revealed that P. protegens CHA0 possesses four putative chemoreceptors for amino acids (designated CtaA, CtaB, CtaC, and CtaD, respectively). Pseudomonas aeruginosa PCT2, a mutant defective in chemotaxis to amino acids, harboring a plasmid containing each of ctaA, ctaB, ctaC, and ctaD showed chemotactic responses to 20, 4, 4, and 11 types of amino acids, respectively. To enhance chemotaxis toward amino acids, we introduced the plasmids containing ctaA, ctaB, ctaC, or ctaD into P. protegens CHA0. By overexpression of the genes, we succeeded in enhancing chemotaxis toward more than half of the tested ligands. However, unexpectedly, the P. protegens CHA0 transformants showed unchanged or decreased responses to some amino acids when compared to wild-type CHA0. We speculate that alternation of expression of a chemoreceptor may affect the abundance of other chemoreceptors.

Abbreviations

cDNA: complementary DNA; LBD: ligand-binding domain; MCP: methyl-accepting chemotaxis protein; PDC: PhoQ/DcuS/CitA; PGPR: plant-growth-promoting rhizobacteria; qRT-PCR: quantitative reverse transcription PCR

中文翻译：

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促进植物生长的根瘤菌假单胞菌蛋白质CHA0中氨基酸的甲基接受趋化蛋白（MCP）的表征以及MCP基因过表达增强氨基酸趋化性。

假单胞菌蛋白质CHA0，被称为促进植物生长的根瘤菌，对蛋白质的L-氨基酸表现出正趋化反应。基因组学分析显示，蛋白质假单胞菌CHA0拥有四种假定的氨基酸化学感受器（分别称为CtaA，CtaB，CtaC和CtaD）。铜绿假单胞菌PCT2是一种氨基酸趋化缺陷型突变体，它含有一个包含ctaA，ctaB，ctaC和ctaD的质粒，分别显示出对20、4、4和11种氨基酸的趋化反应。为了增强朝向趋化氨基酸，我们介绍了含有质粒CTAA，CTAB，CTAC，或CTAD入P. protegensCHA0。通过基因的过表达，我们成功地增强了对一半以上测试配体的趋化性。但是，出乎意料的是，与野生型CHA0相比，蛋白质假单胞菌CHA0转化株对某些氨基酸的反应未发生变化或下降。我们推测化学感受器表达的改变可能会影响其他化学感受器的丰度。

缩略语

cDNA：互补DNA；LBD：配体结合结构域；MCP：甲基接受趋化蛋白；PDC：PhoQ / DcuS / CitA；PGPR：促进植物生长的根瘤菌；qRT-PCR：定量逆转录PCR