title: Cross-Regulation between the phz1 and phz2 Operons Maintain a Balanced Level of Phenazine Biosynthesis in Pseudomonas aeruginosa PAO1.
abstract: Gene duplication often provides selective advantages for the survival of microorganisms in adapting to varying environmental conditions. P. aeruginosa PAO1 possesses two seven-gene operons [phz1 (phzA1B1C1D1E1F1G1) and phz2 (phzA2B2C2D2E2F2G2)] that are involved in the biosynthesis of phenazine-1-carboxylic acid and its derivatives. Although the two operons are highly homologous and their functions are well known, it is unclear how the two phz operons coordinate their expressions to maintain the phenazine biosynthesis. By constructing single and double deletion mutants of the two phz operons, we found that the phz1-deletion mutant produced the same or less amount of phenazine-1-carboxylic acid and pyocyanin in GA medium than the phz2-knockout mutant while the phz1-phz2 double knockout mutant did not produce any phenazines. By generating phzA1 and phzA2 translational and transcriptional fusions with a truncated lacZ reporter, we found that the expression of the phz1 operon increased significantly at the post-transcriptional level and did not alter at the transcriptional level in the absence of the phz2 operon. Surprisingly, the expression the phz2 operon increased significantly at the post-transcriptional level and only moderately at the transcriptional level in the absence of the phz1 operon. Our findings suggested that a complex cross-regulation existed between the phz1 and phz2 operons. By mediating the upregulation of one phz operon expression while the other was deleted, this crosstalk would maintain the homeostatic balance of phenazine biosynthesis in P. aeruginosa PAO1.
authors.affiliation: Department of Applied and Environmental Microbiology, School of Biological Sciences, Ludong University, Yantai, China.|Department of Microbiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing, China.
authors.forename: Qinna
authors.initials: Q
authors.lastname: Cui
authors.affiliation: Department of Applied and Environmental Microbiology, School of Biological Sciences, Ludong University, Yantai, China.
authors.forename: Huinan
authors.initials: H
authors.lastname: Lv
authors.affiliation: Department of Applied and Environmental Microbiology, School of Biological Sciences, Ludong University, Yantai, China.
authors.forename: Zhuangzhuang
authors.initials: Z
authors.lastname: Qi
authors.affiliation: Department of Microbiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing, China.
authors.forename: Bei
authors.initials: B
authors.lastname: Jiang
authors.affiliation: Department of Applied and Environmental Microbiology, School of Biological Sciences, Ludong University, Yantai, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Xiao
authors.affiliation: Department of Applied and Environmental Microbiology, School of Biological Sciences, Ludong University, Yantai, China.
authors.forename: Linde
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Applied and Environmental Microbiology, School of Biological Sciences, Ludong University, Yantai, China.
authors.forename: Yihe
authors.initials: Y
authors.lastname: Ge
authors.affiliation: Department of Microbiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing, China.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Hu
mesh_terms: D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D004926:Escherichia coli; D009876:Operon / Q000235:genetics*; D010619:Phenazines / Q000737:chemistry / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D010619:Phenazines; D011994:Recombinant Proteins; C037165:1-phenazinecarboxylic acid