title: Pseudomonas aeruginosa IscR-Regulated Ferredoxin NADP(+) Reductase Gene (fprB) Functions in Iron-Sulfur Cluster Biogenesis and Multiple Stress Response.
abstract: P. aeruginosa (PAO1) has two putative genes encoding ferredoxin NADP(+) reductases, denoted fprA and fprB. Here, the regulation of fprB expression and the protein's physiological roles in [4Fe-4S] cluster biogenesis and stress protection are characterized. The fprB mutant has defects in [4Fe-4S] cluster biogenesis, as shown by reduced activities of [4Fe-4S] cluster-containing enzymes. Inactivation of the gene resulted in increased sensitivity to oxidative, thiol, osmotic and metal stresses compared with the PAO1 wild type. The increased sensitivity could be partially or completely suppressed by high expression of genes from the isc operon, which are involved in [Fe-S] cluster biogenesis, indicating that stress sensitivity in the fprB mutant is partially caused by a reduction in levels of [4Fe-4S] clusters. The pattern and regulation of fprB expression are in agreement with the gene physiological roles; fprB expression was highly induced by redox cycling drugs and diamide and was moderately induced by peroxides, an iron chelator and salt stress. The stress-induced expression of fprB was abolished by a deletion of the iscR gene. An IscR DNA-binding site close to fprB promoter elements was identified and confirmed by specific binding of purified IscR. Analysis of the regulation of fprB expression supports the role of IscR in directly regulating fprB transcription as a transcription activator. The combination of IscR-regulated expression of fprB and the fprB roles in response to multiple stressors emphasizes the importance of [Fe-S] cluster homeostasis in both gene regulation and stress protection.
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Adisak
authors.initials: A
authors.lastname: Romsang
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.
authors.forename: Jintana
authors.initials: J
authors.lastname: Duang-Nkern
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Wilaiwan
authors.initials: W
authors.lastname: Wirathorn
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand; Center of Excellence on Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand; Program in Applied Biological Science: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand.
authors.forename: Paiboon
authors.initials: P
authors.lastname: Vattanaviboon
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand; Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand; Center of Excellence on Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand; Center of Excellence on Environmental Health and Toxicology (EHT), Ministry Of Education, Bangkok, Thailand.
authors.forename: Skorn
authors.initials: S
authors.lastname: Mongkolsuk
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology; D005287:Ferredoxin-NADP Reductase / Q000737:chemistry / Q000235:genetics*; D020869:Gene Expression Profiling; D007506:Iron-Sulfur Proteins / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D007506:Iron-Sulfur Proteins; D005287:Ferredoxin-NADP Reductase