Identification of AlgR-regulated genes in Pseudomonas aeruginosa by use of microarray analysis.
The Pseudomonas aeruginosa transcriptional regulator AlgR controls a variety of different processes, including alginate production, type IV pilus function, and virulence, indicating that AlgR plays a pivotal role in the regulation of gene expression. In order to characterize the AlgR regulon, Pseudomonas Affymetrix GeneChips were used to generate the transcriptional profiles of (i) P. aeruginosa PAO1 versus its algR mutant in mid-logarithmic phase, (ii) P. aeruginosa PAO1 versus its algR mutant in stationary growth phase, and (iii) PAO1 versus PAO1 harboring an algR overexpression plasmid. Expression analysis revealed that, during mid-logarithmic growth, AlgR activated the expression of 58 genes while it repressed the expression of 37 others, while during stationary phase, it activated expression of 45 genes and repression of 14 genes. Confirmatory experiments were performed on two genes found to be AlgR repressed (hcnA and PA1557) and one AlgR-activated operon (fimU-pilVWXY1Y2). An S1 nuclease protection assay demonstrated that AlgR repressed both known hcnA promoters in PAO1. Additionally, direct measurement of hydrogen cyanide (HCN) production showed that P. aeruginosa PAO1 produced threefold-less HCN than did its algR deletion strain. AlgR also repressed transcription of two promoters of the uncharacterized open reading frame PA1557. Further, the twitching motility defect of an algR mutant was complemented by the fimTU-pilVWXY1Y2E operon, thus identifying the AlgR-controlled genes responsible for this defect in an algR mutant. This study identified four new roles for AlgR: (i) AlgR can repress gene transcription, (ii) AlgR activates the fimTU-pilVWXY1Y2E operon, (iii) AlgR regulates HCN production, and (iv) AlgR controls transcription of the putative cbb3-type cytochrome PA1557.
Department of Microbiology and Immunology, Program in Molecular Pathogenesis and Immunity, Louisiana Center for Lung Biology and Immunotherapy, Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112-2699, USA.
Stephen E
SE
Lizewski
Jill R
JR
Schurr
Debra W
DW
Jackson
Anders
A
Frisk
Alexander J
AJ
Carterson
Michael J
MJ
Schurr
D000222:Adaptation, Physiological / Q000235:genetics / Q000502:physiology; D000464:Alginates; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D020723:Glucuronic Acid / Q000096:biosynthesis / Q000235:genetics; D006603:Hexuronic Acids; D009068:Movement / Q000502:physiology; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D009876:Operon / Q000235:genetics / Q000502:physiology; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D050891:Oxidoreductases Acting on CH-NH2 Group Donors; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D018085:Regulon; D015398:Signal Transduction; D015719:Single-Strand Specific DNA and RNA Endonucleases / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014774:Virulence / Q000235:genetics
C110681:AlgR protein, Pseudomonas aeruginosa; D000464:Alginates; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D006603:Hexuronic Acids; D009097:Multienzyme Complexes; D015534:Trans-Activators; D020723:Glucuronic Acid; D010088:Oxidoreductases; D050891:Oxidoreductases Acting on CH-NH2 Group Donors; C112800:glycine dehydrogenase (cyanide-forming); C414443:cbb3 oxidase; D003576:Electron Transport Complex IV; D015719:Single-Strand Specific DNA and RNA Endonucleases