Construction of a mini-Tn5-luxCDABE mutant library in Pseudomonas aeruginosa PAO1: a tool for identifying differentially regulated genes.
Pseudomonas aeruginosa is a major cause of nosocomial (hospital-derived) infections, is the predominant pathogen in chronic cystic fibrosis lung infections, and remains difficult to treat due to its high intrinsic antibiotic resistance. The completion of the P. aeruginosa PAO1 genome sequence provides the opportunity for genome-wide studies to increase our understanding of the pathogenesis and biology of this important pathogen. In this report, we describe the construction of a mini-Tn5-luxCDABE mutant library and a high-throughput inverse PCR method to amplify DNA flanking the site of insertion for sequencing and insertion site mapping. In addition to producing polar knockout mutations in nonessential genes, the promoterless luxCDABE reporter present in the transposon serves as a real-time reporter of gene expression for the inactivated gene. A total of 2519 transposon insertion sites were mapped, 77% of which were nonredundant insertions. Of the insertions within an ORF, -55% of total and unique insertion sites were transcriptional luxCDABE fusions. A bias toward low insertion-site density in the genome region that surrounds the predicted terminus of replication was observed. To demonstrate the utility of chromosomal lux fusions, we performed extensive regulatory screens to identify genes that were differentially regulated under magnesium or phosphate limitation. This approach led to the discovery of many known and novel genes necessary for these environmental adaptations, including genes involved in resistance to cationic antimicrobial peptides. This dual-purpose mutant library allows for functional and regulation studies and will serve as a resource for the research community to further our understanding of P. aeruginosa biology.
Lewenza
Shawn
S
Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.
Falsafi
Reza K
RK
Winsor
Geoff
G
Gooderham
W James
WJ
McPhee
Joseph B
JB
Brinkman
Fiona S L
FS
Hancock
Robert E W
RE
D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D004269:DNA, Bacterial; D004352:Drug Resistance, Microbial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D015723:Gene Library; D017930:Genes, Reporter; D016680:Genome, Bacterial; D008274:Magnesium / Q000494:pharmacology; D016254:Mutagenesis, Insertional; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D011552:Pseudomonas Infections / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015183:Restriction Mapping
D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011993:Recombinant Fusion Proteins; D008274:Magnesium