title: Pseudomonas aeruginosa produces an extracellular deoxyribonuclease that is required for utilization of DNA as a nutrient source.
abstract: Pseudomonas aeruginosa is an opportunistic pathogen that occupies a wide variety of environmental niches. Extracellular DNA is ubiquitous in various environments and is a rich source of carbon, nitrogen and phosphate. Here we show that P. aeruginosa is capable of using DNA as a nutrient source. Under phosphate-limiting conditions, or when DNA is supplied as a source of phosphate, expression of PA3909 is induced. PA3909 encodes an extracellular deoxyribonuclease (DNase), which is required for degradation of DNA and utilization of DNA as a source of carbon, nitrogen and phosphate. Stabilization of PA3909 by the addition of excess Mg(2+) and Ca(2+) was required for DNase activity in culture supernatants. Extracellular DNase activity was seen in multiple P. aeruginosa strains and isolates from cystic fibrosis patients. The primary Xcp type II secretion system but not the Hxc type II secretion system is required for DNase activity and the ability to use DNA as a source of nutrients. This study identifies an extracellular DNase produced by P. aeruginosa that enables degradation of extracellular DNA into an accessible source of carbon, nitrogen and phosphate. DNase production by P. aeruginosa also has important implications for virulence and biofilm formation.
authors.affiliation: Department of Microbiology and Infectious Diseases, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada.
authors.forename: Heidi
authors.initials: H
authors.lastname: Mulcahy
authors.forename: Laetitia
authors.initials: L
authors.lastname: Charron-Mazenod
authors.forename: Shawn
authors.initials: S
authors.lastname: Lewenza
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000235:genetics / Q000378:metabolism*; D005089:Exocytosis / Q000502:physiology; D016680:Genome, Bacterial; D008274:Magnesium / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000201:enzymology / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D010710:Phosphates; D004247:DNA; D003851:Deoxyribonucleases; D008274:Magnesium; D002118:Calcium