Dominant role of paraoxonases in inactivation of the Pseudomonas aeruginosa quorum-sensing signal N-(3-oxododecanoyl)-L-homoserine lactone

John F. Teiber, Sven Horke, Donovan C. Haines, Puneet K. Chowdhary, Junhui Xiao, Gerald L. Kramer, Robert W. Haley, Dragomir I. Draganov

Research output: Contribution to journalArticle

94 Scopus citations

Abstract

The pathogenic bacterium Pseudomonas aeruginosa causes serious infections in immunocompromised patients. N-(3-Oxododecanoyl)-L-homoserine lactone (3OC12-HSL) is a key component of P. aeruginosa's quorum-sensing system and regulates the expression of many virulence factors. 3OC12-HSL was previously shown to be hydrolytically inactivated by the paraoxonase (PON) family of calcium-dependent esterases, consisting of PON1, PON2, and PON3. Here we determined the specific activities of purified human PONs for 3OC12-HSL hydrolysis, including the common PON1 polymorphic forms, and found they were in the following order: PON2≫PON1192R>PON1192Q> PON3. PON2 exhibited a high specific activity of 7.6 ± 0.4 μmols/min/mg at 10 μM3OC12-HSL, making it the best PON2 substrate identified to date. By use of class-specific inhibitors, approximately 85 and 95% of the 3OC12-HSL lactonase activity were attributable to PON1 in mouse and human sera, respectively. In mouse liver homogenates, the activity was metal dependent, with magnesium- and manganese-dependent lactonase activities comprising 10 to 15% of the calcium-dependent activity. In mouse lung homogenates, all of the activity was calcium dependent. The calcium-dependent activities were irreversibly inhibited by extended EDTA treatment, implicating PONs as the major enzymes inactivating 3OC12-HSL. In human HepG2 and EA.hy 926 cell lysates, the 3OC12-HSL lactonase activity closely paralleled the PON2 protein levels after PON2 knockdown by small interfering RNA treatment of the cells. These findings suggest that PONs, particularly PON2, could be an important mechanism by which 3OC12-HSL is inactivated in mammals.

Original languageEnglish (US)
Pages (from-to)2512-2519
Number of pages8
JournalInfection and immunity
Volume76
Issue number6
DOIs
StatePublished - Jun 1 2008

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases

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