Profiling of N‐acyl‐homoserine lactones by liquid chromatography coupled with electrospray ionization and a hybrid quadrupole linear ion‐trap and Fourier‐transform ion‐cyclotron‐resonance mass spectrometry (LC‐ESI‐LTQ‐FTICR‐MS)
- 20 August 2007
- journal article
- research article
- Published by Wiley in Journal of Mass Spectrometry
- Vol. 43 (1), 82-96
- https://doi.org/10.1002/jms.1275
Abstract
A method for the comprehensive profiling of the N‐acyl‐homoserine lactone (AHL) family of bacterial quorum‐sensing molecules is presented using liquid chromatography (LC) coupled to a hybrid quadrupole linear ion trap (LTQ) and Fourier‐transform ion‐cyclotron‐resonance mass spectrometer (FTICR). We demonstrate an increase in signal intensity in MS with electrospray ionization (ESI) of the protonated molecules, [M + H]+, by using acetonitrile (ACN) instead of methanol (MeOH) as the organic solvent under the conditions in which the samples were supplied to the probe by direct infusion at constant flow rates. The presence of ACN prevents the formation of methanol adducts such as [M + MeOH + H]+ and [M + MeOH + Na]+, while also lowering the signal intensity of sodiated [M + Na]+ ions. Sensitivity of these signaling molecules in terms of signal‐to‐noise ratio (S/N) using low‐resolution LTQ‐MS and high‐resolution FTICR‐MS were compared under reversed‐phase (RP) LC separations with ESI interface. Special emphasis was paid to the choice of the separation column, its elution conditions and detection of the major AHL compounds produced by the Serratia liquefaciens strain ATCC 27592. The most promising results were obtained using a RP C16‐amide column eluted with a linear mobile phase gradient ACN/H2O containing 0.1% formic acid. The whole set of AHL homologs in bacterial extracts was detected in the extracted‐ion chromatographic (XIC) mode, and the calculations of molecular formulae were performed by including the isotopic pattern. This mode of displaying data, with a very narrow mass‐to‐charge ratio window (i.e. ± 0.0010 as m/z unit) around each selected ion, has allowed the identification of all the eight known homoserine lactones, viz. C4‐HSL, 3‐oxo‐C6‐HSL, C6‐HSL, 3‐oxo‐C8‐HSL, C8‐HSL, C10‐HSL, C12‐HSL and C14‐HSL. In addition, at least four uncommon signaling mediators previously unreported, namely, 3‐oxo‐C10:1‐HSL, 3‐oxo‐C11:2‐HSL, 3‐oxo‐C13:2‐HSL and 3‐OH‐C16‐HSL, were identified and characterized; their roles in cell‐to‐cell communication has to be elucidated. Copyright © 2007 John Wiley & Sons, Ltd.Keywords
This publication has 45 references indexed in Scilit:
- Discovery of Complex Mixtures of Novel Long‐Chain Quorum Sensing Signals in Free‐Living and Host‐Associated Marine AlphaproteobacteriaChemBioChem, 2005
- Analysis of N‐acylhomoserine lactones after alkaline hydrolysis and anion‐exchange solid‐phase extraction by capillary zone electrophoresis‐mass spectrometryElectrophoresis, 2005
- Presence of Acylated Homoserine Lactones (AHLs) and AHL-Producing Bacteria in Meat and Potential Role of AHL in Spoilage of MeatApplied and Environmental Microbiology, 2004
- Direct analysis of selected N‐acyl‐L‐homoserine lactones by gas chromatography/mass spectrometryRapid Communications in Mass Spectrometry, 2004
- Analysis of N‐acyl‐L‐homoserine lactones produced by Burkholderia cepacia with partial filling micellar electrokinetic chromatography – electrospray ionization‐ion trap mass spectrometryElectrophoresis, 2003
- Listening in on bacteria: acyl-homoserine lactone signallingNature Reviews Molecular Cell Biology, 2002
- Peer Reviewed: Scaling MS Plateaus with High-Resolution FT-ICRMSAnalytical Chemistry, 2002
- Regulation of Gene Expression by Cell-to-Cell Communication: Acyl-Homoserine Lactone Quorum SensingAnnual Review of Genetics, 2001
- Quorum Sensing in BacteriaAnnual Review of Microbiology, 2001
- Fourier transform ion cyclotron resonance mass spectrometry: A primerMass Spectrometry Reviews, 1998