Chapter 8
Ultra-Performance Liquid Chromatography/Mass
Spectrometry for the Detection and Quantification of
Diffusible Signal Factor (DSF) Family Quorum-Sensing
Signals
Lian Zhou, Shuang Sun, Wei Zhang, and Ya-Wen He
Abstract
Molecules of the diffusible signal factor (DSF) family represent a class of widely conserved quorum-sensing
signals used by many Gram-negative bacterial pathogens. The measurement of DSF family signals is
essential for understanding their biological roles, signaling pathway, and regulatory network. We are
presenting here methods for extraction and purification of DSF family signals from culture supernatants,
and further quantification of members of DSF family signals using an ultra-performance liquid chro-
matographic system (UPLC) coupled with an accurate time-of-flight mass spectrometry (TOF-MS)
analysis.
Key wordsQuorum sensing, Diffusible signal factor, Xanthomonas, Quantification, Ultra-
performance liquid chromatographic system, Mass spectrometry1 Introduction
The diffusible signaling factor (DSF)-based quorum-sensing (QS)
system, which was initially identified in the plant bacterial pathogen
Xanthomonas campestrispv.campestris (Xcc), has emerged as a
widely conserved cell-cell communication mechanism in diverse
Gram-negative bacteria, such asXylella fastidiosa,Lysobacter enzy-
mogenes,Stenotrophomonas maltophilia,Burkholderia cepacia, and
Pseudomonas aeruginosa[1, 2]. Typically, the DSF family signals are
cis-2-unsaturated fatty acids (Fig. 1), which regulate diverse
biological functions such as bacterial virulence, biofilm formation,
antibiotic resistance, adaptation, and fitness. DSF activity was first
detected based on its ability to restore endoglucanase production in
aXcc rpfFmutant [3]. The detection system was further improved
by fusing the promoter of an endoglucanase gene to the GUS
(β-glucuronidase) reporter gene [4, 5]. By using this improvedLivia Leoni and Giordano Rampioni (eds.),Quorum Sensing: Methods and Protocols, Methods in Molecular Biology,
vol. 1673,https://doi.org/10.1007/978-1-4939-7309-5_8,©Springer Science+Business Media LLC 2018
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