Defining the Structure and Function of Acyl-Homoserine Lactone Autoinducers
Quorum sensing plays a central role in regulating many community-derived symbiotic and pathogenic relationships of bacteria, and as such has attracted much attention in recent years. Acyl-homoserine lactones (AHLs) are important signaling molecules in the quorum sensing gene-regulatory processes found in numerous gram-negative species of bacteria that interact with eukaryotic organisms. AHLs are produced by acyl-homoserine lactone synthases. Bacteria can have multiple genes for AHL synthase enzymes, and such species are likely to produce several different types of AHLs. Determination of the types and the relative amounts of AHLs produced by AHL synthases in bacteria under varied conditions provides important insights into the mechanism of AHL synthase function and the regulation of transcriptional cascades initiated by quorum sensing signaling. This chapter describes a mass spectrometry method for determining the types and relative amounts of AHLs present in a sample.
Key wordsAcyl-homoserine lactone AHL Quorum sensing Mass spectrometry AHL synthase
The authors would like to thank Drs. Ty Gould and Robert C. Murphy for their contributions in initially developing this method, Dr. Jake Herman for help in refining the method, and Dr. Joseph Hankin, Chris Johnson, and Wesley Martin for their assistance with the mass spectrometry. We also thank Dr. Robert C. Murphy for helpful suggestions and for use of the mass spectrometry equipment, which is supported by the Lipid Maps Large Scale Collaborative Grant (NIH GM069338 to R.C.M.). This work was supported by Grants from the National Science Foundation #0703467 and #0821220.
- 1.Fuqua, C. and Eberhard, A. (1999) Signal generation in autoinduction systems: synthesis of acylated homoserine lactones by LuxI-type proteins, In G. Dunny and S.C. Winans (eds.), Cell–cell signaling in bacteria. ASM Press, Washington, DC. 211–230.Google Scholar
- 3.Churchill, M.E.A. and Herman, J.P. (2008) Acyl-homoserinelactone biosynthesis: structure and mechanism. Chapter 17, In Stephen Winans and Bonnie Bassler (eds.), Chemical communication among bacteria. ASM Press, Washington, DC.Google Scholar
- 7.Khan, S.R., Herman, J.P., Krank, K., Serkova, N.J., Churchill, M.E.A., Suga, H., and Farrand, S.K. (2007) N-(3-hydroxy-hexanoyl)-l-homoserine lactone is the biologically relevant quormone that regulates the phz operon of Pseudomonas chlororaphis (aureofaciens) Strain 30-84. Appl Environ Microbiol 73, 7443–55.PubMedCrossRefGoogle Scholar