1. Quantitative analysis of autoinducing peptide I (AIP-I) from Staphylococcus aureus cultures using ultrahigh performance liquid chromatography-high resolving power mass spectrometry
Hiyas A Junio, Daniel A Todd, Keivan A Ettefagh, Brandie M Ehrmann, Jeffrey S Kavanaugh, Alexander R Horswill, Nadja B Cech J Chromatogr B Analyt Technol Biomed Life Sci. 2013 Jul 1;930:7-12. doi: 10.1016/j.jchromb.2013.04.019. Epub 2013 Apr 19.
Staphylococcus aureus infections acquired in hospitals now cause more deaths per annum in the US than does HIV/AIDS. Perhaps even more alarming is the rise in community associated methicillin-resistant S. aureus (CA-MRSA) infections, which have spread out of hospital settings and are infecting otherwise healthy individuals. The mechanism of enhanced pathogenesis in CA-MRSA remains unclear, but it has been postulated that high activity in the agr quorum-sensing system could be a contributing factor. The purpose of this study was to develop a quantitative method for analysis of autoinducing peptide I (AIP-I), the activating signal for the agr system in S. aureus. An effective method was developed using ultrahigh performance liquid chromatography (UHPLC) coupled to electrospray ionization mass spectrometry with an LTQ Orbitrap mass spectrometer. Relying on the exceptional resolving power and mass accuracy of this instrument configuration, it was possible to quantify AIP-I directly from the complex growth media of S. aureus cultures with a limit of detection (LOD) of 0.25μM and a linear dynamic range of 2.6 to 63μM. The method was then employed to monitor time-dependent production of AIP-I by S. aureus cultures, and it was observed that AIP-I production reached a maximum and leveled off after approximately 16h. Finally, it was determined that virulence of S. aureus was correlated with AIP-I production in some (but not all) strains analyzed.
2. Reprogramming Probiotic Lactobacillus reuteri as a Biosensor for Staphylococcus aureus Derived AIP-I Detection
David Lubkowicz, Chun Loong Ho, In Young Hwang, Wen Shan Yew, Yung Seng Lee, Matthew Wook Chang ACS Synth Biol. 2018 May 18;7(5):1229-1237. doi: 10.1021/acssynbio.8b00063. Epub 2018 Apr 13.
Gram-positive Staphylococcus aureus infection that results in pneumonia, urinary tract infection, and in severe cases, sepsis, has recently been classified as a serious threat to public health. Rapid and cost-effective detection of these infections are costly and time-consuming. Here, we present probiotic lactic acid bacteria engineered to detect autoinducer peptide-I (AIP-I), a quorum sensing molecule produced by Staphylococcus sp. during pathogenesis. We achieved this by adapting the well-characterized agr quorum sensing ( agrQS) from Staphylococcus aureus into Lactobacillus reuteri. The engineered biosensor is able to detect AIP-I levels in the nanomolar to micromolar range. We further investigated the function of the biosensor to detect real-time changes in AIP-I levels to understand the dynamics of Staphylococcus aureus under various strenuous conditions. The developed sensors would be useful for detection of Staphylococcus contamination in hospital settings and for high-throughput drug screening.
3. Design and synthesis of macrocyclic peptomers as mimics of a quorum sensing signal from Staphylococcus aureus
Sarah A Fowler, Danielle M Stacy, Helen E Blackwell Org Lett. 2008 Jun 19;10(12):2329-32. doi: 10.1021/ol800908h. Epub 2008 May 14.
We report the design and synthesis of macrocyclic peptide-peptoid hybrids (peptomers) as analogs of autoinducing peptide I (AIP-I) from Staphylococcus aureus. Our solid-phase synthetic route includes efficient microwave-assisted reactions and a tandem macrocyclization-cleavage step, and we demonstrate its compatibility with parallel synthesis through the generation of a focused peptomer library. One of the peptomers was capable of stimulating biofilm formation in S. aureus, a phenotype linked to AIP-I receptor (AgrC-I) inhibition.
