Peptide-Based Fluorescence Resonance Energy Transfer Protease Substrates for the Detection and Diagnosis of Bacillus Species

Department of Medical Microbiology and Infectious Diseases, Erasmus MC, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands.
Analytical Chemistry (Impact Factor: 5.64). 03/2011; 83(7):2511-7. DOI: 10.1021/ac102764v
Source: PubMed


We describe the development of a highly specific enzyme-based fluorescence resonance energy transfer (FRET) assay for easy and rapid detection both in vitro and in vivo of Bacillus spp., among which are the members of the B. cereus group. Synthetic substrates for B. anthracis proteases were designed and exposed to secreted enzymes of a broad spectrum of bacterial species. The rational design of the substrates was based on the fact that the presence of D-amino acids in the target is highly specific for bacterial proteases. The designed D-amino acids containing substrates appeared to be specific for B. anthracis but also for several other Bacillus spp. and for both vegetative cells and spores. With the use of mass spectrometry (MS), cleavage products of the substrates could be detected in sera of B. anthracis infected mice but not in healthy mice. Due to the presence of mirrored amino acids present in the substrate, the substrates showed high species specificity, and enzyme isolation and purification was redundant. The substrate wherein the D-amino acid was replaced by its L-isomer showed a loss of specificity. In conclusion, with the use of these substrates a rapid tool for detection of B. anthracis spores and diagnosis of anthrax infection is at hand. We are the first who present fluorogenic substrates for detection of bacterial proteolytic enzymes that can be directly applied in situ by the use of D-oriented amino acids.

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    • "showed very active proteolytic activity against several of the LL, LD, and DD substrates. Furthermore, the D-amino acid substrates containing k-k, l-l, and r-r were cleaved by proteases from Bacillus spp., in agreement with previous data [14]. P. gingivalis culture supernatant showed a relative broad proteolytic activity on the LD-amino-acid-containing substrates, with 12% of the D-amino acid substrates being cleaved. "
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    • "The use of reporter molecules for which the mass changes when in contact with microbial virulence factors has been described to help assess the putative invasive potential of bacterial species. Signal peptides that are specifically cut by known proteases have shown diagnostic value for the identification of anthrax and periodontitis [49, 50]. "
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