title: Bacteriophage tailspike proteins as molecular probes for sensitive and selective bacterial detection.
abstract: We report the use of genetically engineered tailspike proteins (TSPs) from the P22 bacteriophage for the sensitive and selective detection of Salmonella enterica serovar Typhimurium. High yields of two mutant TSPs, one with an N-terminal cysteine (N-Cys) and another with a C-terminal cysteine (C-Cys), have been obtained using recombinant protein expression and purification in Escherichia coli. The mutant TSPs did not have the native endorhamnosidase enzymatic activity of intact P22 phage as well as wild type TSPs (wtTSPs). We have used the Cys-tag to immobilize these TSPs onto gold coated surfaces using thiol-chemistry. Our results demonstrate that the N-Cys configuration of TSPs gives a bacterial capture density of 25.87 ± 0.61 bacteria/100 μm(2) while the C-Cys configuration shows a density of 8.57 ± 0.19 bacteria/100 μm(2). This confirms that the appropriate orientation of the TSPs on the surface is important for efficient capture of the host bacteria. The bacterial capture density of the mutant N-Cys TSP was also 6-fold better than that obtained for intact P22 phage as well as wtTSPs. Bovine-serum albumin was used as a protective layer to prevent any non-specific binding of the bacteria onto the gold substrate. The recognition specificity was confirmed using 3 strains of E. coli which showed negligible binding. In addition, the host bacteria did not show any binding in the absence of the TSPs on the surface. We further show a selective real-time analytical detection of Salmonella by N-Cys mTSP-immobilized on gold coated SF-10 glass plates using surface plasmon resonance. The sensitivity of detection was found to be 10(3)cfu/ml of bacteria.
authors.affiliation: Department of Electrical and Computer Engineering, National Institute for Nanotechnology, University of Alberta, Edmonton, Canada.
authors.forename: Amit
authors.initials: A
authors.lastname: Singh
authors.forename: Sunil K
authors.initials: SK
authors.lastname: Arya
authors.forename: Nick
authors.initials: N
authors.lastname: Glass
authors.forename: Pejman
authors.initials: P
authors.lastname: Hanifi-Moghaddam
authors.forename: Ravendra
authors.initials: R
authors.lastname: Naidoo
authors.forename: Christine M
authors.initials: CM
authors.lastname: Szymanski
authors.forename: Jamshid
authors.initials: J
authors.lastname: Tanha
authors.forename: Stephane
authors.initials: S
authors.lastname: Evoy
mesh_terms: D058491:Bacterial Load / Q000295:instrumentation*; D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006026:Glycoside Hydrolases; D015336:Molecular Probe Techniques / Q000295:instrumentation*; D019779:Salmonella enterica / Q000302:isolation & purification* / Q000378:metabolism; D012680:Sensitivity and Specificity; D020349:Surface Plasmon Resonance / Q000295:instrumentation*; D017376:Viral Tail Proteins / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D017376:Viral Tail Proteins; D006026:Glycoside Hydrolases; C083268:tailspike protein, bacteriophage