title: First report of the use of a saxitoxin-protein conjugate to develop a DNA aptamer to a small molecule toxin.
abstract: Saxitoxin (STX) is a low molecular weight neurotoxin mainly produced by certain marine dinoflagellates that, along with its family of similarly related paralytic shellfish toxins, may cause the potentially fatal intoxication known as paralytic shellfish poisoning. Illness and fatality rates are low due to the effective monitoring programs that determine when toxins exceed the established regulatory action level and effectuate shellfish harvesting closures accordingly. Such monitoring programs rely on the ability to rapidly screen large volumes of samples. Many of the screening assays currently available employ antibodies or live animals. This research focused on developing an analytical recognition element that would eliminate the challenges associated with the limited availability of antibodies and the use of animals. Here we report the discovery of a DNA aptamer that targets STX. Concentration-dependent and selective binding of the aptamer to STX was determined using a surface plasmon resonance sensor. Not only does this work represent the first reported aptamer to STX, but also the first aptamer to any marine biotoxin. A novel strategy of using a toxin-protein conjugate for DNA aptamer selection was successfully implemented to overcome the challenges associated with aptamer selection to small molecules. Taking advantage of such an approach could lead to increased diversity and accessibility of aptamers to low molecular weight toxins, which could then be incorporated as analytical recognition elements in diagnostic assays for foodborne toxin detection. The selected STX aptamer sequence is provided here, making it available to any investigator for use in assay development for the detection of STX.
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5100 Paint Branch Parkway, College Park, MD 20740, USA. sara.handy@fda.hhs.gov
authors.forename: Sara M
authors.initials: SM
authors.lastname: Handy
authors.forename: Betsy Jean
authors.initials: BJ
authors.lastname: Yakes
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: DeGrasse
authors.forename: Katrina
authors.initials: K
authors.lastname: Campbell
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Elliott
authors.forename: Kelsey M
authors.initials: KM
authors.lastname: Kanyuck
authors.forename: Stacey L
authors.initials: SL
authors.lastname: Degrasse
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D001483:Base Sequence; D002138:Calibration; D017931:DNA Primers; D004277:DNA, Single-Stranded / Q000737:chemistry; D004337:Drug Carriers; D006241:Haptens / Q000737:chemistry; D006433:Hemocyanins / Q000737:chemistry; D000922:Immunotoxins / Q000737:chemistry*; D008280:Magnetics; D008969:Molecular Sequence Data; D017510:Protein Folding; D011506:Proteins / Q000737:chemistry*; D060888:Real-Time Polymerase Chain Reaction; D012530:Saxitoxin / Q000737:chemistry*; D020349:Surface Plasmon Resonance
chemical_list: D052157:Aptamers, Nucleotide; D017931:DNA Primers; D004277:DNA, Single-Stranded; D004337:Drug Carriers; D006241:Haptens; D000922:Immunotoxins; D011506:Proteins; D012530:Saxitoxin; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin