Eric Arthur Johnson

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How the widely used botulinum neurotoxin A (BoNT/A) recognizes and enters neurons is poorly understood. We found that BoNT/A enters neurons by binding to the synaptic vesicle protein SV2 (isoforms A, B, and C). Fragments of SV2 that harbor the toxin interaction domain inhibited BoNT/A from binding to neurons. BoNT/A binding to SV2A and SV2B knockout(More)
Plating of the astaxanthin-producing yeast Phaffia rhodozyma onto yeast-malt agar containing 50 muM antimycin A gave rise to colonies of unusual morphology, characterized by a nonpigmented lower smooth surface that developed highly pigmented vertical papillae after 1 to 2 months. Isolation and purification of the pigmented papillae, followed by testing for(More)
Clostridium botulinum is a taxonomic designation for many diverse anaerobic spore-forming rod-shaped bacteria that have the common property of producing botulinum neurotoxins (BoNTs). The BoNTs are exoneurotoxins that can cause severe paralysis and death in humans and other animal species. A collection of 174 C. botulinum strains was examined by amplified(More)
The botulinum neurotoxins (BoNTs) are category A biothreat agents which have been the focus of intensive efforts to develop vaccines and antibody-based prophylaxis and treatment. Such approaches must take into account the extensive BoNT sequence variability; the seven BoNT serotypes differ by up to 70% at the amino acid level. Here, we have analyzed 49(More)
Carotenoids have recently received considerable interest because of their potential in delaying or preventing degenerative diseases such as arteriosclerosis, cancer, and aging. In this study we show that the active oxygen species singlet oxygen (1O2) and peroxyl radicals differently affect carotenoid composition and biosynthesis in the yeast Phaffia(More)
Microbial enzymes used in food processing are typically sold as enzyme preparations that contain not only a desired enzyme activity but also other metabolites of the production strain, as well as added materials such as preservatives and stabilizers. The added materials must be food grade and meet applicable regulatory standards. The purpose of this report(More)
IMPORTANCE Increased use of computed tomography (CT) in pediatrics raises concerns about cancer risk from exposure to ionizing radiation. OBJECTIVES To quantify trends in the use of CT in pediatrics and the associated radiation exposure and cancer risk. DESIGN Retrospective observational study. SETTING Seven US health care systems. PARTICIPANTS The(More)
Carotenoids occur universally in photosynthetic organisms but sporadically in nonphotosynthetic bacteria and eukaryotes. The primordial carotenogenic organisms were cyanobacteria and eubacteria that carried out anoxygenic photosynthesis. The phylogeny of carotenogenic organisms is evaluated to describe groups of organisms which could serve as sources of(More)
A chemically defined minimal medium for Listeria monocytogenes has been developed by modification of Welshimer's medium. The growth factors required by L. monocytogenes Scott A are leucine, isoleucine, arginine, methionine, valine, cysteine (each at 100 mg/liter), riboflavin and biotin (each at 0.5 micrograms/ml), thiamine (1.0 micrograms/ml), and thioctic(More)
Botulinum neurotoxin E (BoNT/E) can cause paralysis in humans and animals by blocking neurotransmitter release from presynaptic nerve terminals. How this toxin targets and enters neurons is not known. Here we identified two isoforms of the synaptic vesicle protein SV2, SV2A and SV2B, as the protein receptors for BoNT/E. BoNT/E failed to enter neurons(More)