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User:John Samuelson
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John Samuelson received his M.D. and Ph.D. in Cell and Developmental Biology from Harvard Medical School. As a post-doctoral fellow and faculty member at the Harvard School of Public Health, he discovered extensive horizontal gene transfer from bacteria and a cryptic mitochondrion-derived organelle in Entamoeba histolytica, the protist that causes dysentery and liver abscess. With his move to Boston University, Dr. Samuelson got his real introduction to glycobiology in a 15 year collaboration with Phil Robbins. Together they showed the major cyst wall proteins of Entamoeba are chitin-binding lectins and identified CBM55 at the N-terminus of the chitinase [1, 2, 3]. They showed that the most abundant cyst wall proteins of Giardia lamblia, cause of diarrhea, have Leu-rich repeats that bind to fibrils of the unique β-1,3-linked GalNAc polymer [4]. They demonstrated β-1,3-glucan in the inner layer of the oocyst wall of Toxoplasma gondii, cause of birth defects, and identified a unique glucan-binding domain at the N-terminus of the GH17 glycoside hydrolase [5]. In a separate line of experiments, Drs. Samuelson and Robbins showed that secondary loss of genes encoding Alg enzymes explains the diversity of N-glycan precursors among eukaryotes [6], demonstrated Darwinian selection for N-glycan sites in secreted proteins of the vast majority of eukaryotes that have N-glycan-dependent quality control of glycoprotein folding in the ER lumen [7], and identified N-glycans of Entamoeba, Giardia, and Plasmodium falciparum (cause of malaria) [8-10]. With Giulia Bandini they discovered a large set of nuclear proteins of Toxoplasma that are decorated with O-linked fucose [11] and with Chris West showed that the O-fucosyltransferase is a homolog of plant Spindly, which contains TPR and GT41 domains [12]. Recently, Dr. Samuelson with Breeanna Urbanowicz showed the most abundant proteins in the cyst wall of Acanthamoeba castellanii, cause of blindness, are cellulose- and chitin-binding lectins [13].
- Frisardi M, Ghosh SK, Field J, Van Dellen K, Rogers R, Robbins P, and Samuelson J. (2000). The most abundant glycoprotein of amebic cyst walls (Jacob) is a lectin with five Cys-rich, chitin-binding domains. Infect Immun. 2000;68(7):4217-24. DOI:10.1128/IAI.68.7.4217-4224.2000 |
- Van Dellen K, Ghosh SK, Robbins PW, Loftus B, and Samuelson J. (2002). Entamoeba histolytica lectins contain unique 6-Cys or 8-Cys chitin-binding domains. Infect Immun. 2002;70(6):3259-63. DOI:10.1128/IAI.70.6.3259-3263.2002 |
- Chatterjee A, Ghosh SK, Jang K, Bullitt E, Moore L, Robbins PW, and Samuelson J. (2009). Evidence for a "wattle and daub" model of the cyst wall of entamoeba. PLoS Pathog. 2009;5(7):e1000498. DOI:10.1371/journal.ppat.1000498 |