John C. Samuelson, M.D., Ph.D.

Professor of Molecular and Cell Biology, BUGSDM
Professor of Microbiology
72 East Concord Street
Office: E425; 617-414-1054
Lab: E408; 617-414-1098

B.A. Swarthmore College
M.D.-Ph.D. Harvard Medical School

Our lab studies the glycobiology of protozoan parasites that cause diarrhea (Cryptosporidium and Giardia), dysentery (Entamoeba), birth defects (Toxoplasma), and blindness (Acanthamoeba). In particular, we use mass spectrometric, biochemical, and genetic methods to characterize sugars added to glycoproteins, as well as the enzymes that make or remove these sugars (glycosyltransferases and glycohydrolases, respectively) (reviewed in ref. 1 and ref. 2). These sugars may be new targets for anti-microbial reagents (ref. 3). Of recent interest here are Toxoplasma enzymes that add O-linked fucose to proteins, which form assemblies (fucosomes) in close association with the nuclear pore complex (ref. 4). The protein composition of the fucosomes suggests this novel structure is involved in transcription, mRNA processing, and transport of proteins and mRNA into and out of the nucleus. Assemblies of O-fucosylated proteins are also present in Cryptosporidium and Acanthamoeba, although their appearance and composition is likely distinct from that of Toxoplasma.

We also study sugar polymers and glycoproteins present in cyst and oocyst walls of these parasites, which are critical for their transmission from person to person (reviewed in 5 and refs. 6 to 8). The simple model we have developed is that these walls contain sugar polymers similar to those in fungal and plant walls: chitin (Entamoeba), glucan (Toxoplasma), and cellulose (Acanthamoeba). In contrast to fungi and plants, glycoproteins in the parasite walls are few and are for the most part lectins (proteins that bind sugars), which bind chitin, glucan, or cellulose. These wall lectins are unique to each parasite and may be targets for diagnostic reagents. Finally, we have explored the potential use of alcohol-based hand sanitizers to prevent transmission of Giardia, Entamoeba, and Acanthamoeba (refs. 9, 10).

Representative Publications

  1. Samuelson J, Robbins PW. 2014. Effects of N-glycan precursor length diversity on quality control of protein folding and on protein glycosylation. Semin Cell Dev Biol 41:121-128. PMID: 25475176
  2. Haserick JR, Leon D, Samuelson J, Costello CE. 2017. N-glycans of Cryptosporidium parvum contain a single mannose arm, are barely processed in the ER or Golgi, and show a strong bias for sites with threonine. Mol Cell Proteomics 16:S42-S53. PMID: 28179475
  3. Chatterjee A, Ratner DM, Ryan CM, Johnson PJ, O’Keefe BR, Secor WE, Anderson DJ, Robbins PW, Samuelson J. 2015. Anti-Retroviral Lectins Have Modest Effects on Adherence of Trichomonas vaginalis to Epithelial Cells In Vitro and on Recovery of Tritrichomonas foetus in a Mouse Vaginal Model. PLoS One 10:e0135340. PMID: 26252012
  4. Bandini G, Haserick JR, Motari E, Ouologuem DT, Lourido S, Roos DS, Costello CE, Robbins PW, Samuelson J. 2016. O-fucosylated glycoproteins form assemblies in close proximity to the nuclear pore complexes of Toxoplasma gondii. Proc Natl Acad Sci USA 113:11567-11572. PMID: 27663739
  5. Samuelson J, Bushkin GG, Chatterjee A, Robbins PW. 2013. Strategies to discover the structural components of cyst and oocyst walls. Eukaryot Cell 12:1578-1587. PMID: 24096907
  6. Chatterjee A, Carpentieri A, Ratner DM, Bullitt E, Costello CE, Robbins PW, Samuelson J. 2010. Giardia cyst wall protein 1 is a lectin that binds curled fibrils of the GalNAc homopolymer. PLoS Pathogens 6: e1001059. PMID: 20808847
  7. Bushkin GG, Motari E, Carpentieri A, Dubey JP, Costello CE, Robbins PW, Samuelson J. 2013. Evidence for a structural role for acid-fast lipids in oocyst walls of Cryptosporidium, Toxoplasma, and Eimeria. MBio 4:e00387-13. PMID: 24003177
  8. Bushkin GG, Motari E, Magnelli P, Gubbels MJ, Dubey JP, Miska KB, Bullitt E, Costello CE, Robbins PW, Samuelson J. 2012. β-1,3-glucan, which can be targeted by drugs, forms a trabecular scaffold in the oocyst walls of Toxoplasma and Eimeria. MBio 3:e00258-12. PMID: 23015739
  9. Chatterjee A, Bandini G, Motari E, Samuelson J. 2015. Ethanol and isopropanol in concentrations present in hand sanitizers sharply reduce excystation of Giardia and Entamoeba and eliminate oral infectivity of Giardia cysts in gerbils. Antimicrob Agents Chemother 59:6749-6754. PMID: 26282413
  10. Aqeel Y, Rodriguez R Chatterjee A, Ingalls RR, Samuelson J. 2017. Killing of diverse eye pathogens (Acanthamoeba castellanii, Fusarium solani, and Chlamydia trachomatis) with alcohols. PLoS Negl Trop Dis 11:e0005382 PMID: 2818267

Complete bibliography located at: =ascending.