Biophysical Approaches to Solve the Structures of the Complex Glycan Shield of Chloroviruses

  • Cristina De CastroEmail author
  • Garry A. Duncan
  • Domenico Garozzo
  • Antonio Molinaro
  • Luisa Sturiale
  • Michela Tonetti
  • James L. Van Etten
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 1104)


The capsid of Paramecium bursaria chlorella virus (PBCV-1) contains a heavily glycosylated major capsid protein, Vp54. The capsid protein contains four glycans, each N-linked to Asn. The glycan structures are unusual in many aspects: (1) they are attached by a β-glucose linkage, which is rare in nature; (2) they are highly branched and consist of 8–10 neutral monosaccharides; (3) all four glycoforms contain a dimethylated rhamnose as the capping residue of the main chain, a hyper-branched fucose residue and two rhamnose residues ''with opposite absolute configurations; (4) the four glycoforms differ by the nonstoichiometric presence of two monosaccharides, l-arabinose and d-mannose; (5) the N-glycans from all of the chloroviruses have a strictly conserved core structure; and (6) these glycans do not resemble any structures previously reported in the three domains of life.

The structures of these N-glycoforms remained elusive for years because initial attempts to solve their structures used tools developed for eukaryotic-like systems, which we now know are not suitable for this noncanonical glycosylation pattern. This chapter summarizes the methods used to solve the chlorovirus complex glycan structures with the hope that these methodologies can be used by scientists facing similar problems.


Giant viruses GC-MS NMR MALDI N-glycosylation 


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Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  • Cristina De Castro
    • 1
    Email author
  • Garry A. Duncan
    • 2
  • Domenico Garozzo
    • 3
  • Antonio Molinaro
    • 4
  • Luisa Sturiale
    • 3
  • Michela Tonetti
    • 5
  • James L. Van Etten
    • 6
  1. 1.Department of Agricultural SciencesUniversity of NapoliPorticiItaly
  2. 2.Department of BiologyNebraska Wesleyan UniversityLincolnUSA
  3. 3.CNRInstitute for Polymers, Composites and BiomaterialsCataniaItaly
  4. 4.Department of Chemical SciencesUniversity of NapoliNapoliItaly
  5. 5.Department of Experimental Medicine and Center of Excellence for Biomedical ResearchUniversity of GenovaGenovaItaly
  6. 6.Department of Plant Pathology and Nebraska Center for VirologyUniversity of NebraskaLincolnUSA

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