Chlorella viruses encode most, if not all, of the machinery to glycosylate their glycoproteins independent of the endoplasmic reticulum and Golgi

Abstract

In contrast to all other viruses that use the host machinery located in the endoplasmic reticulum and Golgi to glycosylate their glycoproteins, the large dsDNA-containing chlorella viruses encode most, if not all, of the components to glycosylate their major capsid proteins. Furthermore, all experimental results indicate that glycosylation occurs independent of the endoplasmic reticulum and Golgi.

Identification of an l -Rhamnose Synthetic Pathway in Two Nucleocytoplasmic Large DNA Viruses

“…Thus, mimivirus may also encode some, if not all, of its glycosylation machinery. Studies on the enzymes involved in glycoconjugate production encoded by NCLDVs could provide important insights, not only about their role in viral life cycles but also about the predicted long evolutionary history of these viruses, including relationships with bacterial glycans and the evolution of the eukaryotic glycosylation machinery (42). L-Rhamnose is common in plants, where it is an important component of surface polysaccharides as well as small molecules.…”

“…For example, several lines of evidence indicate that Paramecium bursaria chlorella virus 1 (PBCV-1) and other chlorovirus members, such as Acanthocystis turfacea chlorella virus 1 (ATCV-1), encode at least part, if not all, of the machinery required to glycosylate their structural proteins, including glycosyltransferases (13,21,30,33,(41)(42)(43). Furthermore, glycosylation occurs independently of the host endoplasmic reticulum (ER)-Golgi system (33,(42)(43)(44). The PBCV-1 major capsid protein located on the viral surface is glycosylated, and the glycan moieties contribute to virus protease resistance and antigenicity.…”

Archaeal virus with exceptional virion architecture and the largest single-stranded DNA genome

“…Such additional functions may modulate virushost interactions and increase ACV's chances in the arms race with its host. For example, the three carbohydrate metabolism enzymes encoded by ACV, as in the case of algae-infecting phycodnaviruses (35), might be involved in the glycosylation of viral and/or cellular proteins. Such modification would explain the inability to determine the identity of the major capsid proteins by MALDI-TOF analysis.…”

Crystal Structure of a Virus-Encoded Putative Glycosyltransferase

“…Glycosylation of the PBCV-1 major capsid protein, Vp54, is at least partially performed by the viral glycosyltransferases (11,20,33,38,41). PBCV-1 encodes 5 putative glycosyltransferases.…”