Giant mimivirus R707 encodes a glycogenin paralogue polymerizing glucose through α- and β-glycosidic linkages

Acanthamoeba polyphaga mimivirus is a giant virus encoding 1262 genes among which many were previously thought to be exclusive to cellular life. For example, mimivirus genes encode enzymes involved in the biosynthesis of nucleotide sugars and putative glycosyltransferases. We identified in mimivirus...

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Bibliographic Details
Published in:	Biochemical journal Vol. 473; no. 20; p. 3451
Main Authors:	Rommel, Anna J, Hülsmeier, Andreas J, Jurt, Simon, Hennet, Thierry
Format:	Journal Article
Language:	English
Published:	England 15-10-2016
Subjects:	Acanthamoeba - virology Glucose - chemistry Glucose - metabolism Glucosyltransferases - chemistry Glucosyltransferases - metabolism Glycoproteins - chemistry Glycoproteins - metabolism Glycosides - chemistry Glycosides - metabolism Glycosylation Glycosyltransferases - metabolism Mimiviridae - metabolism Mimiviridae - pathogenicity Viral Proteins - chemistry Viral Proteins - metabolism glycosylation giant virus glycogen polysaccharide NMR spectroscopy
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Summary:	Acanthamoeba polyphaga mimivirus is a giant virus encoding 1262 genes among which many were previously thought to be exclusive to cellular life. For example, mimivirus genes encode enzymes involved in the biosynthesis of nucleotide sugars and putative glycosyltransferases. We identified in mimivirus a glycogenin-1 homologous gene encoded by the open reading frame R707. The R707 protein was found to be active as a polymerizing glucosyltransferase enzyme. Like glycogenin-1, R707 activity was divalent-metal-ion-dependent and relied on an intact DXD motif. In contrast with glycogenin-1, R707 was, however, not self-glucosylating. Interestingly, the product of R707 catalysis featured α1-6, β1-6 and α1-4 glycosidic linkages. Mimivirus R707 is the first reported glycosyltransferase able to catalyse the formation of both α and β linkages. Mimivirus-encoded glycans play a role in the infection of host amoebae. Co-infection of Acanthamoeba with mimivirus and amylose and chitin hydrolysate reduced the number of infected amoebae, thus supporting the importance of polysaccharide chains in the uptake of mimivirus by amoebae. The identification of a glycosyltransferase capable of forming α and β linkages underlines the peculiarity of mimivirus and enforces the concept of a host-independent glycosylation machinery in mimivirus.
ISSN:	1470-8728
DOI:	10.1042/BCJ20160280