4tqg

Publication Abstract from PubMed

Giant viruses mimicking microbes, by the sizes of their particles and the heavily glycosylated fibrils surrounding their capsids, infect Acanthamoeba sp, which are ubiquitous unicellular eukaryotes. The glycans on fibrils are produced by virally encoded enzymes, organized in gene clusters. As Mimivirus, Megavirus particles are mainly composed of virally synthesized GlcNac. They also contain RhaNAc, a rare sugar; the enzymes involved in its synthesis are encoded by a gene cluster specific to Megavirus close relatives. We combined activity assays on two enzymes of the pathway with mass spectrometry and NMR studies to characterize their specificities. Mg534 is a 4,6-dehydratase 5-epimerases, its 3D structure suggests it belongs to a third subfamily of inverting dehydratases; Mg535, next in the pathway, is a bifunctional 3-epimerase 4-reductase. This study is another example that giant viruses perform their glycan synthesis using enzymes different from their cellular counterparts, raising again the question on the origin of these pathways.

Giant virus Megavirus chilensis encodes the biosynthetic pathway for uncommon acetamido sugars.,Piacente F, De Castro C, Jeudy S, Molinaro A, Salis A, Damonte G, Bernardi C, Abergel C, Tonetti M J Biol Chem. 2014 Jul 17. pii: jbc.M114.588947. PMID:25035429^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.