Paramecium bursaria Chlorella virus 1 encodes two enzymes involved in the biosynthesis of GDP-L-fucose and GDP-D-rhamnose.

Abstract

At least three structural proteins in Paramecium bursaria Chlorella virus (PBCV-1) are glycosylated, including the major capsid protein Vp54. However, unlike other glycoprotein-containing viruses that use host-encoded enzymes in the endoplasmic reticulum-Golgi to glycosylate their proteins, PBCV-1 encodes at least many, if not all, of the glycosyltransferases used to glycosylate its structural proteins. As described here, PBCV-1 also encodes two open reading frames that resemble bacterial and mammalian enzymes involved in de novo GDP-L-fucose biosynthesis. This pathway, starting from GDP-D-mannose, consists of two sequential steps catalyzed by GDP-D-mannose 4,6 dehydratase (GMD) and GDP-4-keto-6-deoxy-D-mannose epimerase/reductase, respectively. The two PBCV-1-encoded genes were expressed in Escherichia coli, and the recombinant proteins had the predicted enzyme activity. However, in addition to the dehydratase activity, PBCV-1 GMD also had a reductase activity, producing GDP-D-rhamnose. In vivo studies established that PBCV-1 GMD and GDP-4-keto-6-deoxy-D-mannose epimerase/reductase are expressed after virus infection and that both GDP-L-fucose and GDP-D-rhamnose are produced in virus-infected cells. Thus, PBCV-1 is the first virus known to encode enzymes involved in nucleotide sugar metabolism. Because fucose and rhamnose are components of the glycans attached to Vp54, the pathway could circumvent a limited supply of GDP sugars by the algal host.

• Authors: Michela Tonetti, Davide Zanardi, James R Gurnon, Floriana Fruscione, Andrea Armirotti, Gianluca Damonte, Laura Sturla, Antonio De Flora, James L Van Etten
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 278 Issue 24 Pg. 21559-65 (Jun 13 2003) ISSN: 0021-9258 [Print] United States
• PMID: 12679342 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Anions
• GDP-rhamnose
• Guanosine Diphosphate Sugars
• Monosaccharides
• Recombinant Proteins
• Guanosine Diphosphate Fucose

Topics

• Animals
• Anions
• Blotting, Northern
• Chlorella (genetics, metabolism)
• Chromatography, High Pressure Liquid
• Chromatography, Ion Exchange
• Electrophoresis, Polyacrylamide Gel
• Escherichia coli (metabolism)
• Gas Chromatography-Mass Spectrometry
• Genome, Viral
• Guanosine Diphosphate Fucose (biosynthesis)
• Guanosine Diphosphate Sugars (biosynthesis)
• Kinetics
• Models, Chemical
• Molecular Sequence Data
• Monosaccharides (chemistry)
• Open Reading Frames
• Paramecium (virology)
• Recombinant Proteins (chemistry)
• Spectrometry, Mass, Electrospray Ionization
• Time Factors