Posttranslational N-glycosylation of the hepatitis B virus large envelope protein.
BACKGROUND
The addition of N-linked glycans to proteins is normally a cotranslational process that occurs during translocation of the nascent protein to the endoplasmic reticulum. Here, we report on an exception to this rule occurring on the hepatitis B virus (HBV) large L envelope protein that is a subject to co-plus posttranslational N-glycosylation.


RESULTS
By using an improved detection system, we identified so far unrecognized, novel isoforms of L. Based on mutational analyses, the use of N-glycosylation inhibitors, and pulse-chase studies, we showed that these isoforms are due to posttranslational N-glycan addition to the asparagines 4 and 112 within the preS domain of L. While an inhibition of N-glycosylation and glycan trimming profoundly blocked virus assembly and release, the posttranslational N-glycosylation of L itself was found to be dispensable for HBV morphogenesis.


CONCLUSIONS
These data together with previous results implicate that the N-glycosylation requirements of virion release are due to functional inhibition of cell glycoproteins engaged by HBV.
Lambert
Carsten
C
Institute for Medical Microbiology and Hygiene, University of Mainz, Augustusplatz, Mainz, Germany. lambert@uni-mainz.de
Prange
Reinhild
R
D002460:Cell Line; D004847:Epithelial Cells / Q000821:virology; D015967:Gene Expression Regulation, Viral; D006031:Glycosylation; D006515:Hepatitis B virus / Q000378:metabolism*; D006801:Humans; D020033:Protein Isoforms; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
C096362:L protein, hepatitis B virus; D020033:Protein Isoforms; D014759:Viral Envelope Proteins