Interactions between hepatitis delta virus proteins.
The 195- and 214-amino-acid (aa) forms of the delta protein (deltaAg-S and deltaAg-L, respectively) of hepatitis delta virus (HDV) differ only in the 19-aa C-terminal extension unique to deltaAg-L. deltaAg-S is needed for genome replication, while deltaAg-L is needed for particle assembly. These proteins share a region at aa 12 to 60, which mediates protein-protein interactions essential for HDV replication. H. Zuccola et al. (Structure 6:821-830, 1998) reported a crystal structure for a peptide spanning this region which demonstrates an antiparallel coiled-coil dimer interaction with the potential to form tetramers of dimers. Our studies tested whether predictions based on this structure could be extrapolated to conditions where the peptide was replaced by full-length deltaAg-S or deltaAg-L, and when the assays were not in vitro but in vivo. Nine amino acids that are conserved between several isolates of HDV and predicted to be important in multimerization were mutated to alanine on both deltaAg-S and deltaAg-L. We found that the predicted hierarchy of importance of these nine mutations correlated to a significant extent with the observed in vivo effects on the ability of these proteins to (i) support in trans the replication of the HDV genome when expressed on deltaAg-S and (ii) act as dominant-negative inhibitors of replication when expressed on deltaAg-L. We thus infer that these biological activities of deltaAg depend on ordered protein-protein interactions.
Moraleda
G
G
Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111-2497, USA.
Dingle
K
K
Biswas
P
P
Chang
J
J
Zuccola
H
H
Hogle
J
J
Taylor
J
J
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D002846:Chromatography, Affinity; D017124:Conserved Sequence / Q000235:genetics; D019281:Dimerization; D005799:Genes, Dominant / Q000235:genetics; D005814:Genes, Viral / Q000235:genetics; D018963:Hepatitis Antigens / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D003698:Hepatitis Delta Virus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D035923:Hepatitis delta Antigens; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D012313:RNA / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D000079962:RNA, Circular; D012367:RNA, Viral / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion / Q000235:genetics; D013816:Thermodynamics; D014407:Tumor Cells, Cultured; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019065:Virus Assembly; D014779:Virus Replication
D018963:Hepatitis Antigens; D035923:Hepatitis delta Antigens; D010446:Peptide Fragments; D000079962:RNA, Circular; D012367:RNA, Viral; D011993:Recombinant Fusion Proteins; D014764:Viral Proteins; C442244:hepatitis delta virus large antigen; D012313:RNA