N-terminal myristylation of HBV preS1 domain enhances receptor recognition.
The N-terminal portion of the large envelope protein of the human hepatitis B virus (HBV), the preS1 domain, plays a fundamental role in cell attachment and infectivity. Recent investigations have suggested that myristylation of preS1 Gly2 residue is essential for viral infectivity, but the importance of this post-translational modification on HBV-receptor interaction has not been elucidated completely. In this study we produced, using stepwise solid-phase chemical synthesis, the entire preS1[1-119] domain (adw2 subtype), and compared its receptor binding activity with the myristylated form, myristyl-preS1[2-119] in order to define the importance of fatty acid modification. Both synthetic proteins were fully characterized in terms of structural identity using TOF-MALDI mass spectrometry and analysis of tryptic fragments. Circular dichroism measurements indicated a low content of ordered structure in the preS1 protein, while the propensity of the myristylated derivative to assume a conformationally defined structure was more evident. HBV-receptor binding assays performed with plasma membranes preparations from the hepatocyte carcinoma cell line HepG2 clearly showed that the preS1[1-119] domain recognizes the HBV receptor, and confirmed that binding is occurring through the 21-47 region. The myristylated derivative recognized HBV receptor preparations with higher affinity than the preS1 domain, suggesting that the conformational transitions induced in the preS1 moiety by fatty acid post-translational modification are important for efficient attachment of viral particles to HBV receptors.
De Falco
S
S
Biopharmaceuticals, TECNOGEN S.C.p.A., Piana di Monte Verna, Italy.
Ruvo
M
M
Verdoliva
A
A
Scarallo
A
A
Raimondo
D
D
Raucci
A
A
Fassina
G
G
D000595:Amino Acid Sequence; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D004797:Enzyme-Linked Immunosorbent Assay; D006514:Hepatitis B Surface Antigens / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D019814:Myristic Acid / Q000737:chemistry*; D011498:Protein Precursors / Q000737:chemistry / Q000378:metabolism*; D011991:Receptors, Virus / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D006514:Hepatitis B Surface Antigens; D011498:Protein Precursors; D011991:Receptors, Virus; C050806:presurface protein 1, hepatitis B surface antigen; D019814:Myristic Acid