摘要
The nucleocapsid of hepadnaviruses consisits of dimers of the core proteins. However, the mechanism of the core-core subunit interaction is not well understood. The Nterminus of the core protein of woodchuck hepatitis virus(WHV) was found containing four conserved hydrophobic amino acid residues (from residue 101 to 122 ). These residues, referred to the hydrophobic heptad repeat(hhr), distributed as heptad repeats in the primary sequence. Since hydrophobic bounds often play an important role in interaction of proteins, roles of the hhr region in capsid assembly of WHV were investigated using a cell culture system. The codons for these four hydrophobic amino acid residues and other related residues in this region were substituted with codons specifying alanine or proline. Phenotype of each of these mutants was examined at various stages of viral replication in Hub7 cells. It was found that single substitution of the four hydrophobic residues had no detectable effect, but substitution of the same residues in various paired combinations resulted in a complete inhibition of capsid assembly. The capsid assembly was inhibited when amino acid insertion occerred at the first and last two hydrophobic residues or a single amino acid deletion occurred at the first pair of hydrophobic residues. However, random amino acid substitutions in this region did not affect assembly. The results indicated that the hhr region of the core protein was necessory for capsid assembly of woodchuck hepatitis virus.
The nucleocapsid of hepadnaviruses consisits of dimers of the core proteins. However, the mechanism of the core-core subunit interaction is not well understood. The Nterminus of the core protein of woodchuck hepatitis virus(WHV) was found containing four conserved hydrophobic amino acid residues (from residue 101 to 122 ). These residues, referred to the hydrophobic heptad repeat(hhr), distributed as heptad repeats in the primary sequence. Since hydrophobic bounds often play an important role in interaction of proteins, roles of the hhr region in capsid assembly of WHV were investigated using a cell culture system. The codons for these four hydrophobic amino acid residues and other related residues in this region were substituted with codons specifying alanine or proline. Phenotype of each of these mutants was examined at various stages of viral replication in Hub7 cells. It was found that single substitution of the four hydrophobic residues had no detectable effect, but substitution of the same residues in various paired combinations resulted in a complete inhibition of capsid assembly. The capsid assembly was inhibited when amino acid insertion occerred at the first and last two hydrophobic residues or a single amino acid deletion occurred at the first pair of hydrophobic residues. However, random amino acid substitutions in this region did not affect assembly. The results indicated that the hhr region of the core protein was necessory for capsid assembly of woodchuck hepatitis virus.
出处
《复旦学报(自然科学版)》
CAS
CSCD
北大核心
1998年第4期579-580,共2页
Journal of Fudan University:Natural Science
关键词
乙型肝炎病毒
核心蛋白
氨基酸
WHV
nucleocapsid of hepadnaviruses
the core proteins
amino acid substitutions