Nucleic acid binding properties of the nucleic acid chaperone domain of hepatitis delta antigen.
The N terminal region of hepatitis delta antigen (HDAg), referred to here as NdAg, has a nucleic acid chaperone activity that modulates the ribozyme activity of hepatitis delta virus (HDV) RNA and stimulates hammerhead ribozyme catalysis. We characterized the nucleic acid binding properties of NdAg, identified the structural and sequence domains important for nucleic acid binding, and studied the correlation between the nucleic acid binding ability and the nucleic acid chaperone activity. NdAg does not recognize the catalytic core of HDV ribozyme specifically. Instead, NdAg interacts with a variety of nucleic acids and has higher affinities to longer nucleic acids. The studies with RNA homopolymers reveal that the binding site size of NdAg is around nine nucleotides long. The extreme N terminal portion of NdAg, the following coiled-coil domain and the basic amino acid clusters in these regions are important for nucleic acid binding. The nucleic acid-NdAg complex is stabilized largely by electrostatic interactions. The formation of RNA-protein complex appears to be a prerequisite for facilitating hammerhead ribozyme catalysis of NdAg and its derivatives. Mutations that reduce the RNA binding activity or high ionic strength that destabilizes the RNA-protein complex, reduce the nucleic acid chaperone activity of NdAg.
Wang
Chun-Chung
CC
Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan, Republic of China.
Chang
Tsung-Cheng
TC
Lin
Ching-Wen
CW
Tsui
Hsiu-Ling
HL
Chu
Page B C
PB
Chen
Bo-Shun
BS
Huang
Zhi-Shun
ZS
Wu
Huey-Nan
HN
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive; D002942:Circular Dichroism; D003698:Hepatitis Delta Virus / Q000235:genetics / Q000378:metabolism*; D035923:Hepatitis delta Antigens / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D016337:RNA, Catalytic / Q000378:metabolism; D012367:RNA, Viral / Q000737:chemistry / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D035923:Hepatitis delta Antigens; D046911:Macromolecular Substances; D016337:RNA, Catalytic; D012367:RNA, Viral; D016601:RNA-Binding Proteins