Published online May 12, 2017. doi: 10.5501/wjv.v6.i2.26
Peer-review started: December 25, 2016
First decision: January 16, 2017
Revised: February 8, 2017
Accepted: February 28, 2017
Article in press: March 2, 2017
Published online: May 12, 2017
To further characterize the structure and nucleic acid binding properties of the 195 amino acid small delta antigen, S-HDAg, a study was made of a truncated form of S-HDAg, comprising amino acids 61-195 (∆60HDAg), thus lacking the domain considered necessary for dimerization and higher order multimerization.
Circular dichroism, and nuclear magnetic resonance experiments were used to assess the structure of ∆60HDAg. Nucleic acid binding properties were investigated by gel retardation assays.
Results showed that the truncated ∆60HDAg protein is intrinsically disordered but compact, whereas the RNA binding domain, comprising residues 94-146, adopts a dynamic helical conformation. We also found that ∆60HDAg fails to multimerize but still contains nucleic acid binding activity, indicating that multimerization is not essential for nucleic acid binding. Moreover, in agreement with what has been previously reported for full-length protein, no apparent specificity was found for the truncated protein regarding nucleic acid binding.
Taken together these results allowed concluding that ∆60HDAg is intrinsically disordered but compact; ∆60HDAg is not a multimer but is still capable of nucleic acid binding albeit without apparent specificity.
Core tip: The characterization of a truncated form of S-HDAg lacking amino acids 1-60, ∆60HDAg is reported. Structure of ∆60HDAg was assessed by circular dichroism and nuclear magnetic resonance and its nucleic acid binding properties were investigated using gel retardation assays. This study demonstrates for the first time that ∆60HDAg is intrinsically disordered and a monomer. Furthermore, ∆60HDAg can bind a wide variety of nucleic acids without apparent specificity.