title: Interaction of synthetic HPV-16 capsid peptides with heparin: thermodynamic parameters and binding mechanism.
abstract: Capsid proteins binding cell surface proteoglycans is a key early event in human papillomavirus (HPV) infection. The positively charged sequences at the C-terminus of the L1 protein and the N- and C-termini of the L2 protein of HPV-16 can efficiently bind to heparin receptors, which were characterized in the present study by quantitative isothermal titration calorimetry experiments primarily, fluorescence spectroscopy, and static right-angle light scattering. The binding constant, K, was at an order of magnitude of 10(7) M(-1) for the two peptides at the N- and C-termini of HPV-16 L2 and segment b at the C-terminus of HPV-16 L1, while that for other L1 analogues were of a smaller order, illustrating that the heparin binding is a typical sequence-specific and -dependent phenomenon. These results suggest that, in addition to L1, the L2 protein may participate in cell surface attachment during HPV infection. Furthermore, the calorimetry results demonstrated that hydrophobic interactions and hydrogen bonding are involved in peptide binding to heparin in addition to the essential electrostatic interactions. Meanwhile, circular dichroism spectroscopy revealed that binding to heparin does not induce obvious secondary structural changes in the peptides.
authors.affiliation: State Key Laboratory for Supramolecular Structure and Materials, Jilin University, No. 2699, Qianjin Street, Changchun 130012, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.forename: Ji-Sheng
authors.initials: JS
authors.lastname: Yu
authors.forename: Shi
authors.initials: S
authors.lastname: Jin
authors.forename: Xiao
authors.initials: X
authors.lastname: Zha
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Wu
authors.forename: Zhiwu
authors.initials: Z
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D002151:Calorimetry; D036022:Capsid Proteins / Q000138:chemical synthesis / Q000737:chemistry*; D006493:Heparin / Q000737:chemistry*; D052162:Human papillomavirus 16 / Q000378:metabolism*; D006801:Humans; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D036022:Capsid Proteins; D010455:Peptides; D006493:Heparin