Journal of Microbiology

Research Support, Non-U.S. Gov't

Function of VP2 Protein in the Stability of the Secondary Structure of Virus-like Particles of Genogroup II Norovirus at Different pH Levels: Function of VP2 Protein in the Stability of NoV VLPs: Yao Lin , Li Fengling , Wang Lianzhu , Zhai Yuxiu , Jiang Yanhua; J. Microbiol. 2014;52(11):970-975. Published online October 3, 2014; DOI: https://doi.org/10.1007/s12275-014-4323-6

Abstract: VP2 is the minor structural protein of noroviruses (NoV) and may function in NoV particle stability. To determine the function of VP2 in the stability of the NoV particle, we constructed and purified two kinds of virus-like particles (VLPs), namely, VLPs (VP1) and VLPs (VP1+VP2), from Sf9 cells infected with recombinant baculoviruses by using a Bac-to-Bac? baculovirus expression system. The two kinds of VLPs were treated with different phosphate buffers (pH 2 to pH 8); the secondary structure was then analyzed by far UV circular dichroism (CD) spectroscopy. Results showed that significant disruptions of the secondary structure of proteins were not observed at pH 2 to pH 7. At pH 8, the percentages of α-helix, β-sheet, and β-turn in VLPs (VP1) were decreased from 11% to 8%, from 37% to 32%, and from 20% to 16%, respectively. The percentage of coil was increased from 32% to 44%. By contrast, the percentages of α-helix, β-sheet, and β-turn in VLPs (VP1+VP2) were decreased from 11% to 10%, from 37% to 35%, and from 20% to 19%, respectively. The percentage of coil was increased from 32% to 36%. VLPs (VP1+VP2) was likely more stable than VLPs (VP1), as indicated by the percentage of the secondary structures analyzed by CD. These results suggested that VP2 could stabilize the secondary structure of VLPs under alkaline pH conditions. This study provided novel insights into the molecular mechanism of the function of VP2 in the stability of NoV particles.

Secondary Structure Analysis of Amino Terminal Domain in Phage Lambda Integrase: Yu, Jeong A , Nam, Chan Eun , Cho, Eun Hee; J. Microbiol. 1998;36(4):266-272.

Abstract: The amino-terminal domain of bacteriophage λ integrase recognizes specific DNA sequences called arm-type sites. To study the structural and functional relationships of the integras armtype DNA binding domains were confirmed by gel mobility-shift assay. The polypeptides were subjected to circular dichroism spectroscopy to estimate the amount of secondary structures they contain Based upon analyses of circular dichroism spectra and comparison with predicted secondary structural compositions, it was estimated that the amino terminal domain of integrase in an aqueous solution was composed of a little α-helical region. The helical content increased with an increasing amount of ethanol, an α-helix inducer. This indicates that its conformation can be changed to a form with higher content of α-helical structure under a certain condition.

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