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Intercapsomeric disulfide bonds in papillomavirus assembly and disassembly
被引:100
作者:
Li, ML
Beard, P
Estes, PA
Lyon, MK
Garcea, RL
机构:
[1] Univ Colorado, Hlth Sci Ctr, Sect Pediat Hematol Oncol, Sch Med,Dept Pediat, Denver, CO 80262 USA
[2] Swiss Inst Expt Canc Res, CH-1066 Epalinges, Switzerland
[3] Univ Colorado, Dept Mol Cellular & Dev Biol, Boulder, CO 80309 USA
关键词:
D O I:
10.1128/JVI.72.3.2160-2167.1998
中图分类号:
Q93 [微生物学];
学科分类号:
071005 ;
100705 ;
摘要:
In order to analyze bonding contacts that stabilize the virion or promote capsid assembly, bovine papillomavirus (BPV) virions cr ere subjected to buffer conditions known to disrupt polyomavirus, virions. At physiologic ionic strength, incubation with dithiothreitol (DTT), EGTA or DTT plus EGTA did not disrupt BPV virions as determined by electron microscopy. However, incubation of virions with DTT rendered the BPV L1 protein susceptible to trypsin cleavage at its carboxy terminus and rendered the genome susceptible to digestion with DNase I, When DTT-treated BPV virions were analyzed by analytical ultracentrifugation, they sedimented at 230S compared with 273S for untreated virions, suggesting a capsid shell expansion, Incubation with EGTA had no effect on trypsin or DNase I sensitivity and only a small effect upon the virion S value, A single cysteine residue conserved among BPV and human papillomavirus (HPV) L1 proteins resides within the trypsin-sensitive carboxy terminus of L1, which is required for capsid assembly, A recombinant HPV type 11 L1 protein, which was purified after expression in Escherichia coli and which has a Cys-to-Gly change at this position (Cys424), formed pentamers; however, unlike the wild-type protein, these mutant pentamers could no longer assemble in vitro into capsid-like structures, These results indicate an important role for interpentamer disulfide bonds in papillomavirus capsid assembly and disassembly and suggest a mechanism of virus uncoating in the reducing environment of the cytoplasm.
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页码:2160 / 2167
页数:8
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