Open AccessEvidence for Nucleic Acid Binding Ability and Nucleosome Association of Bombyx mori Nucleopolyhedrovirus BRO Proteins
Author(s) -
Evgeny A. Zemskov,
Won Kyung Kang,
Susumu Maeda
Publication year - 2000
Publication title -
journal of virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.617
H-Index - 292
eISSN - 1070-6321
pISSN - 0022-538X
DOI - 10.1128/jvi.74.15.6784-6789.2000
Subject(s) - biology , micrococcal nuclease , histone , dna , nucleosome , nucleic acid , chromatin , microbiology and biotechnology , nuclease , dna binding protein , cytoplasm , biochemistry , gene , transcription factor
TheBombyx mori nucleopolyhedrovirus (BmNPV) genome contains five related members of thebro gene family, all of which are actively expressed in infected BmN cells. Although their functions are unknown, their amino acid sequences contain a motif found in all known viral and prokaryotic single-stranded DNA binding proteins. To determine if they bind to nucleic acids, we fractionated the nuclei of BmNPV-infected BmN cells using a histone extraction protocol. We detected BRO-A, BRO-C, and BRO-D in the histone H1 fraction using anti-BRO antibodies. Micrococcal nuclease treatment released these BRO proteins from the chromatin fraction, suggesting their involvement in nucleosome structures. Chromatographic fractionation showed that BRO-A and/or BRO-C interacted with core histones. Expression of partial sequences of BRO-A proved that the N-terminal 80 amino acid residues were required for DNA binding activity. We also demonstrated that BmNPV BRO proteins underwent phosphorylation and ubiquitination followed by proteasome degradation, which may explain their distribution in the cytoplasm as well as the nucleus. We propose that BRO-A and BRO-C may function as DNA binding proteins that influence host DNA replication and/or transcription.