Taxonomic distribution of proteins containing Bro-N domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing Bro-N domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

Evidence for nucleic acid binding ability and nucleosome association ofBombyx mori nucleopolyhedrovirus BRO proteins.

Zemskov EA, Kang W, Maeda S
J Virol. 2000; 74: 6784-9

The Bombyx mori nucleopolyhedrovirus (BmNPV) genome contains five relatedmembers of the bro gene family, all of which are actively expressed ininfected BmN cells. Although their functions are unknown, their amino acidsequences contain a motif found in all known viral and prokaryoticsingle-stranded DNA binding proteins. To determine if they bind to nucleicacids, we fractionated the nuclei of BmNPV-infected BmN cells using ahistone extraction protocol. We detected BRO-A, BRO-C, and BRO-D in thehistone H1 fraction using anti-BRO antibodies. Micrococcal nucleasetreatment released these BRO proteins from the chromatin fraction,suggesting their involvement in nucleosome structures. Chromatographicfractionation showed that BRO-A and/or BRO-C interacted with corehistones. Expression of partial sequences of BRO-A proved that theN-terminal 80 amino acid residues were required for DNA binding activity.We also demonstrated that BmNPV BRO proteins underwent phosphorylation andubiquitination followed by proteasome degradation, which may explain theirdistribution in the cytoplasm as well as the nucleus. We propose thatBRO-A and BRO-C may function as DNA binding proteins that influence hostDNA replication and/or transcription.

The genome of Melanoplus sanguinipes entomopoxvirus.

Afonso CL, Tulman ER, Lu Z, Oma E, Kutish GF, Rock DL
J Virol. 1999; 73: 533-52

The family Poxviridae contains two subfamilies: the Entomopoxvirinae(poxviruses of insects) and the Chordopoxvirinae (poxviruses ofvertebrates). Here we present the first characterization of the genome ofan entomopoxvirus (EPV) which infects the North American migratorygrasshopper Melanoplus sanguinipes and other important orthopteran pests.The 236-kbp M. sanguinipes EPV (MsEPV) genome consists of a central codingregion bounded by 7-kbp inverted terminal repeats and contains 267 openreading frames (ORFs), of which 107 exhibit similarity to previouslydescribed genes. The presence of genes not previously described inpoxviruses, and in some cases in any other known virus, suggestssignificant viral adaptation to the arthropod host and the externalenvironment. Genes predicting interactions with host cellular mechanismsinclude homologues of the inhibitor of apoptosis protein, stress responseprotein phosphatase 2C, extracellular matrixin metalloproteases,ubiquitin, calcium binding EF-hand protein, glycosyltransferase, and atriacylglyceride lipase. MsEPV genes with putative functions in preventionand repair of DNA damage include a complete base excision repair pathway(uracil DNA glycosylase, AP endonuclease, DNA polymerase beta, and anNAD+-dependent DNA ligase), a photoreactivation repair pathway(cyclobutane pyrimidine dimer photolyase), a LINE-type reversetranscriptase, and a mutT homologue. The presence of these specific repairpathways may represent viral adaptation for repair of environmentallyinduced DNA damage. The absence of previously described poxvirus enzymesinvolved in nucleotide metabolism and the presence of a novel thymidylatesynthase homologue suggest that MsEPV is heavily reliant on host cellnucleotide pools and the de novo nucleotide biosynthesis pathway. MsEPVand lepidopteran genus B EPVs lack genome colinearity and exhibit a lowlevel of amino acid identity among homologous genes (20 to 59%), perhapsreflecting a significant evolutionary distance between lepidopteran andorthopteran viruses. Divergence between MsEPV and the Chordopoxvirinae isindicated by the presence of only 49 identifiable chordopoxvirushomologues, low-level amino acid identity among these genes (20 to 48%),and the presence in MsEPV of 43 novel ORFs in five gene families. Genescommon to both poxvirus subfamilies, which include those encoding enzymesinvolved in RNA transcription and modification, DNA replication, proteinprocessing, virion assembly, and virion structural proteins, define thegenetic core of the Poxviridae.