Regulation of MSV and WDV virion-sense promoters by WDV nonstructural proteins: a role for their retinoblastoma protein-binding motifs.
In this work we demonstrate that wheat dwarf virus (WDV) RepA can activate WDV and maize streak virus (MSV) virion (V)-sense expression in plant tissues. Rep alone does not have any effect on the silent WDV promoter and it represses the basal MSV promoter activity. MSV promoter activation by RepA depends on an intact RepA retinoblastoma protein (RB)-binding domain. Promoter repression by Rep also depends on this domain to some extent. Mutation of the RepA RB-binding domain has no effect on WDV promoter activation. The WDV promoter contains two sites that fit the consensus E2F-binding site. One, WDV1, binds human E2F-1 in one-hybrid assays in yeast. It also binds specifically to maize and wheat proteins in vitro and, when fused to a minimal 35S promoter, it confers responsiveness to RepA only when the RepA RB-binding domain and the WDV1 site are intact. In the whole WDV V-sense promoter context, mutations of this sequence have no effect, suggesting that additional sequences are important for RepA-mediated promoter activation.
Muñoz-Martín
Angeles
A
Facultad de Ciencias del Medio Ambiente, Universidad de Castilla-La Mancha, E-45071, Toledo, Spain.
Collin
Sylvie
S
Herreros
Esther
E
Mullineaux
Philip M
PM
Fernández-Lobato
María
M
Fenoll
Carmen
C
D020816:Amino Acid Motifs; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D018797:Cell Cycle Proteins; D004265:DNA Helicases; D004279:DNA, Viral / Q000235:genetics; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D017791:Geminiviridae / Q000235:genetics* / Q000378:metabolism; D016679:Genome, Viral; D006801:Humans; D066298:In Vitro Techniques; D026762:Maize streak virus / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism; D015534:Trans-Activators; D014157:Transcription Factors / Q000378:metabolism; D014908:Triticum / Q000378:metabolism / Q000821:virology; D020798:Two-Hybrid System Techniques; D017361:Viral Nonstructural Proteins / Q000235:genetics* / Q000378:metabolism; D003313:Zea mays / Q000378:metabolism / Q000821:virology
D018797:Cell Cycle Proteins; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D009687:Nuclear Proteins; D010940:Plant Proteins; D011506:Proteins; D016160:Retinoblastoma Protein; D015534:Trans-Activators; D014157:Transcription Factors; D017361:Viral Nonstructural Proteins; C045264:replication initiator protein; D004265:DNA Helicases