title: AL1-dependent repression of transcription enhances expression of Tomato golden mosaic virus AL2 and AL3.
abstract: Studies using Nicotiana benthamiana protoplasts have determined that repression of upstream transcription by AL1 protein enhances AL2 and AL3 expression in Tomato golden mosaic virus (TGMV). Mutations resulting in the inability of TGMV AL1 protein to associate with its cognate binding site, result in a decrease in both AL2 and AL3 expression. Reduced expression correlates with an increase in transcription from the AL62 start site, and decreased transcription from downstream initiation sites (AL1935 and AL1629) present within the AL1 coding region. The results demonstrate that, in a tobacco protoplast system, repression of AL62 transcription, regulated through binding of AL1 protein to sequences in the origin of replication, is required prior to AL2 and AL3 gene expression from the AL1935 and AL1629 viral transcripts. This provides a mechanism to regulate expression of AL2, which is involved in suppression of host defense responses and is required for late gene expression.
authors.affiliation: Department of Biology, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA.
authors.forename: Chia-Yi
authors.initials: CY
authors.lastname: Shung
authors.forename: Garry
authors.initials: G
authors.lastname: Sunter
mesh_terms: D001483:Base Sequence; D053839:Begomovirus / Q000235:genetics* / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005814:Genes, Viral; D018551:Solanum lycopersicum / Q000821:virology; D011401:Promoter Regions, Genetic; D011523:Protoplasts / Q000821:virology; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000821:virology; D014162:Transfection; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C483731:AL2 protein, Begomovirus; D017931:DNA Primers; D004279:DNA, Viral; D012367:RNA, Viral; D012097:Repressor Proteins; D014764:Viral Proteins; C080288:replication protein AL1, Begomovirus