The 5' UTR negatively regulates quantitative and spatial expression from the ABI3 promoter.
The involvement of transcription factors Arabidopsis abscisic acid-insensitive3 (ABI3), maize viviparous1 (VP1) and Phaseolus vulgaris ABI3-like factor (PvALF) in the spatial control of storage protein gene expression is well established. However, little insight exists as to how they are themselves regulated. To address this, a 5.15 kb ABI3 upstream sequence including a 4.6 kb full-length promoter and 519 bp of 5'-untranslated region (UTR) was used to drive either beta-glucuronidase (GUS) or green fluorescent protein (GFP) expression in Arabidopsis. Expression from the full-length (- 4630/ + 519ABI3 ) and various 5'-truncated promoters was detected during embryogenesis in all lines, except those transgenic for promoter elements shorter than 364 bp. Two upstream activating regions, -3600 to -2033 and -2033 to -882, enhanced GUS expression in seeds. The -882 to -364 region was sufficient to confer seed-specific expression of GUS when fused to a - 64/ + 6CaMV 35S minimal promoter. Expression from the ABI3 promoter constructs was seed-specific, except in the presence of exogenous abscisic acid (ABA) (>0.3 microM), when GUS expression was detected in seedling roots. Excision of a 405 bp region containing three upstream open reading frames (uORFs) from the 5'-UTR dramatically increased GUS expression and debilitated constraint of reporter expression in roots. Negative regulation of ABI3 expression by the 5'-UTR may involve a post-transcriptional mechanism analogous to that of tumor suppressor genes which also bear long, uORF-containing, 5'-UTRs, or through interactions with RNA-binding proteins.
Ng
Danny W-K
DW
Institute of Developmental and Molecular Biology, Department of Biology, Texas A&M University, College Station, TX 77843-3155, USA.
Chandrasekharan
Mahesh B
MB
Hall
Timothy C
TC
D024506:5' Flanking Region / Q000235:genetics*; D000040:Abscisic Acid / Q000494:pharmacology; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000196:embryology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics*; D001483:Base Sequence; D003624:Darkness; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins; D008027:Light; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D012639:Seeds / Q000235:genetics / Q000254:growth & development; D014157:Transcription Factors
C091601:ABI3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D008164:Luminescent Proteins; D010937:Plant Growth Regulators; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D000040:Abscisic Acid; D005966:Glucuronidase