Fine structure and function of the osmotin gene promoter.
The gene encoding osmotin, a tobacco pathogenesis-related protein, has been shown to be regulated by an array of hormonal and environmental signals. The osmotin promoter fragment -248 to -108 upstream of the transcription start site (fragment A), was sufficient to direct reporter gene expression when fused to a minimal CaMV 35S promoter in transient assays using microprojectile bombardment. This was consistent with previous 5'-deletion analyses of the osmotin promoter which showed that the promoter sequence from -248 to -108 is absolutely required for reporter gene activity. Nuclear protein factors from salt-adapted tobacco cells, ABA-treated unadapted cells, and young cultured tobacco leaves were shown to interact with fragment A by gel mobility-shift assays. DNase I footprinting revealed that three conserved promoter elements in fragment A interact specifically with nuclear factors. These elements are: (1) a cluster of G-box-like sequences (G sequence); (2) an AT-1 box-like sequence, 5'-AATTATTTTATG-3' (AT sequence); (3) a sequence highly conserved in ethylene-induced PR gene promoters, 5'-TAAGA/CGCCGCC-3' (PR sequence). Transient expression assays performed with fragment A deletions fused to GUS indicated that osmotin promoter activity correlated with the presence of these elements. UV cross-linking analysis showed that the protein complex bound to fragment A consisted of at least four individual proteins with approximate molecular masses of 28, 29, 40 and 42 kDa. One component of this protein complex, which was associated with the G sequence, was a 14-3-3 like protein.
Liu
D
D
Center for Plant Environmental Stress Physiology, Purdue University, West Lafayette, IN 47907-1165, USA.
Narasimhan
M L
ML
Xu
Y
Y
Raghothama
K G
KG
Hasegawa
P M
PM
Bressan
R A
RA
D001483:Base Sequence; D017796:Caulimovirus / Q000235:genetics; D002478:Cells, Cultured; D004247:DNA; D018983:DNA Footprinting; D003850:Deoxyribonuclease I / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D010947:Plants, Toxic; D011401:Promoter Regions, Genetic; D014026:Nicotiana / Q000166:cytology / Q000235:genetics
D010940:Plant Proteins; C073139:osmotin protein, Nicotiana tabacum; D004247:DNA; D003850:Deoxyribonuclease I