Identification of an Arabidopsis transmembrane bZIP transcription factor involved in the endoplasmic reticulum stress response.
Among 75 bZIP transcription factors identified in Arabidopsis, 3 (AtbZIP17, AtbZIP28, and AtbZIP49) possess a putative transmembrane domain (TMD) in addition to AtbZIP60, which was characterized previously. In the present study, cDNAs of AtbZIP17 and AtbZIP28 were isolated. Truncated forms of AtbZIP17 and AtbZIP28 lacking the C-terminal domain including TMD were examined as putative active forms. One of them, AtbZIP28DeltaC, activated BiP1 and BiP3 promoters through the cis-elements P-UPRE and ERSE responsible for the ER stress response. Subsequently, a fusion protein of green fluorescent protein (GFP) and AtbZIP28 was expressed in Arabidopsis cultured cells. Under non-stress conditions, GFP fluorescence localization almost overlapped with an ER marker; however, tunicamycin and dithiothreitol treatment clearly increased GFP fluorescence in the nucleus suggesting that the N-terminal fragment of AtbZIP28 translocates to the nucleus in response to ER stress.
Tajima
Hiromi
H
Graduate school of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
Iwata
Yuji
Y
Iwano
Megumi
M
Takayama
Seiji
S
Koizumi
Nozomu
N
D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D004229:Dithiothreitol / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014415:Tunicamycin / Q000494:pharmacology
D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; C525259:bZIP17 protein, Arabidopsis; C530495:bZIP28 protein, Arabidopsis; D014415:Tunicamycin; D049452:Green Fluorescent Proteins; D004229:Dithiothreitol