TY - JOUR
T1 - Identification of a novel dimer stabilization region in a plant bZIP transcription activator
AU - Katagiri, Fumiaki
AU - Seipel, Katja
AU - Chua, Nam Hai
PY - 1992/11
Y1 - 1992/11
N2 - We have carried out deletion analyses of a tobacco transcription activator, TGA1a, in order to define its functional domains. TGA1a belongs to the basic-region-leucine zipper (bZIP) class of DNA-binding proteins. Like other proteins of this class, it binds to its target DNA as a dimer, and its bZIP domain is necessary and sufficient for specific DNA binding. A mutant polypeptide containing the bZIP domain alone, however, shows a lower DNA-binding affinity than the full-length TGA1a. The C-terminal portion of TGA1a, which is essential for the higher DNA-binding affinity, contains a polypeptide region that can stabilize dimeric forms of the protein. This polypeptide region is designated the dimer stabilization (DS) region. Under our in vitro conditions, TGA1a derivatives with the DS region and those without the region do not form a detectable mixed dimer. This result indicates that in addition to the leucine zipper, the DS region can serve as another determinant of the dimerization specificity of TGA1a. In fact, the DS region, when fused to another bZIP protein, C/EBP, can inhibit dimer formation between the fusion protein and native C/EBP, whereas each of these can form homodimers. Such a portable determinant of dimerization specificity has potential application in studies of DNA-binding proteins as well as in biotechnology.
AB - We have carried out deletion analyses of a tobacco transcription activator, TGA1a, in order to define its functional domains. TGA1a belongs to the basic-region-leucine zipper (bZIP) class of DNA-binding proteins. Like other proteins of this class, it binds to its target DNA as a dimer, and its bZIP domain is necessary and sufficient for specific DNA binding. A mutant polypeptide containing the bZIP domain alone, however, shows a lower DNA-binding affinity than the full-length TGA1a. The C-terminal portion of TGA1a, which is essential for the higher DNA-binding affinity, contains a polypeptide region that can stabilize dimeric forms of the protein. This polypeptide region is designated the dimer stabilization (DS) region. Under our in vitro conditions, TGA1a derivatives with the DS region and those without the region do not form a detectable mixed dimer. This result indicates that in addition to the leucine zipper, the DS region can serve as another determinant of the dimerization specificity of TGA1a. In fact, the DS region, when fused to another bZIP protein, C/EBP, can inhibit dimer formation between the fusion protein and native C/EBP, whereas each of these can form homodimers. Such a portable determinant of dimerization specificity has potential application in studies of DNA-binding proteins as well as in biotechnology.
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U2 - 10.1128/MCB.12.11.4809
DO - 10.1128/MCB.12.11.4809
M3 - Article
C2 - 1406663
AN - SCOPUS:0026722360
SN - 0270-7306
VL - 12
SP - 4809
EP - 4816
JO - Molecular and cellular biology
JF - Molecular and cellular biology
IS - 11
ER -