Functional domains and DNA-binding sequences of RFLAT-1/KLF13, a Krüppel-like transcription factor of activated T lymphocytes.
RFLAT-1/KLF13, a member of the Krüppel-like family of transcription factors, was identified as a transcription factor expressed 3-5 days after T lymphocyte activation. It binds to the promoter of the chemokine gene RANTES (regulated on activation normal T cell expressed and secreted) and regulates its "late" expression in activated T-cells. In this study, a series of experiments to define the functional domains of RFLAT-1/KLF13 were undertaken to further advance the understanding of the molecular mechanisms underlying transcriptional regulation by this factor. Using the GAL4 fusion system, distinct transcriptional activation and repression domains were identified. The RFLAT-1 minimum activation domain is localized to amino acids 1-35, whereas the repression domain resides in amino acids 67-168. Deletion analysis on the RFLAT-1 protein further supports these domain functions. The RFLAT-1 activation domain is similar to that of its closest family member, basic transcription element-binding protein 1. This domain is highly hydrophobic, and site-directed mutagenesis demonstrated that both negatively charged and hydrophobic residues are important for transactivation. The nuclear localization signal of RFLAT-1 was also identified using the RFLAT-1/green fluorescence protein fusion approach. RFLAT-1 contains two potent, independent nuclear localization signals; one is immediately upstream of the zinc finger DNA-binding domain, and the other is within the zinc fingers. Using mutational analysis, we also determined that the critical binding sequence of RFLAT-1 is CTCCC. The intact CTCCC box on the RANTES promoter is necessary for RFLAT-1-mediated RANTES transcription and is also required for the synergy between RFLAT-1 and NF-kappaB proteins.
Song
An
A
Department of Pediatrics, Stanford University School of Medicine, Stanford, California 94305-5164, USA.
Patel
Anita
A
Thamatrakoln
Kimberlee
K
Liu
Chian
C
Feng
Dongdong
D
Clayberger
Carol
C
Krensky
Alan M
AM
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D019556:COS Cells; D018797:Cell Cycle Proteins; D004247:DNA / Q000378:metabolism*; D018076:DNA, Complementary; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D051741:Kruppel-Like Transcription Factors; D008213:Lymphocyte Activation; D051379:Mice; D008969:Molecular Sequence Data; D010802:Phylogeny; D012097:Repressor Proteins; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation
D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C486423:KLF13 protein, human; C486422:Klf13 protein, mouse; D051741:Kruppel-Like Transcription Factors; D012097:Repressor Proteins; D014157:Transcription Factors; D004247:DNA