Structure-function analysis of TFII-I. Roles of the N-terminal end, basic region, and I-repeats.
The transcription factor TFII-I can bind specifically to several DNA sequence elements and is implicated in both basal and activated transcription. There are four alternatively spliced isoforms of TFII-I, all characterized by the presence of six I-repeats, R1-R6, each containing a potential helix-loop-helix motif implicated in protein-protein interactions. These isoforms exhibit both homomeric and heteromeric interactions that lead to nuclear localization. In this study we mapped two distinct regions in TFII-I that affect its DNA binding. Deletion of either of these regions led to abrogation of DNA binding and transcriptional activation from both the Vbeta and c-fos promoters. The I-repeats, as expected, were capable of mediating homomeric interactions either individually or in combination. Unexpectedly, an additional homomeric interaction domain was found within the N-terminal end of TFII-I that includes a putative leucine zipper motif. These data suggest a model in which TFII-I undergoes regulated homomeric interaction mediated by both the N-terminal end and the I-repeats.
Cheriyath
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Department of Pathology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
Roy
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D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000737:chemistry; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis / Q000737:chemistry* / Q000502:physiology; D018257:Helix-Loop-Helix Motifs; D020449:Repetitive Sequences, Amino Acid; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000032:analysis / Q000737:chemistry* / Q000502:physiology; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D014157:Transcription Factors; D004247:DNA