The minimal transactivation domain of the basic motif-leucine zipper transcription factor NRL interacts with TATA-binding protein.
The basic motif-leucine zipper (bZIP) transcription factor NRL controls the expression of rhodopsin and other phototransduction genes and is a key mediator of photoreceptor differentiation. To delineate the molecular mechanisms underlying transcriptional initiation of rod-specific genes, we characterized different regions of the NRL protein using yeast-based autoactivation assays. We identified 35 amino acid residues in the proline- and serine-rich N-terminal region (called minimal transactivation domain, MTD), which, when combined with LexA or Gal4 DNA binding domains, exhibited activation of target promoters. Because this domain is conserved in all proteins of the large Maf family, we hypothesized that NRL-MTD played an important role in assembling the transcription initiation complex. Our studies showed that the NRL protein, including the MTD, interacted with full-length or the C-terminal domain of TATA-binding protein (TBP) in vitro. NRL and TBP could be co-immunoprecipitated from bovine retinal nuclear extract. TBP was also part of c-Maf and MafA (two other large Maf proteins)-containing complex(es) in vivo. Our data suggest that the function of NRL-MTD is to activate transcription by recruiting or stabilizing TBP (and consequently other components of the general transcription complex) at the promoter of target genes, and a similar function may be attributed to other bZIP proteins of the large Maf family.
Department of Ophthalmology, WK Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan 48105, USA.
James S
JS
Friedman
Hemant
H
Khanna
Prabodh K
PK
Swain
Raphael
R
Denicola
Hong
H
Cheng
Kenneth P
KP
Mitton
Christian H
CH
Weber
David
D
Hicks
Anand
A
Swaroop
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry; D050976:Basic-Leucine Zipper Transcription Factors; D002417:Cattle; D002467:Cell Nucleus / Q000378:metabolism; D018360:Crystallography, X-Ray; D017931:DNA Primers / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics*; D004789:Enzyme Activation; D005136:Eye Proteins / Q000737:chemistry* / Q000235:genetics*; D006801:Humans; D047468:Immunoprecipitation; D016350:Leucine Zippers; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014176:Protein Biosynthesis; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012160:Retina / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry; D012697:Serine Endopeptidases / Q000737:chemistry; D035181:TATA-Box Binding Protein / Q000737:chemistry* / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D001616:beta-Galactosidase / Q000378:metabolism; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D017931:DNA Primers; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D005136:Eye Proteins; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases; D035181:TATA-Box Binding Protein; D014157:Transcription Factors; D001616:beta-Galactosidase; D000099160:LexA Repressor Protein; C052130:GAL4 protein, S cerevisiae; C490037:NRL protein, human