An inhibitory carboxyl-terminal domain in Ets-1 and Ets-2 mediates differential binding of ETS family factors to promoter sequences of the mb-1 gene.
The mb-1 gene is expressed only during the early stages of B-lymphocyte differentiation. Here we show that the mb-1 proximal promoter region contains a functionally important binding site for members of the ETS family of DNA-binding proteins. We found that both the E26 virus-encoded v-ets and the myeloid/B-cell-specific factor PU.1 bind efficiently to this site in vitro. By contrast, Ets-1, the lymphocyte-specific cellular homologue of v-ets, and the related, more ubiquitously expressed Ets-2 protein interacted weakly with this binding site. DNA binding by both Ets-1 and Ets-2, however, could be increased 20- to 50-fold by deleting as few as 16 carboxyl-terminal amino acids. The inhibitory carboxyl-terminal amino acid sequence is highly conserved between Ets-1 and Ets-2 but is not present in either v-ets or PU.1. Replacement of the carboxyl-terminal amino acids of v-ets with those of Ets-1 decreased DNA binding by v-ets drastically. Cotranslation of Ets-1 transcripts encoding proteins of different lengths suggested that Ets-1 binds DNA as a monomer. Therefore, the carboxyl-terminal inhibitory domain appears to interfere directly with DNA binding and not with homodimerization. Finally, the functional relevance of ETS factor binding to the mb-1 promoter site was evidenced by the stimulation of transcription through this site by a v-myb-v-ets fusion protein. Together, these data suggest that one or more ETS family factors are involved in the regulation of mb-1 gene expression.
Hagman
J
J
Howard Hughes Medical Institute, Department of Microbiology and Immunology, University of California, San Francisco 94143-0414.
Grosschedl
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000502:physiology; D001483:Base Sequence; D001665:Binding Sites; D002454:Cell Differentiation / Q000235:genetics; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D015870:Gene Expression; D008969:Molecular Sequence Data; D005810:Multigene Family; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D009857:Oncogenes; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D050784:Proto-Oncogene Protein c-ets-1; D050787:Proto-Oncogene Protein c-ets-2; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D050783:Proto-Oncogene Proteins c-ets; D011519:Proto-Oncogenes; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D012097:Repressor Proteins; D015183:Restriction Mapping; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015534:Trans-Activators; D014157:Transcription Factors; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; C107465:ERF protein, human; C494041:ETS1 protein, human; D009838:Oligodeoxyribonucleotides; D050784:Proto-Oncogene Protein c-ets-1; D050787:Proto-Oncogene Protein c-ets-2; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D015682:Retroviridae Proteins, Oncogenic; D015534:Trans-Activators; D014157:Transcription Factors; C050379:oncogene proteins v-ets; D015500:Chloramphenicol O-Acetyltransferase; D011505:Protein-Tyrosine Kinases