scholarly journals Aryl hydrocarbon (Ah) receptor DNA-binding activity. Sequence specificity and Zn2+ requirement.

1990 ◽  
Vol 265 (16) ◽  
pp. 9251-9258
Author(s):  
F Saatcioglu ◽  
D J Perry ◽  
D S Pasco ◽  
J B Fagan
Keyword(s):  
Dna Binding ◽  
Binding Activity ◽  
Ah Receptor ◽  
Sequence Specificity ◽  
Aryl Hydrocarbon ◽  
Dna Binding Activity ◽  
Activity Sequence

Transformation by Fos proteins requires a C-terminal transactivation domain

1993 ◽  
Vol 13 (12) ◽  
pp. 7429-7438
Author(s):  
R Wisdon ◽  
I M Verma
Keyword(s):  
Dna Binding ◽  
Leucine Zipper ◽  
Fibroblast Cell ◽  
Binding Activity ◽  
Sequence Specificity ◽  
Transactivation Domain ◽  
Functional Requirements ◽  
Dna Binding Activity ◽  
The Difference ◽  
Transforming Proteins

The Fos family of proteins now includes seven members: the retroviral proteins FBR-v-Fos and FBJ-v-Fos and the cellular proteins c-Fos, FosB, FosB2, Fra1, and Fra2. Four proteins (FBR-v-Fos, FBJ-v-Fos, c-Fos, and FosB) transform established rodent fibroblast cell lines, while three (FosB2, Fra1, and Fra2) do not. As all family members display sequence-specific DNA-binding activity as part of a heterodimeric complex with Jun proteins, other features must account for the differences in transforming potential. We demonstrate here that all transforming members have a C-terminal transactivation domain that is lacking in nontransforming members. The nontransforming proteins Fra1 and Fra2 can be converted to transforming proteins by fusion of a transactivation domain from either FosB or VP16. We also demonstrate that differences in the basic region-leucine zipper domain affecting either the affinity or sequence specificity of DNA binding are not determinants of the difference in transforming potential among members of the Fos family. The results further define the functional requirements for transformation by Fos proteins and suggest that the subunit composition of AP1 complexes is an important determinant of mitogenic signalling capability.

Down-regulation of nuclear aryl hydrocarbon receptor DNA-binding and transactivation functions: requirement for a labile or inducible factor

1994 ◽  
Vol 14 (9) ◽  
pp. 5653-5660
Author(s):  
M Reick ◽  
R W Robertson ◽  
D S Pasco ◽  
J B Fagan
Keyword(s):  
Dna Binding ◽  
Cell Line ◽  
Binding Activity ◽  
Ah Receptor ◽  
Down Regulation ◽  
Response Elements ◽  
Dna Binding Activity ◽  
Nuclear Extracts ◽  
Xenobiotic Response

Aryl hydrocarbons (AHs) such as 2,3,7,8-tetrachlorodibenzo-p-dioxin and benzo[a]pyrene activate the sequence-specific DNA-binding activity of the AH receptor. In the rat hepatocyte-derived cell line LCS7, DNA-binding activity peaked after 30 min and was then down-regulated, reaching negligible levels by 2 h. Down-regulation could be blocked, and DNA-binding activity maintained at maximum for many hours by inhibiting protein or RNA synthesis, implying that down-regulation is a mediated process requiring a labile or inducible protein. CYP1A1 transcription and in vivo DNA-protein interactions at xenobiotic response elements were down-regulated in parallel with DNA-binding activity in nuclear extracts, and these changes could also be blocked by inhibitors of protein synthesis. The correlation between AH receptor DNA-binding activity, intensity of in vivo footprints at xenobiotic response elements, and CYP1A1 transcription rate implies that down-regulation of AH receptor DNA-binding activity is important in regulating CYP1A1 transcription and that receptor is required continuously to maintain transcription. This correlation extends to the murine hepatoma cell line Hepa-1c1c7, in which slower kinetics of activation and down-regulation of CYP1A1 transcription paralleled slower activation and down-regulation of AH receptor DNA-binding activity. The difference in kinetics between cell lines also implies that AH receptor DNA-binding activity is modulated by a mechanism that may be influenced by cell-specific regulatory pathways. The above observations in conjunction with mixing experiments and comparisons of cytoplasmic and nuclear extracts indicate that down-regulation of AH receptor DNA-binding activity is probably due either to degradation or to conversion of the receptor to form that is inactive in both DNA binding and transactivation.

scholarly journals Transformation by Fos proteins requires a C-terminal transactivation domain.

1993 ◽  
Vol 13 (12) ◽  
pp. 7429-7438 ◽  
Author(s):  
R Wisdon ◽  
I M Verma
Keyword(s):  
Dna Binding ◽  
Leucine Zipper ◽  
Fibroblast Cell ◽  
Binding Activity ◽  
Sequence Specificity ◽  
Transactivation Domain ◽  
Functional Requirements ◽  
Dna Binding Activity ◽  
The Difference ◽  
Transforming Proteins

The Fos family of proteins now includes seven members: the retroviral proteins FBR-v-Fos and FBJ-v-Fos and the cellular proteins c-Fos, FosB, FosB2, Fra1, and Fra2. Four proteins (FBR-v-Fos, FBJ-v-Fos, c-Fos, and FosB) transform established rodent fibroblast cell lines, while three (FosB2, Fra1, and Fra2) do not. As all family members display sequence-specific DNA-binding activity as part of a heterodimeric complex with Jun proteins, other features must account for the differences in transforming potential. We demonstrate here that all transforming members have a C-terminal transactivation domain that is lacking in nontransforming members. The nontransforming proteins Fra1 and Fra2 can be converted to transforming proteins by fusion of a transactivation domain from either FosB or VP16. We also demonstrate that differences in the basic region-leucine zipper domain affecting either the affinity or sequence specificity of DNA binding are not determinants of the difference in transforming potential among members of the Fos family. The results further define the functional requirements for transformation by Fos proteins and suggest that the subunit composition of AP1 complexes is an important determinant of mitogenic signalling capability.

scholarly journals Down-regulation of nuclear aryl hydrocarbon receptor DNA-binding and transactivation functions: requirement for a labile or inducible factor.

1994 ◽  
Vol 14 (9) ◽  
pp. 5653-5660 ◽  
Author(s):  
M Reick ◽  
R W Robertson ◽  
D S Pasco ◽  
J B Fagan
Keyword(s):  
Dna Binding ◽  
Cell Line ◽  
Binding Activity ◽  
Ah Receptor ◽  
Down Regulation ◽  
Response Elements ◽  
Dna Binding Activity ◽  
Nuclear Extracts ◽  
Xenobiotic Response

Aryl hydrocarbons (AHs) such as 2,3,7,8-tetrachlorodibenzo-p-dioxin and benzo[a]pyrene activate the sequence-specific DNA-binding activity of the AH receptor. In the rat hepatocyte-derived cell line LCS7, DNA-binding activity peaked after 30 min and was then down-regulated, reaching negligible levels by 2 h. Down-regulation could be blocked, and DNA-binding activity maintained at maximum for many hours by inhibiting protein or RNA synthesis, implying that down-regulation is a mediated process requiring a labile or inducible protein. CYP1A1 transcription and in vivo DNA-protein interactions at xenobiotic response elements were down-regulated in parallel with DNA-binding activity in nuclear extracts, and these changes could also be blocked by inhibitors of protein synthesis. The correlation between AH receptor DNA-binding activity, intensity of in vivo footprints at xenobiotic response elements, and CYP1A1 transcription rate implies that down-regulation of AH receptor DNA-binding activity is important in regulating CYP1A1 transcription and that receptor is required continuously to maintain transcription. This correlation extends to the murine hepatoma cell line Hepa-1c1c7, in which slower kinetics of activation and down-regulation of CYP1A1 transcription paralleled slower activation and down-regulation of AH receptor DNA-binding activity. The difference in kinetics between cell lines also implies that AH receptor DNA-binding activity is modulated by a mechanism that may be influenced by cell-specific regulatory pathways. The above observations in conjunction with mixing experiments and comparisons of cytoplasmic and nuclear extracts indicate that down-regulation of AH receptor DNA-binding activity is probably due either to degradation or to conversion of the receptor to form that is inactive in both DNA binding and transactivation.

scholarly journals ComE, a Competence Protein from Neisseria gonorrhoeae with DNA-Binding Activity

2001 ◽  
Vol 183 (10) ◽  
pp. 3160-3168 ◽  
Author(s):  
Inês Chen ◽  
Emil C. Gotschlich
Keyword(s):  
Dna Binding ◽  
Neisseria Gonorrhoeae ◽  
Single Copy ◽  
Binding Activity ◽  
Sequence Specificity ◽  
Dna Uptake ◽  
Exogenous Dna ◽  
Dna Binding Activity ◽  
Type Iv ◽  
Different Strains

ABSTRACT Neisseria gonorrhoeae is naturally able to take up exogenous DNA and undergo genetic transformation. This ability correlates with the presence of functional type IV pili, and uptake of DNA is dependent on the presence of a specific 10-bp sequence. Among the known competence factors in N. gonorrhoeae, none has been shown to interact with the incoming DNA. Here we describe ComE, a DNA-binding protein involved in neisserial competence. The genecomE was identified through similarity searches in the gonococcal genome sequence, using as the query ComEA, the DNA receptor in competent Bacillus subtilis. The gene comEis present in four identical copies in the genomes of both N. gonorrhoeae and Neisseria meningitidis, located downstream of each of the rRNA operons. Single-copy deletion ofcomE in N. gonorrhoeae did not have a measurable effect on competence, whereas serial deletions led to gradual decrease in transformation frequencies, reaching a 4 × 104-fold reduction when all copies were deleted. Transformation deficiency correlated with impaired ability to take up exogenous DNA; however, the mutants presented normal piliation and twitching motility phenotype. The product of comE has 99 amino acids, with a predicted signal peptide; by immunodetection, a 8-kDa protein corresponding to processed ComE was observed in different strains of N. gonorrhoeae and N. meningitidis. Recombinant His-tagged ComE showed DNA binding activity, without any detectable sequence specificity. Thus, we identified a novel gonococcal DNA-binding competence factor which is necessary for DNA uptake and does not affect pilus biogenesis or function.

scholarly journals The NF-kappa B-binding site mediates phorbol ester-inducible transcription in nonlymphoid cells.

1988 ◽  
Vol 8 (8) ◽  
pp. 3526-3531 ◽  
Author(s):  
B Nelsen ◽  
L Hellman ◽  
R Sen
Keyword(s):  
B Cells ◽  
Dna Binding ◽  
Binding Site ◽  
Plasma Cells ◽  
Regulatory Element ◽  
Binding Activity ◽  
Sequence Specificity ◽  
Nf Kappa B ◽  
Dna Binding Activity ◽  
Kinetics Of

The mouse immunoglobulin kappa light-chain enhancer can interact with at least three independent nuclear proteins. One of these proteins, NF-kappa B, is constitutively present only in nuclear extracts derived from B cells and plasma cells. A DNA-binding protein with the same sequence specificity (and therefore presumed to be NF-kappa B itself) can be induced in pre-B cells, T cells, and nonlymphoid cells by phorbol 12-acetate-13-myristate (PMA); however, it is not clear whether the induced factor can activate transcription in nonlymphoid cells as NF-kappa B does in B cells. In this paper we show that multimerization of a fragment of the mouse kappa enhancer that carried only the binding site for NF-kappa B behaved like a B-cell-specific regulatory element. Furthermore, this unit served to activate transcription in nonlymphoid cells after treatment with PMA (but not with cyclic AMP derivatives), and the kinetics of transcription activation correlated well with the kinetics of factor induction. Thus, the induced DNA-binding activity appeared to be functionally indistinguishable from that of NF-kappa B.

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