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Review
. 2007 Dec;19(12):3843-51.
doi: 10.1105/tpc.107.055053. Epub 2007 Dec 14.

Exploring the molecular etiology of dominant-negative mutations

Reiner A Veitia  1
Affiliations
Review

Exploring the molecular etiology of dominant-negative mutations

Reiner A Veitia. Plant Cell. 2007 Dec.
No abstract available

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Figures

Figure 1.
Figure 1.
A Typical Example of a DN Mutation. Signal transduction system involving a dimeric receptor whose cytoplasmic portion contains a PK domain. Upon interaction with an extracellular ligand, the PK activity of one monomer phosphorylates the cytoplasmic side of the other monomer. If a mutant monomer lacks the cytoplasmic portion, only 25% of the dimeric receptor will work properly, which in most cases is not enough to elicit a normal response.
Figure 2.
Figure 2.
DNE Mutations Can Also Appear in Homodimeric Ligands. (A) Wild-type case. The dimer AA interacts with the receptor with two times more energy than Aa. This translates into a huge difference in terms of affinities (see Supplemental Materials online). (B) Coexpression (equimolar amounts) of a wild-type and a DN subunit unable to interact with the receptor. (C) Sequential interaction between a ligand and its receptor (here, a piece of DNA or RNA with two binding sites). The dimer is formed during DNA/RNA binding. The first monomer interacts with DNA (RNA) with an energy E1, and the newcomer monomer is attracted by both the first monomer sitting on its binding site (E2) and by the nearing free binding site (E1). In sum, the newcomer monomer is attracted more strongly than the first one (with E1+E2). This is a source of cooperativity. The triangle represents a DN protein.
Figure 3.
Figure 3.
Binding Curves for a Dimer AA (Aa or aa) Interacting with a Target RR. To display the responses of different genotypes on the same graph, Y is represented as a function of protein concentration (A or a) relative to an arbitrary maximal output for each genotype (range between 0 and 1). Of course, the concentrations of A (or a) and of dimers is a function of the strength or duration of a signal. In absolute terms, for any value of x (which depends directly on the intensity of the stimulus), A/- will have two times less monomers and dimers than A/A. As expected, the curve for A/- (light blue) is always lower than that of A/A (dark blue). The position of the curve for A/a, where a exerts a DNE, depends on the residual activity of a. (A) The monomer a has kept only 1/100 of the intrinsic binding activity of a normal monomer (i.e., almost no binding of aa). It behaves as a canonical DN protein (red curve) and overexpression of a (2× and 5×) with respect to A leads to a consistent decrease in total binding activity (gray and black curves, respectively). When a has lost its activity, binding of Aa or aa is virtually negligible. (B) The monomer a has kept approximately one-third of the intrinsic binding activity of A. The hypomorphic character of a is obvious from the inspection of the curve a/a (i.e., there is binding). However, the curves of A/- and A/a almost coincide, which means that in the heterozygote, a behaves apparently as a null allele. This is explained by a subtle DNE. Overexpression of a leads to paradoxical results.
Figure 4.
Figure 4.
Trans-DNEs Due to Overexpression. (A) Irreversible assembly of trimer A-B-A allowing intermediate dimers AB and BA (represented). (B) An excess of the molecular bridge B (1.5×) leads to a dramatic decrease in yield of ABA due to the production of intermediates that cannot be completed because of the lack of enough A monomers.
Figure 5.
Figure 5.
Other Trans-DNEs. (A) Monomers A and B can form homo- and heterodimers. (B) Overexpression of A alters the ratio between the different dimers. (C) Introduction of a strong DN mutant a leads to the production of a substantial amount of nonfunctional dimers (Aa, aa, aB, etc.).
Figure 6.
Figure 6.
DNEs in Transcription. (A) Promoter with two binding sites (gray triangles) recognized in a cooperative fashion by the activator A or its truncated form a, which behaves as a competitive inhibitor. (B) Cooperativity may be due to the concerted attraction of an incoming monomer by A sitting on the DNA and a neighboring DNA site. (C) Synergy: two monomers sitting on their DNA binding sites will attract the polymerase (pol) much more strongly than only one monomer bound to DNA. Synergy is disrupted when a monomer lacks the polymerase recruiting domain.
Figure 7.
Figure 7.
TR of a Promoter (with Two Sites) to the Activator A Alone or Coexpressed (in Equimolar Amounts) with Its DN Form a. The graph represents TR as a function of the per allele production of A (a) relative to a maximal output. The output in terms of concentrations of A (a) depends directly on the strength (duration) of a signal that drives the production of A (a). In the particular case of the heterozygote A/-, for any value of x, it will have two times less A protein than A/A. Thus, the values of TR for the heterozygote A/- at any point (light blue) are lower than in the normal A/A (dark blue), but for high values of A, saturation is reached. In A/a when a lacks the transactivation capacity in absence of cooperativity between A and a, there is a tendency to reach saturation with increasing concentrations of A and a, as the former tends to occupy the promoter by cooperatively recruiting other molecules of A (pink). When cooperativity between A and a is maintained, the plateau of the curve for A/a is reached at TR = 0.25 (green) as the transcriptionally active species pAA represents only 25% of the total. When there is residual transactivation and cooperativity is normal, the plateau in A/a is not reached at TR = 1 but at a lower level (red). Consequently, the curve for A/a crosses that of A/-. This allele a is hypomorphic if the system normally works at low saturation levels of A and a, while it is DN for higher concentrations. Parameters are in the Supplemental Materials online.
Figure 8.
Figure 8.
Response of Two Different Artificial Promoters (p) Containing One or Two Bicoid-Like Binding Sites for TF PITX2a and Its DN Version (K88E). Solid lines: promoter activity (luciferase reporter system) in the presence of the wild-type TF. Dotted lines: coexpression of the wild type and its DN version. Notice how at low amounts of transfecting DNA, the response of the promoter with two sites is >2 times stronger (i.e., 3×) than the response of the promoter with only one site due to cooperativity and synergy. As predicted, at high amounts of constructs WT+DN, the TR of the promoter with two binding sites is ∼25% of response of the wild type alone. The drop in TR is, as expected, less dramatic for the promoter with only one binding site. Reproduced and modified with permission of the authors and from Molecular and Cellular Biology and the American Society for Microbiology (Saadi et al., 2003).
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References

    1. Adams, K.L., Cronn, R., Percifield, R., and Wendel, J.F. (2003). Genes duplicated by polyploidy show unequal contributions to the transcriptome and organ-specific reciprocal silencing. Proc. Natl. Acad. Sci. USA 100 4649–4654. - PMC - PubMed
    1. Barren, B., and Artemyev, N.O. (2007). Mechanisms of dominant negative G-protein alpha subunits. J. Neurosci. Res. 85 3505–3514. - PubMed
    1. Birchler, J.A., Bhadra, U., Bhadra, M.P., and Auger, D.L. (2001). Dosage-dependent gene regulation in multicellular eukaryotes: implications for dosage compensation, aneuploid syndromes, and quantitative traits. Dev. Biol. 234 275–288. - PubMed
    1. Burz, D.S., and Hanes, S.D. (2001). Isolation of mutations that disrupt cooperative DNA binding by the Drosophila bicoid protein. J. Mol. Biol. 305 219–230. - PubMed
    1. Carey, M. (1998). The enhanceosome and transcriptional synergy. Cell 92 5–8. - PubMed

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