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Results: 9

1.
Figure 6

Figure 6. From: GalR mutants defective in repressosome formation.

Far-UV CD spectra of GalR wild type (●) and GalR mutant D258N (×) (A), and GalR wild type (●) and GalR mutant R325H (+) (B).

Mark Geanacopoulos, et al. Genes Dev. 1999 May 15;13(10):1251-1262.
2.
Figure 8

Figure 8. From: GalR mutants defective in repressosome formation.

Effect of the site-directed chromosomal galR mutations N259M (●), T322R (⋄), and H327R (♦) on looping-dependent repression of galP2 (a) and independent repression of galP1 (b) compared with that obtained in wild-type (○) and galR deletion (⋄) strains.

Mark Geanacopoulos, et al. Genes Dev. 1999 May 15;13(10):1251-1262.
3.

Figure 9. From: GalR mutants defective in repressosome formation.

Construction of the dual reporter strain. (A) Transfer of the galP1-lacZ fusion to the chromosome by homologous recombination. (B) Construction of a second reporter fusion by homologous recombination and integration into the bacterial chromosome at the λ att site. Details are given in Materials and Methods.

Mark Geanacopoulos, et al. Genes Dev. 1999 May 15;13(10):1251-1262.
4.
Figure 1

Figure 1. From: GalR mutants defective in repressosome formation.

(A) Map of the gal promoter region showing the location of the P1 and P2 promoters, the tandem gal operators, and the center of the HU-binding site hbs. (B) Schematic drawing of the OE+P2P1+galE–lacZ and OE+P2+P1galEOI+–gusA fusions. The latter is present as a lysogen.

Mark Geanacopoulos, et al. Genes Dev. 1999 May 15;13(10):1251-1262.
5.
Figure 4

Figure 4. From: GalR mutants defective in repressosome formation.

Transcription of galP1 and galP2 promoters on the supercoiled template pSA509 in the presence of wild-type GalR and GalR mutants E230K, D258N, and R325H. (Top) Titration with GalR proteins in the absence of HU or HMG-17; (middle, bottom the same reactions in the presence of 80 nm HU dimer or 500 nm HMG-17 (monomer), respectively. The 80-bp RNA 1 transcripts, which do not vary as a function of GalR concentration, served as an internal control between lanes.

Mark Geanacopoulos, et al. Genes Dev. 1999 May 15;13(10):1251-1262.
6.

Figure 3. From: GalR mutants defective in repressosome formation.

Effect of GalR mutations E230K, D258N, and R325H on looping-dependent repression of galP2 (a) and looping-independent repression of galP1 (b). galR+ (○), galR D258N (●), galR E230K (⋄), galR R325H (♦), and ΔgalR (○) strains were grown in minimal medium and assayed for expression of the P2–gusA fusion containing both operators (a) and the galP1–lacZ fusion containing only OE (b). β-Galactosidase and β-glucuronidase activities are expressed as the change in optical density/min during enzyme assay. (c,d) Expression of the gusA and lacZ reporter genes when the same set of galR alleles were expressed from a multicopy plasmid vector in a host deleted for galR.

Mark Geanacopoulos, et al. Genes Dev. 1999 May 15;13(10):1251-1262.
7.

Figure 5. From: GalR mutants defective in repressosome formation.

Regulation of the galP1(a,c,e) and galP2 (b,d,f) promoters in the absence of cofactors (a,b) or in the presence of HU (c,d) or HMG-17 (e,f) by wild-type GalR (black), or GalR mutants E230K (green), D258N (blue), or R325H (red). RNA from gels in Fig. 4 was quantified with a PhosphorImager, and transcription is expressed as the fraction of that which was obtained in the absence of the repressor protein. Repression data for P1 and for P2 with wild-type GalR in the presence of HU or HMG-17 were fitted to the function 1/(1 + Kx) in which x is the concentration of the repressor and K is an apparent association constant. All other data were fitted to a second-order polynomial.

Mark Geanacopoulos, et al. Genes Dev. 1999 May 15;13(10):1251-1262.
8.
Figure 2

Figure 2. From: GalR mutants defective in repressosome formation.

Effect of gal promoter mutations on in vivo transcription at P1 and P2 promoters. Primer extension of gal-specific DNA was performed in strain DM0013 containing the wild-type gal promoter (lanes 3,4), DM0012 in which the gal promoter contains a G-to-T transversion at position −19 (lanes 5,6), or DM0011 containing a G-to-A transition at −14 (lanes 7,8). Cells were grown in the absence (lanes 3,5,7) or presence (lanes 4,6,8) of the inducer d-galactose. (Lane 1) Phosphorylated DNA standards; (lane 2) expected 87-base primer-extension product from a control reaction with a specific primer with homogeneous RNA.

Mark Geanacopoulos, et al. Genes Dev. 1999 May 15;13(10):1251-1262.
9.
Figure 7

Figure 7. From: GalR mutants defective in repressosome formation.

Model of the GalR dimer showing the location of mutations affecting repressosome formation in GalR. The dimeric of the GalR core (above the gray line) was modeled by homologous extension with the PurR and LacI structures. The DNA-binding domain and DNA from the PurR X-ray structure (Schumacher et al. 1994) are shown (below gray line) for reference. The β-carbon positions of the amino acids identified in our screening are shown in red. The location of the site-directed mutations, which specifically disrupted looping-mediated repression, are shown in orange. Shown in green are the α carbons of the nonconservative site-directed substitutions that had no effect on looping-mediated repression. Note that because the structure has C2 symmetry, the same arrangement of residues (not highlighted) occurs on the opposite face of the molecule. Carboxy-terminal residues 329–343, which could not be modeled by homologous extension and whose deletion did not have a marked effect on repression, are not shown.

Mark Geanacopoulos, et al. Genes Dev. 1999 May 15;13(10):1251-1262.

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