OhrR: Difference between revisions

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OhrR plays a critical role in sensing of reactive oxygen species in the pathogenic bacteria Xanthomonas campestris. Under normal cellular conditions, dimeric OhrR protein is bound to DNA to repress expression of ohr, which encodes organic hydroperoxide resistance protein. When the reactive oxygen species organic hydroperoxide (OHR) is present in the cell, it oxidizes a reactive cysteine in OhrR, resulting in a conformational change that causes the dissocation of OhrR from ohr and subsequent clearance of OHR by OHR. This dissociation occurs because the oxidation of this reactive cysteine results in the formation of an interprotein cysteine bond between each of two units.

~~<scene name='User:David_Bruhn/Sandbox1/Pasted_morph/1'>TextToBeDisplayed</scene>~~

==Crystallization and Quality of OhrR ''Xc'' Models==

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==Structure of Reduced OhrR ''Xc''==

The resulting model 2pex shows the biologically relevant dimer of the protein. Each subunit of the dimer is composed of six α-helices and 3 β-strands.

The specific residues corresponding to these regions of secondary structure are as follows.

1. α1 (residues 21–39)

2. α2 (residues 47–58),

3. β1(residues 62–63),

4. α3 (residues 64–71),

5. α4 (residues 75–87),

6. β2 (residues 91–94),

7. β3 (residues 104–107),

8. α5 (residues109–129),

a. longest helix

b. displays a kink that is centered about residue G119.

9. α6 (residues 133–151)

10. two single-turn 310 helices N-terminal to helix α1:

a. 1a (residues 13–15)

b. 1b (residues 17–19).

The winged-HTH DNA-binding motif

- Formed by helices α3 and α4 followed by β strands β2 and β3, which form a small β sheet with β1.

-

Interface

- 310 Helices (1a, 1b) α1, α5, and α6 from each subunit form an extensive dimerization interface that buries a surface area of 5391 Å2

Connecting HTH and OHP sensing domains

- Helices α2 and α5 lie perpendicular to each other across one face of each subunit and act to connect the dimerization and OHP sensing domains to the winged-HTH motifs (Figure 1A).

**.

The extensive dimerization domain buries 5391Å².

~~generate applet highlighting the views in potential video for this structure.~~

==Oxidation-induced Confirmational Changes in OhrR Xc==

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 OhrR plays a critical role in sensing of reactive oxygen species in the pathogenic bacteria Xanthomonas campestris. Under normal cellular conditions, dimeric OhrR protein is bound to DNA to repress expression of ohr, which encodes organic hydroperoxide resistance protein. When the reactive oxygen species organic hydroperoxide (OHR) is present in the cell, it oxidizes a reactive cysteine in OhrR, resulting in a conformational change that causes the dissocation of OhrR from ohr and subsequent clearance of OHR by OHR. This dissociation occurs because the oxidation of this reactive cysteine results in the formation of an interprotein cysteine bond between each of two units.
-<scene name='User:David_Bruhn/Sandbox1/Pasted_morph/1'>TextToBeDisplayed</scene>
 ==Crystallization and Quality of OhrR ''Xc'' Models==
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 ==Structure of Reduced OhrR ''Xc''==
+The resulting model 2pex shows the biologically relevant dimer of the protein. Each subunit of the dimer is composed of six α-helices and 3 β-strands.
+The specific residues corresponding to these regions of secondary structure are as follows.
+.	α1 (residues 21–39)
+.	 α2 (residues 47–58),
+.	 β1(residues 62–63),
+.	α3 (residues 64–71),
+.	α4 (residues 75–87),
+.	β2 (residues 91–94),
+.	β3 (residues 104–107),
+.	α5 (residues109–129),
+a.	longest helix
+b.	displays a kink that is centered about residue G119.
+.	α6 (residues 133–151)
+.	two single-turn 310 helices N-terminal to helix α1:
+a.	1a (residues 13–15)
+b.	1b (residues 17–19).
+The winged-HTH DNA-binding motif
+-	Formed by helices α3 and α4 followed by β strands β2 and β3, which form a small β sheet with β1.
+-
+Interface
+-	310 Helices (1a, 1b) α1, α5, and α6 from each subunit form an extensive dimerization interface that buries a surface area of 5391 Å2
+Connecting HTH and OHP sensing domains
+-	Helices α2 and α5 lie perpendicular to each other across one face of each subunit and act to connect the dimerization and OHP sensing domains to the winged-HTH motifs (Figure 1A).
+**.
+The extensive dimerization domain buries 5391Å².
-generate applet highlighting the views in potential video for this structure.
 ==Oxidation-induced Confirmational Changes in OhrR Xc==