From Proteopedia
(Difference between revisions)
proteopedia linkproteopedia link
|
|
| Line 1: |
Line 1: |
| - | [[Image:1bjy.jpg|left|200px]] | + | {{Seed}} |
| | + | [[Image:1bjy.png|left|200px]] |
| | | | |
| | <!-- | | <!-- |
| Line 9: |
Line 10: |
| | {{STRUCTURE_1bjy| PDB=1bjy | SCENE= }} | | {{STRUCTURE_1bjy| PDB=1bjy | SCENE= }} |
| | | | |
| - | '''TETRACYCLINE CHELATED MG2+-ION INITIATES HELIX UNWINDING FOR TET REPRESSOR INDUCTION'''
| + | ===TETRACYCLINE CHELATED MG2+-ION INITIATES HELIX UNWINDING FOR TET REPRESSOR INDUCTION=== |
| | | | |
| | | | |
| - | ==Overview==
| + | <!-- |
| - | The homodimeric tetracycline repressor (TetR) regulates resistance to the antibiotic tetracycline at the transcriptional level. TetR binds in the absence of Tc to palindromic operator sequences utilizing two helix-turn-helix (HTH) motifs. If the tetracycline-Mg2+ complex [MgTc]+ enters two identical binding tunnels buried within the TetR homodimer, a conformational change takes place, and the induced [TetR/[MgTc]+]2 complex releases operator DNA. To demonstrate the contribution of Mg2+ to [MgTc]+ binding and TetR induction, the Mg2+ concentration in the induced TetR homodimer was progressively reduced by addition of EDTA, resulting in two X-ray crystal structures of Mg2+-free and half-occupied TetR(D). Tc remains bound to the [MgTc]+-binding sites, despite the complete or partial absence of Mg2+. Together with inducer-free TetR(D), the structures were refined to between 2.2 and 2.7 A resolution and compared with fully induced TetR(D) in complex with two [MgTc]+. Each inducer binding tunnel has three constituent parts, one hydrophobic and two hydrophilic ones. One of the hydrophilic contact areas binds Tc by hydrogen bonding; the hydrophobic region correctly positions Tc and partially closes the entrance to the binding tunnel; the second hydrophilic region coordinates Mg2+, transduces the induction signal, and completes the process of closing the tunnel entrance. Tc confers binding specificity to TetR while Mg2+ is primarily responsible for induction: After binding to the imidazole Nepsilon of His100, Mg2+ is octahedrally coordinated to the 1,3-ketoenolate group of Tc and to three water molecules. One of these waters forms a hydrogen bond to the hydroxyl group Ogamma of Thr103. The induced 2.5 A movement of Thr103 results in the partial unwinding of helix alpha6, associated with a lateral shift of helices alpha4 and alpha9. They simultaneously close the tunnel entrance and cause the DNA-binding domains to adopt a nonbinding conformation, leading to release of operator DNA and expression of the genes responsible for resistance. | + | The line below this paragraph, {{ABSTRACT_PUBMED_9890898}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 9890898 is the PubMed ID number. |
| | + | --> |
| | + | {{ABSTRACT_PUBMED_9890898}} |
| | | | |
| | ==About this Structure== | | ==About this Structure== |
| Line 28: |
Line 32: |
| | [[Category: Hth-motif]] | | [[Category: Hth-motif]] |
| | [[Category: Transcription regulation]] | | [[Category: Transcription regulation]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 11:36:45 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 19:17:03 2008'' |
Revision as of 16:17, 30 June 2008
Template:STRUCTURE 1bjy
TETRACYCLINE CHELATED MG2+-ION INITIATES HELIX UNWINDING FOR TET REPRESSOR INDUCTION
Template:ABSTRACT PUBMED 9890898
About this Structure
1BJY is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Tetracycline-chelated Mg2+ ion initiates helix unwinding in Tet repressor induction., Orth P, Saenger W, Hinrichs W, Biochemistry. 1999 Jan 5;38(1):191-8. PMID:9890898
Page seeded by OCA on Mon Jun 30 19:17:03 2008
