1bib
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(New page: 200px<br /><applet load="1bib" size="450" color="white" frame="true" align="right" spinBox="true" caption="1bib, resolution 2.8Å" /> '''THE E. COLI BIOTIN HO...) |
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caption="1bib, resolution 2.8Å" /> | caption="1bib, resolution 2.8Å" /> | ||
'''THE E. COLI BIOTIN HOLOENZYME SYNTHETASE(SLASH)BIO REPRESSOR CRYSTAL STRUCTURE DELINEATES THE BIOTIN AND DNA-BINDING DOMAINS'''<br /> | '''THE E. COLI BIOTIN HOLOENZYME SYNTHETASE(SLASH)BIO REPRESSOR CRYSTAL STRUCTURE DELINEATES THE BIOTIN AND DNA-BINDING DOMAINS'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The three-dimensional structure of BirA, the repressor of the Escherichia | + | The three-dimensional structure of BirA, the repressor of the Escherichia coli biotin biosynthetic operon, has been determined by x-ray crystallography and refined to a crystallographic residual of 19.0% at 2.3-A resolution. BirA is a sequence-specific DNA-binding protein that also catalyzes the formation of biotinyl-5'-adenylate from biotin and ATP and transfers the biotin moiety to other proteins. The level of biotin biosynthetic enzymes in the cell is controlled by the amount of biotinyl-5'-adenylate, which is the BirA corepressor. The structure provides an example of a transcription factor that is also an enzyme. The structure of BirA is highly asymmetric and consists of three domains. The N-terminal domain is mostly alpha-helical, contains a helix-turn-helix DNA-binding motif, and is loosely connected to the remainder of the molecule. The central domain consists of a seven-stranded mixed beta-sheet with alpha-helices covering one face. The other side of the sheet is largely solvent-exposed and contains the active site. The C-terminal domain comprises a six-stranded, antiparallel beta-sheet sandwich. The location of biotin binding is consistent with mutations that affect enzymatic activity. A nearby loop has a sequence that has been associated with phosphate binding in other proteins. It is inferred that ATP binds in this region, adjacent to the biotin. It is proposed that the binding of corepressor to monomeric BirA may promote DNA binding by facilitating the formation of a multimeric BirA-corepressor-DNA complex. The structural details of this complex remain an open question, however. |
==About this Structure== | ==About this Structure== | ||
| - | 1BIB is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with BTN as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Biotin--[acetyl-CoA-carboxylase]_ligase Biotin--[acetyl-CoA-carboxylase] ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.4.15 6.3.4.15] Full crystallographic information is available from [http:// | + | 1BIB is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=BTN:'>BTN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Biotin--[acetyl-CoA-carboxylase]_ligase Biotin--[acetyl-CoA-carboxylase] ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.4.15 6.3.4.15] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1BIB OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Matthews, B | + | [[Category: Matthews, B W.]] |
| - | [[Category: Shewchuk, L | + | [[Category: Shewchuk, L M.]] |
| - | [[Category: Wilson, K | + | [[Category: Wilson, K P.]] |
[[Category: BTN]] | [[Category: BTN]] | ||
[[Category: transcription regulation]] | [[Category: transcription regulation]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:55:37 2008'' |
Revision as of 09:55, 21 February 2008
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THE E. COLI BIOTIN HOLOENZYME SYNTHETASE(SLASH)BIO REPRESSOR CRYSTAL STRUCTURE DELINEATES THE BIOTIN AND DNA-BINDING DOMAINS
Overview
The three-dimensional structure of BirA, the repressor of the Escherichia coli biotin biosynthetic operon, has been determined by x-ray crystallography and refined to a crystallographic residual of 19.0% at 2.3-A resolution. BirA is a sequence-specific DNA-binding protein that also catalyzes the formation of biotinyl-5'-adenylate from biotin and ATP and transfers the biotin moiety to other proteins. The level of biotin biosynthetic enzymes in the cell is controlled by the amount of biotinyl-5'-adenylate, which is the BirA corepressor. The structure provides an example of a transcription factor that is also an enzyme. The structure of BirA is highly asymmetric and consists of three domains. The N-terminal domain is mostly alpha-helical, contains a helix-turn-helix DNA-binding motif, and is loosely connected to the remainder of the molecule. The central domain consists of a seven-stranded mixed beta-sheet with alpha-helices covering one face. The other side of the sheet is largely solvent-exposed and contains the active site. The C-terminal domain comprises a six-stranded, antiparallel beta-sheet sandwich. The location of biotin binding is consistent with mutations that affect enzymatic activity. A nearby loop has a sequence that has been associated with phosphate binding in other proteins. It is inferred that ATP binds in this region, adjacent to the biotin. It is proposed that the binding of corepressor to monomeric BirA may promote DNA binding by facilitating the formation of a multimeric BirA-corepressor-DNA complex. The structural details of this complex remain an open question, however.
About this Structure
1BIB is a Single protein structure of sequence from Escherichia coli with as ligand. Active as [acetyl-CoA-carboxylase_ligase Biotin--[acetyl-CoA-carboxylase] ligase], with EC number 6.3.4.15 Full crystallographic information is available from OCA.
Reference
Escherichia coli biotin holoenzyme synthetase/bio repressor crystal structure delineates the biotin- and DNA-binding domains., Wilson KP, Shewchuk LM, Brennan RG, Otsuka AJ, Matthews BW, Proc Natl Acad Sci U S A. 1992 Oct 1;89(19):9257-61. PMID:1409631 [[Category: Biotin--[acetyl-CoA-carboxylase] ligase]]
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