Structural highlights
Function
[BIRA_ECOLI] Acts both as a biotin--[acetyl-CoA-carboxylase] ligase and a biotin-operon repressor. In the presence of ATP, BirA activates biotin to form the BirA-biotinyl-5'-adenylate (BirA-bio-5'-AMP or holoBirA) complex. HoloBirA can either transfer the biotinyl moiety to the biotin carboxyl carrier protein (BCCP) subunit of acetyl-CoA carboxylase, or bind to the biotin operator site and inhibit transcription of the operon.[1] [2] [3] [4]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
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.
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[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Eisenberg MA, Prakash O, Hsiung SC. Purification and properties of the biotin repressor. A bifunctional protein. J Biol Chem. 1982 Dec 25;257(24):15167-73. PMID:6129246
- ↑ Cronan JE Jr. The E. coli bio operon: transcriptional repression by an essential protein modification enzyme. Cell. 1989 Aug 11;58(3):427-9. PMID:2667763
- ↑ Xu Y, Beckett D. Kinetics of biotinyl-5'-adenylate synthesis catalyzed by the Escherichia coli repressor of biotin biosynthesis and the stability of the enzyme-product complex. Biochemistry. 1994 Jun 14;33(23):7354-60. PMID:8003500
- ↑ Streaker ED, Beckett D. Coupling of protein assembly and DNA binding: biotin repressor dimerization precedes biotin operator binding. J Mol Biol. 2003 Jan 31;325(5):937-48. PMID:12527300 doi:http://dx.doi.org/10.1016/S0022283602013086
- ↑ Wilson KP, Shewchuk LM, Brennan RG, Otsuka AJ, Matthews BW. Escherichia coli biotin holoenzyme synthetase/bio repressor crystal structure delineates the biotin- and DNA-binding domains. Proc Natl Acad Sci U S A. 1992 Oct 1;89(19):9257-61. PMID:1409631
