1. Biotinylation in the hyperthermophile Aquifex aeolicus.
- Author
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Clarke DJ, Coulson J, Baillie R, and Campopiano DJ
- Subjects
- Acetyl-CoA Carboxylase genetics, Acetyl-CoA Carboxylase metabolism, Amino Acid Sequence, Bacterial Proteins genetics, Bacterial Proteins isolation & purification, Biotin metabolism, Biotinylation, Carbon-Nitrogen Ligases genetics, Carbon-Nitrogen Ligases isolation & purification, Carrier Proteins genetics, Carrier Proteins metabolism, Cloning, Molecular, Cross-Linking Reagents metabolism, Escherichia coli Proteins genetics, Escherichia coli Proteins isolation & purification, Fatty Acid Synthase, Type II, Molecular Sequence Data, Protein Binding, Recombinant Proteins genetics, Recombinant Proteins metabolism, Repressor Proteins genetics, Repressor Proteins isolation & purification, Sequence Alignment, Transcription Factors genetics, Transcription Factors isolation & purification, Bacteria enzymology, Bacterial Proteins metabolism, Carbon-Nitrogen Ligases metabolism, Escherichia coli Proteins metabolism, Repressor Proteins metabolism, Transcription Factors metabolism
- Abstract
Biotin protein ligase (BPL) catalyses the biotinylation of the biotin carboxyl carrier protein (BCCP) subunit of acetyl CoA carboxylase and this post-translational modification of a single lysine residue is exceptionally specific. The exact details of the protein-protein interactions involved are unclear as a BPL:BCCP complex has not yet been isolated. Moreover, detailed information is lacking on the composition, biosynthesis and role of fatty acids in hyperthermophilic organisms. We have cloned, overexpressed and purified recombinant BPL and the biotinyl domain of BCCP (BCCP Delta 67) from the extreme hyperthermophile Aquifex aeolicus. In vitro assays have demonstrated that BPL catalyses biotinylation of lysine 117 on BCCP Delta 67 at temperatures of up to 70 degrees C. Limited proteolysis of BPL with trypsin and chymotrypsin revealed a single protease-sensitive site located 44 residues from the N-terminus. This site is adjacent to the predicted substrate-binding site and proteolysis of BPL is significantly reduced in the presence of MgATP and biotin. Chemical crosslinking with 1-ethyl-3-(dimethylamino-propyl)-carbodiimide (EDC) allowed the isolation of a BPL:apo-BCCP Delta 67 complex. Furthermore, this complex was also formed between BPL and a BCCP Delta 67 mutant lacking the lysine residue (BCCP Delta 67 K117L) however, complex formation was considerably reduced using holo-BCCP Delta 67. These observations provide evidence that addition of the biotin prosthetic group reduces the ability of BCCP Delta 67 to heterodimerize with BPL, and emphasizes that a network of interactions between residues on both proteins mediates protein recognition.
- Published
- 2003
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