PMID:12437376
| Citation |
Salopek-Sondi, B, Swartz, D, Adams, PS and Luck, LA (2002) Exploring the role of amino acid-18 of the leucine binding proteins of E. coli. J. Biomol. Struct. Dyn. 20:381-7 |
|---|---|
| Abstract |
Two periplasmic binding proteins of E. coli, the leucine specific-binding protein (LS) and leucine-isoleucine-valine binding protein (LIV), have high similarity in their structure and function, but show different substrate specificity. A key difference between these proteins is residue 18 in the binding pocket, a tryptophan residue in the LS and a tyrosine residue in the LIV. To examine the role of this residue in binding specificity, we used fluorescence and (19)F NMR to monitor ligand binding to three mutants: LSW18Y, LSW18F and LIVY18W. We observed leucine binding to all proteins. LS binds L-phenylalanine but the mutation from Trp to Tyr or Phe disallows this ligand and expands the binding repertoire to L-isoleucine and L-valine. The LIVY18W mutant still retains the ability to bind L-isoleucine and also binds L-phenylalanine. |
| Links |
PubMed Online version:10.1080/07391102.2002.10506856 |
| Keywords |
Amino Acid Sequence; Amino Acids, Branched-Chain/metabolism; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Crystallography, X-Ray; Escherichia coli/genetics; Escherichia coli/metabolism; Genes, Bacterial; Leucine/metabolism; Ligands; Membrane Proteins/genetics; Membrane Proteins/metabolism; Models, Molecular; Mutagenesis, Site-Directed; Nuclear Magnetic Resonance, Biomolecular; Point Mutation; Protein Conformation; Protein Denaturation; Protein Structure, Tertiary; Structure-Activity Relationship; Substrate Specificity; Tryptophan/metabolism; Urea |
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