The fifth Datta Lecture. Structural similarities between the aspartate receptor of bacterial chemotaxis and the trp repressor of E. coli. Implications for transmembrane signaling.
A high resolution structure of the N-terminal ligand-binding domain of the aspartate receptor which mediates aspartate chemotaxis in Salmonella typhimurium has recently been reported. A least-squares superposition of the alpha-amino nitrogen, alpha-carbon, beta-carbon, and alpha-carboxylate carbon of the aspartate bound to the aspartate receptor onto the equivalent atoms in the tryptophan bound to the trp repressor provides evidence for similarity between key parts of the active sites that bind to the alpha-amino and alpha-carboxylates of the respective ligands. Because the N-terminal domain of the aspartate receptor and the trp repressor also share other structural similarities, we hypothesize that the similarity between the aspartate receptor and the trp repressor derives from a similarity in ligand-induced conformational changes at the active sites of these proteins. This hypothesis also implies that an important signaling event in the aspartate receptor occurs through tertiary conformational changes within a single subunit.
Lynch
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BA
Department of Molecular and Cell Biology, University of California, Berkeley 94720.
Koshland
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DE
D001224:Aspartic Acid / Q000378:metabolism*; D001426:Bacterial Proteins; D001665:Binding Sites; D002633:Chemotaxis; D004926:Escherichia coli / Q000378:metabolism*; D011487:Protein Conformation; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism*; D029968:Escherichia coli Proteins
D001224:Aspartic Acid; D001426:Bacterial Proteins; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface; D012097:Repressor Proteins; D014364:Tryptophan; C027190:TRPR protein, E coli; D029968:Escherichia coli Proteins; C031959:aspartic acid receptor