Escherichia coli aspartate transcarbamoylase: the molecular basis for a concerted allosteric transition.
Aspartate transcarbamoylase from Escherichia coli has become a model system for the study of both homotropic and heterotropic interactions in proteins. Analysis of the X-ray structures of the enzyme in the absence and presence of substrates and substrate analogs has revealed sets of interactions that appear to stabilize either the 'T' or the 'R' states of the enzyme. Site-specific mutagenesis has been used to test which of these interactions are functionally important. By combining the structural data from X-ray crystallography, and the functional data from site-specific mutagenesis a model is proposed for homotropic cooperativity in aspartate transcarbamoylase that suggests that the allosteric transition occurs in a concerted fashion.
Department of Chemistry, Boston College, Chestnut Hill, MA 02167.
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Kantrowitz
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Lipscomb
D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D001221:Aspartate Carbamoyltransferase / Q000378:metabolism*; D001665:Binding Sites; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology*; D008969:Molecular Sequence Data
D001221:Aspartate Carbamoyltransferase