Site-directed mutagenesis of the lipoate acetyltransferase of Escherichia coli.
Remote but significant similarities between the primary and predicted secondary structures of the chloramphenicol acetyltransferases (CAT) and lipoate acyltransferase subunits (LAT, E2) of the 2-oxo acid dehydrogenase complexes, have suggested that both types of enzyme may use similar catalytic mechanisms. Multiple sequence alignments for CAT and LAT have highlighted two conserved motifs that contain the active-site histidine and serine residues of CAT. Site-directed replacement of Ser550 in the E2p subunit (LAT) of the pyruvate dehydrogenase complex of Escherichia coli, deemed to be equivalent to the active-site Ser148 of CAT, supported the CAT-based model of LAT catalysis. The effects of other substitutions were also consistent with the predicted similarity in catalytic mechanism although specific details of active-site geometry may not be conserved.
Krebs Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, U.K.
G C
GC
Russell
J R
JR
Guest
D000123:Acetyltransferases / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D051047:Dihydrolipoyllysine-Residue Acetyltransferase; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D015345:Oligonucleotide Probes; D009876:Operon; D010957:Plasmids; D011487:Protein Conformation; D011768:Pyruvate Dehydrogenase Complex
D046911:Macromolecular Substances; D015345:Oligonucleotide Probes; D011768:Pyruvate Dehydrogenase Complex; D000123:Acetyltransferases; D051047:Dihydrolipoyllysine-Residue Acetyltransferase; D015500:Chloramphenicol O-Acetyltransferase