Mutagenesis of arginine residues in the catalytic cleft of Escherichia coli porphobilinogen deaminase that affects dipyrromethane cofactor assembly and tetrapyrrole chain initiation and elongation.
Substitutions of conserved arginine residues in the catalytic cleft of Escherichia coli porphobilinogen deaminase were constructed by site-specific mutagenesis of the hemC gene. Mutant proteins exhibited a range of defects including the failure to assemble the dipyrromethane cofactor and the inability to initiate and propagate the tetrapolymerization reaction. Mutations of arginine residues at positions 11, 131, 132 and 155, all of which interact with the carboxylic acid side chains of the dipyrromethane cofactor, were the most disruptive.
Jordan
P M
PM
School of Biological Sciences, Queen Mary College, University of London, U.K.
Woodcock
S C
SC
D000595:Amino Acid Sequence; D001120:Arginine / Q000235:genetics*; D002384:Catalysis; D002853:Chromatography, Liquid; D004926:Escherichia coli / Q000201:enzymology*; D011163:Hydroxymethylbilane Synthase / Q000235:genetics* / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010441:Peptide Chain Elongation, Translational; D010442:Peptide Chain Initiation, Translational; D011162:Porphobilinogen / Q000378:metabolism*; D011758:Pyrroles / Q000378:metabolism*; D045725:Tetrapyrroles
D011758:Pyrroles; D045725:Tetrapyrroles; C056776:dipyrromethane cofactor; D011162:Porphobilinogen; D001120:Arginine; D011163:Hydroxymethylbilane Synthase