Recombinant expression and isolation of human L-arginine:glycine amidinotransferase and identification of its active-site cysteine residue.
Creatine and its phosphorylated form play a central role in the energy metabolism of muscle and nerve tissues. l-Arginine:glycine amidinotransferase (AT) catalyses the committed step in the formation of creatine. The mitochondrial and cytosolic forms of the enzyme are believed to derive from the same gene by alternative splicing. We have expressed recombinant human AT in Escherichia coli with two different N-termini, resembling the longest two forms of the enzyme that we had isolated recently from porcine kidney mitochondria as a mixture. The enzymes were expressed with N-terminal histidine tags followed by factor Xa-cleavage sites. We established a new method for the removal of N-terminal fusion peptides by means of an immobilized snake venom prothrombin activator. We identified cysteine-407 as the active-site residue of AT by radioactive labelling and isolation of labelled peptides, and by site-directed mutagenesis of the protein.
Humm
A
A
Max-Planck-Institut für Biochemie, Am Klopferspitz 18a, 82152 Martinsried, Germany.
Fritsche
E
E
Mann
K
K
Göhl
M
M
Huber
R
R
D000579:Amidinotransferases / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification; D016415:Sequence Alignment; D013379:Substrate Specificity
D011994:Recombinant Proteins; D000579:Amidinotransferases; C020681:glycine amidinotransferase; D003545:Cysteine