Cyclosporin synthetase. The most complex peptide synthesizing multienzyme polypeptide so far described.
Cyclosporin A and its homologues are synthesized by a single multifunctional enzyme from their precursor amino acids. Cyclosporin synthetase is a polypeptide chain with a molecular mass of approximately 800 kDa. In 3% polyacrylamide-sodium dodecyl sulfate gels it shows a single band of approximately 650 kDa, which appears to not be glycosylated. The enzyme could be purified to near-homogeneity in five steps. A 72-fold purification was obtained. All constitutive amino acids of cyclosporins are activated as thioesters via aminoadenylation by the same enzyme. Then N-methylation of the thioester-bound amino acids which are present in methylated form in the cyclosporin molecule takes place, whereby S-adenosyl-L-methionine serves as the methyl group donor. Methyltransferase activity is an integral entity of the enzyme; this could be shown by a photoaffinity labeling method. 4'-Phosphopantetheine is a prosthetic group of cyclosporin synthetase similar to other peptide and depsipeptide synthetases. Cyclosporin synthetase shows cross-reactions with monoclonal antibodies directed against enniatin synthetase.
Lawen
A
A
Institut für Biochemie und Molekulare Biologie, Technische Universität Berlin, Federal Republic of Germany.
Zocher
R
R
D000345:Affinity Labels; D000596:Amino Acids / Q000378:metabolism; D002241:Carbohydrates / Q000032:analysis; D002499:Centrifugation, Density Gradient; D003524:Cyclosporins / Q000096:biosynthesis; D015151:Immunoblotting; D008745:Methylation; D003904:Mitosporic Fungi / Q000201:enzymology*; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000302:isolation & purification* / Q000378:metabolism; D010204:Pantetheine / Q000031:analogs & derivatives / Q000032:analysis; D010453:Peptide Synthases / Q000302:isolation & purification* / Q000378:metabolism; D010777:Photochemistry; D012436:S-Adenosylmethionine / Q000378:metabolism; D014242:Trichoderma / Q000201:enzymology*
D000345:Affinity Labels; D000596:Amino Acids; D002241:Carbohydrates; D003524:Cyclosporins; D009097:Multienzyme Complexes; C048525:cyclosporin A synthetase; D010204:Pantetheine; D012436:S-Adenosylmethionine; D010453:Peptide Synthases; C003129:4'-phosphopantetheine