On the domain construction of the multienzyme gramicidin S synthetase 2. Isolation of domains activating valine and leucine.
The multienzyme gramicidin S synthetase 2, composed of one polypeptide chain, was treated with trypsin and chymotrypsin to give fragments retaining partial enzyme activities. Previously, a tryptic fragment of this multienzyme has been identified as a structural and functional domain. In this study two more fragments, activating Leu and Val, respectively, are shown to represent domains. Careful inspection of the data on limited proteolysis, from this study as well as from previous work, suggests that domains are not simply connected like pearls on a string, and a model for the structure of gramicidin S synthetase, with implications for other peptide synthetase multienzymes, is presented. It is suggested that gramicidin S synthetase 2 is constructed from core catalytic domains and intervening framework. Such an interpretation is in accordance with all published data on limited proteolysis of peptide synthetases, but needs an interplay with gene structural studies in order to be validated and refined.
Biokjemisk Institutt, University of Oslo, Norway.
H J
HJ
Skarpeid
T L
TL
Zimmer
H
H
von Döhren
D000591:Amino Acid Isomerases / Q000032:analysis* / Q000378:metabolism; D001407:Bacillus / Q000201:enzymology; D001665:Binding Sites; D002850:Chromatography, Gel; D002853:Chromatography, Liquid / Q000379:methods; D002918:Chymotrypsin; D004591:Electrophoresis, Polyacrylamide Gel; D007930:Leucine; D009097:Multienzyme Complexes / Q000032:analysis* / Q000378:metabolism; D010446:Peptide Fragments / Q000032:analysis; D010447:Peptide Hydrolases; D010453:Peptide Synthases / Q000032:analysis* / Q000378:metabolism; D014357:Trypsin; D014633:Valine
D009097:Multienzyme Complexes; D010446:Peptide Fragments; D010447:Peptide Hydrolases; D002918:Chymotrypsin; D014357:Trypsin; D000591:Amino Acid Isomerases; D010453:Peptide Synthases; C020831:gramicidin-S-synthetase 2; D007930:Leucine; D014633:Valine