Structural changes of creatine kinase upon substrate binding.
Small-angle x-ray scattering was used to investigate structural changes upon binding of individual substrates or a transition state analog complex (TSAC; Mg-ADP, creatine, and KNO3) to creatine kinase (CK) isoenzymes (dimeric muscle-type (M)-CK and octameric mitochondrial (Mi)-CK) and monomeric arginine kinase (AK). Considerable changes in the shape and the size of the molecules occurred upon binding of Mg-nucleotide or TSAC. The radius of gyration of Mi-CK was reduced from 55.6 A (free enzyme) to 48.9 A (enzyme plus Mg-ATP) and to 48.2 A (enzyme plus TSAC). M-CK showed similar changes from 28.0 A (free enzyme) to 25.6 A (enzyme plus Mg-ATP) and to 25.5 A (enzyme plus TSAC). Creatine alone did not lead to significant changes in the radii of gyration, nor did free ATP or ADP. AK also showed a change of the radius of gyration from 21.5 A (free enzyme) to 19.7 A (enzyme plus Mg-ATP), whereas with arginine alone only a minor change could be observed. The primary change in structure as seen with monomeric AK seems to be a Mg-nucleotide-induced domain movement relative to each other, whereas the effect of substrate may be of local order only. In CK, however, additional movements have to be involved.
Forstner
M
M
Institute of Cell Biology, Swiss Federal Institute of Technology Zürich, CH-8093 Zürich, Switzerland. forstner1@llnl.gov
Kriechbaum
M
M
Laggner
P
P
Wallimann
T
T
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000465:Algorithms; D000818:Animals; D001122:Arginine Kinase / Q000737:chemistry* / Q000378:metabolism*; D002645:Chickens; D003001:Cloning, Molecular; D003198:Computer Simulation; D003402:Creatine Kinase / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray / Q000379:methods; D019281:Dimerization; D004926:Escherichia coli; D007527:Isoenzymes; D008928:Mitochondria / Q000201:enzymology; D008931:Mitochondria, Muscle / Q000201:enzymology; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012518:Sarcomeres / Q000201:enzymology; D012542:Scattering, Radiation; D014965:X-Rays
D007527:Isoenzymes; D011994:Recombinant Proteins; D000255:Adenosine Triphosphate; D003402:Creatine Kinase; D001122:Arginine Kinase