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.
Institute of Cell Biology, Swiss Federal Institute of Technology Zürich, CH-8093 Zürich, Switzerland. forstner1@llnl.gov
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Forstner
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Kriechbaum
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Laggner
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Wallimann
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