Contributions to catalysis and potential interactions of the three catalytic domains in a contiguous trimeric creatine kinase.
Three separate creatine kinase (CK) isoform families exist in animals. Two of these (cytoplasmic and mitochondrial) are obligate oligomers. A third, flagellar, is monomeric but contains the residues for three complete CK domains. It is not known whether the active sites in each of the contiguous flagellar domains are catalytically competent, and, if so, whether they are capable of acting independently. Here we have utilized site-directed mutagenesis to selectively disable individual active sites and all possible combinations thereof. Kinetic studies showed that these mutations had minimal impact on substrate binding and synergism. Interestingly, the active sites were not catalytically equivalent, and were in fact interdependent, a phenomenon that has previously been reported only in the oligomeric CK isoforms.
Hoffman
Gregg G
GG
Department of Biological Science, Florida State University, Tallahassee, FL, USA.
Davulcu
Omar
O
Sona
Sona
S
Ellington
W Ross
WR
D000595:Amino Acid Sequence; D000818:Animals; D002384:Catalysis; D020134:Catalytic Domain / Q000235:genetics; D003402:Creatine Kinase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011077:Polychaeta / Q000201:enzymology* / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D011994:Recombinant Proteins; D003402:Creatine Kinase