Structural basis for a reciprocating mechanism of negative cooperativity in dimeric phosphagen kinase activity.
Phosphagen kinase (PK) family members catalyze the reversible phosphoryl transfer between phosphagen and ADP to reserve or release energy in cell energy metabolism. The structures of classic quaternary complexes of dimeric creatine kinase (CK) revealed asymmetric ligand binding states of two protomers, but the significance and mechanism remain unclear. To understand this negative cooperativity further, we determined the first structure of dimeric arginine kinase (dAK), another PK family member, at 1.75 A, as well as the structure of its ternary complex with AMPPNP and arginine. Further structural analysis shows that the ligand-free protomer in a ligand-bound dimer opens more widely than the protomers in a ligand-free dimer, which leads to three different states of a dAK protomer. The unexpected allostery of the ligand-free protomer in a ligand-bound dimer should be relayed from the ligand-binding-induced allostery of its adjacent protomer. Mutations that weaken the interprotomer connections dramatically reduced the catalytic activities of dAK, indicating the importance of the allosteric propagation mediated by the homodimer interface. These results suggest a reciprocating mechanism of dimeric PK, which is shared by other ATP related oligomeric enzymes, e.g., ATP synthase.
Laboratory of Structural Biology, Tsinghua University, Beijing, China.
Xiaoai
X
Wu
Sheng
S
Ye
Shuyuan
S
Guo
Wupeng
W
Yan
Mark
M
Bartlam
Zihe
Z
Rao
D000266:Adenylyl Imidodiphosphate / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001122:Arginine Kinase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain / Q000235:genetics; D003402:Creatine Kinase / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D019281:Dimerization; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017852:Phosphotransferases (Nitrogenous Group Acceptor) / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012616:Sea Cucumbers / Q000201:enzymology / Q000235:genetics; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity
D008024:Ligands; D011994:Recombinant Proteins; D000266:Adenylyl Imidodiphosphate; D017852:Phosphotransferases (Nitrogenous Group Acceptor); D003402:Creatine Kinase; D001122:Arginine Kinase