Activating Compound | Comment | Organism | Structure |
---|---|---|---|
additional information | autophosphorylation at Thr825 activates MHCK A at least 50fold, dephosphorylation of the residue reduces the activity | Dictyostelium discoideum |
Cloned (Comment) | Organism |
---|---|
expression of FLAG-tagged T825A and T825E enzyme mutants in Dictyostelium discoideum cells, expression of His-tagged wild-type and mutant MHCK A alpha-kinase domains in Escherichia coli strain BL21(DE3) | Dictyostelium discoideum |
Crystallization (Comment) | Organism |
---|---|
purified recombinant wild-type and truncation mutant enzymes, hanging drop vapor diffusion method, mixing of 0.001 ml protein solution with 0.001 ml of reservoir solution containing 0.1 M Tris-HCl, pH 8.5, 0.2 M NaH2PO4, and 18% w/v PEG 8000, 4°C, 10 days, X-ray diffraction structure determination and analysis at 1.9 A resolution | Dictyostelium discoideum |
Protein Variants | Comment | Organism |
---|---|---|
additional information | generation of a DELTA809 truncation mutant, phosphothreonine and the QQG(p)TMVMPD peptide restore the phosphorylation and also the ATPase activity of the mutant alpha-kinade domain, but mutations R734A and D762A abolish the ability of phosphothreonine to activate mutant alpha-kinase domain DELTA809 | Dictyostelium discoideum |
Q822R/Q823R/T825S | site-directed mutagenesis | Dictyostelium discoideum |
T825A | site-directed mutagenesis | Dictyostelium discoideum |
T825E | site-directed mutagenesis | Dictyostelium discoideum |
T825S | site-directed mutagenesis, the mutant shows reduced activity compared to the wild-type enzyme | Dictyostelium discoideum |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Mg2+ | required, the Mg2 binding sites are regulatory, because millimolar concentrations of Mg2+, in excess of that required to bind to ATP, are required for A-CAT to exhibit maximal catalytic activity | Dictyostelium discoideum |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
ATP + [myosin heavy-chain] | Dictyostelium discoideum | - |
ADP + [myosin heavy-chain] phosphate | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Dictyostelium discoideum | P42527 | - |
- |
Posttranslational Modification | Comment | Organism |
---|---|---|
phosphoprotein | autophosphorylation at Thr825 activates MHCK A at least 50fold, dephosphorylation of the residue reduces the activity. The phosphorylated Thr825 docks intramolecularly into the phosphate-pocket. Allosteric activation is predicted to involve a conformational change in Arg734, which bridges the bound phosphate to Asp762 in a key active site loop | Dictyostelium discoideum |
Purification (Comment) | Organism |
---|---|
recombinant His-tagged wild-type and mutant MHCK A alpha-kinase domains from Escherichia coli strain BL21(DE3) by nickel affinity chromatography | Dictyostelium discoideum |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
ATP + [myosin heavy-chain] | - |
Dictyostelium discoideum | ADP + [myosin heavy-chain] phosphate | - |
? | |
additional information | the enzyme performs autophosphorylation at Thr825 | Dictyostelium discoideum | ? | - |
? |
Synonyms | Comment | Organism |
---|---|---|
MHCK A | - |
Dictyostelium discoideum |
myosin II heavy chain kinase A | - |
Dictyostelium discoideum |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
22 | - |
assay at | Dictyostelium discoideum |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
7 | - |
assay at | Dictyostelium discoideum |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
ATP | - |
Dictyostelium discoideum |
General Information | Comment | Organism |
---|---|---|
evolution | myosin II heavy chain kinase A is a member of the atypical alpha-kinase family | Dictyostelium discoideum |
malfunction | the catalytic activity of A-CAT, the alpha-kinase domain of MHCKA comprising residues 552-841, is severely inhibited by the removal of a disordered C-terminal tail residues 806-841 | Dictyostelium discoideum |
additional information | the phosphate-pocket functions as a positive allosteric binding site, the phosphorylated Thr825 activates alpha-kinase domain by providing a covalently tethered ligand for the phosphate-pocket, mechanism modeling | Dictyostelium discoideum |
physiological function | the enzyme phosphorylates sites in the myosin II tail that block filament assembly | Dictyostelium discoideum |