Enzymatic characteristics of a Ser/Thr protein kinase, SpkA, from Myxococcus xanthus

Yoshio Kimura, Aoi Kakemizu, Yuuko Matsubara, Kaoru Takegawa

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1 Citation (Scopus)


Two Ser/Thr protein kinases, SpkA and SpkB, selected from Myxococcus xanthus based on amino acid sequence similarities with the catalytic subunits of cAMP-dependent protein kinases (PKA) were synthesized using a cell-free protein synthesis system. In various protein kinase assays, purified StkA and StkB showed their highest protein kinase activities in a PKA assay using the selective PKA substrate Kemptide and in a protein kinase C (PKC) assay using the selective PKC substrate neurogranin(28-43), respectively. SpkA had apparent Km values of 45 μM and 37 μM for Kemptide and ATP, respectively. Phosphorylation of Kemptide was inhibited by a specific PKA inhibitor peptide, PKI5-24, and the IC50 and Ki values for inhibition of the SpkA activity were 117 nM and 36 nM, respectively.

Original languageEnglish
Pages (from-to)10-15
Number of pages6
JournalJournal of Bioscience and Bioengineering
Issue number1
Publication statusPublished - Jan 2009

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology


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