title: Characterization of a eukaryotic-like protein kinase, DspB, with an atypical catalytic loop motif from Myxococcus xanthus.
abstract: Serine (Ser)/threonine (Thr) or tyrosine (Tyr) protein kinases in eukaryotes contain RDxKxxN or RDx(A/R)A(A/R)N sequences, respectively, in the catalytic loop. Myxococcus xanthus DspB is a dual-specificity kinase that contains an atypical sequence, RDVAQKN, in the catalytic loop. The DspB mutant (A165K), which contains the canonical RDxKxxN motif, had an approximate 1.3-fold increase in kinase activity toward myelin basic protein (MBP). Arginine-aspartate (RD) kinases carry a conserved Arg immediately preceding the catalytic Asp that is required for autophosphorylation of the activation loop. DspB belongs to the RD kinase family and contains one Ser residue (Ser-190) and one Thr residue (Thr-194) in the activation loop. Mutation of Ser-190 or Thr-194 to Ala did not significantly affect the kinase activity toward MBP. We previously reported that four M. xanthus eukaryotic-like kinases (EPKs) are autophosphorylated on Tyr residues. These EPKs contain six Tyr residues at homologous positions, and five of those Tyr residues, Y25, Y102, Y145, Y173, and Y205, are conserved in DspB. DspB is mainly autophosphorylated on Y145, and a Y145F mutant has reduced kinase activity, suggesting that autophosphorylation of the Tyr residue of DspB may be required for high-level kinase activity.
authors.affiliation: Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kagawa, 761-0795, Japan. kimura@ag.kagawa-u.ac.jp.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Kimura
authors.affiliation: Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kagawa, 761-0795, Japan.
authors.forename: Maho
authors.initials: M
authors.lastname: Urata
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002384:Catalysis; D056890:Eukaryota / Q000201:enzymology; D006801:Humans; D008969:Molecular Sequence Data; D016941:Myxococcus xanthus / Q000201:enzymology*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
chemical_list: D017346:Protein Serine-Threonine Kinases
keywords: Atypical catalytic loop; Dual-specificity kinase; Eukaryotic-like protein kinase; Myxococcus xanthus; RD kinase