Functional analysis of conserved motifs in a bacterial tyrosine kinase, BtkB, from Myxococcus xanthus

Takuya Kato, Yuuki Shirakawa, Kaoru Takegawa, Yoshio Kimura

Research output: Contribution to journalArticle

Abstract

Myxococcus xanthus has two bacterial protein-tyrosine (BY) kinases, BtkA and BtkB. Autophosphorylation in C-terminal tyrosine-rich clusters and poly(Glu, Tyr) kinase activities of cytoplasmic catalytic domains of BtkA and BtkB were activated by the intracellular juxtamembrane regions of the second transmembrane helices. Protein kinase activity against poly(Glu, Tyr) of cytoplasmic fragment of BtkB (CF-BtkB) containing an activator region was not inhibited by serine/threonine protein kinase inhibitors. However, addition of tyrosine protein kinase inhibitors, genistein and 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2), at a concentration of 0.2 mM, inhibited the CF-BtkB kinase activity by 20 and 64%, respectively. A CF-BtkB mutant constructed by replacing all C-terminal tyrosine residues with phenylalanines, did not undergo autophosphorylation. Further, this mutation did not significantly affect poly(Glu, Tyr) kinase activity, suggesting that M. xanthus BtkB kinase activity is not dependent on autophosphorylation in the C-terminal tyrosine cluster. A conserved motif (ExxRxxR) of BY kinases is involved in the self-association of catalytic domains of BY kinases, necessary to accomplish trans-phosphorylation. An ExxRxxR motif mutant of CF-BtkB led to loss of autophosphorylation and poly(Glu, Tyr) kinase activities. These observations provide insights into the regulation mechanism of M. xanthus BY kinase activity.

Original languageEnglish
Pages (from-to)385-392
Number of pages8
JournalJournal of biochemistry
Volume158
Issue number5
DOIs
Publication statusPublished - Mar 3 2015

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Myxococcus xanthus
Functional analysis
Protein-Tyrosine Kinases
Phosphotransferases
Tyrosine
Protein Kinase Inhibitors
Catalytic Domain
Bacterial Proteins
Genistein
Protein-Serine-Threonine Kinases
Phosphorylation
Phenylalanine
Protein Kinases
Association reactions
Mutation

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology

Cite this

Functional analysis of conserved motifs in a bacterial tyrosine kinase, BtkB, from Myxococcus xanthus. / Kato, Takuya; Shirakawa, Yuuki; Takegawa, Kaoru; Kimura, Yoshio.

In: Journal of biochemistry, Vol. 158, No. 5, 03.03.2015, p. 385-392.

Research output: Contribution to journalArticle

Kato, Takuya ; Shirakawa, Yuuki ; Takegawa, Kaoru ; Kimura, Yoshio. / Functional analysis of conserved motifs in a bacterial tyrosine kinase, BtkB, from Myxococcus xanthus. In: Journal of biochemistry. 2015 ; Vol. 158, No. 5. pp. 385-392.
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