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Modulating factors for the Pkn4 kinase cascade in regulating 6-phosphofructokinase in Myxococcus xanthus

Hirofumi Nariya1, Sumiko Inouye

  • 1Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA.

Molecular Microbiology
|May 11, 2005
PubMed

Insights

Myxococcus xanthus protein kinases regulate bacterial development. New factors, MkapA, MkapB, and MkapC, interact with Pkn4, influencing glycogen consumption and sporulation efficiency.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Myxococcus xanthus possesses numerous protein Ser/Thr kinases (PSTKs).
  • Pkn4 acts as a 6-phosphofructokinase (PFK) kinase, activating PFK through phosphorylation for glycogen consumption and sporulation.

Purpose of the Study:

  • To identify novel proteins interacting with Pkn4.
  • To elucidate the role of these interactions in M. xanthus development and PSTK networks.

Main Methods:

  • Yeast two-hybrid screening to identify Pkn4 interacting partners.
  • Analysis of deletion mutants (pfk-pkn4 operon, mkapB) to assess developmental phenotypes.

Main Results:

  • Identified MkapA, MkapB, and MkapC as Pkn4 interactors, with MkapB binding being phosphorylation-dependent.
  • MkapB binding to Pkn4 inhibited Pkn4-PFK interaction and PFK activation.
  • mkapB deletion mutants showed delayed fruiting body formation, reduced glycogen, and significantly lower spore yield.

Conclusions:

  • MkapB acts as a negative regulator of Pkn4-mediated PFK activation, crucial for efficient sporulation in M. xanthus.
  • MkapA, MkapB, and MkapC are involved in complex PSTK networks, modulating multiple kinases in M. xanthus.

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