title: An effective sporulation of Myxococcus xanthus requires glycogen consumption via Pkn4-activated 6-phosphofructokinase.
abstract: 6-Phosphofructokinase (PFK) is a key enzyme for glycolysis in both prokaryotes and eukaryotes. Previously, it was found that the activity of Myxococcus xanthus PFK increased 2.7-fold upon phosphorylation at Thr-226 by the Ser/Thr kinase Pkn4. The pkn4 gene is located 18 bp downstream of the pfk gene forming an operon, and both genes are expressed during vegetative growth and development. Here, we show that glycogen, which accumulates during stationary phase and early in development, is consumed during sporulation. A pfk-pkn4 deletion strain accumulated glycogen at a higher level than the wild-type strain, was unable to consume glycogen during developmental progression and exhibited a poor spore yield. From genetic complementation analysis of the pfk-pkn4 deletion strain with the pfk and pkn4 genes, it was found that glycogen consumption and a high spore yield require not only the pfk gene but also the pkn4 gene. Furthermore, phosphorylation is critical for glycogen consumption because the pfk gene engineered to express the mutant PFK (Thr-226-Ala) did not complement a pfk mutant. We propose that glycogen metabolism in M. xanthus is regulated in a similar manner to that in eukaryotes requiring a protein Ser/Thr kinase.
authors.affiliation: Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Nariya
authors.forename: Sumiko
authors.initials: S
authors.lastname: Inouye
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004789:Enzyme Activation; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006003:Glycogen / Q000378:metabolism*; D016941:Myxococcus xanthus / Q000201:enzymology* / Q000502:physiology*; D009876:Operon; D010732:Phosphofructokinase-1 / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D006003:Glycogen; C043075:phosphofructokinase regulatory subunit; D010732:Phosphofructokinase-1; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases