Premium
Pph1 from Myxococcus xanthus is a protein phosphatase involved in vegetative growth and development
Author(s) -
TreunerLange Anke,
Ward Mandy J.,
Zusman David R.
Publication year - 2001
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2001.02362.x
Subject(s) - myxococcus xanthus , biology , phosphatase , protein phosphatase 2 , biochemistry , mutant , kinase , microbiology and biotechnology , phosphorylation , gene
Myxococcus xanthus is a Gram‐negative bacterium with a complex life cycle that includes vegetative swarming on rich medium and, upon starvation, aggregation to form fruiting bodies containing spores. Both of these behaviours require multiple Ser/Thr protein kinases. In this paper, we report the first Ser/Thr protein phosphatase gene, pph1 , from M. xanthus . DNA sequence analysis of pph1 indicates that it encodes a protein of 254 residues ( M r = 28 308) with strong homology to eukaryotic PP2C phosphatases and that it belongs to a new group of bacterial protein phosphatases that are distinct from bacterial PP2C phosphatases such as RsbU, RsbX and SpoIIE. Recombinant His‐tagged Pph1 was purified from Escherichia coli and shown to have Mn 2+ or Mg 2+ dependent, okadaic acid‐resistant phosphatase activity on a synthetic phosphorylated peptide, RRA(pT)VA, indicating that Pph1 is a PP2C phosphatase. Pph1‐expression was observed under both vegetative and developmental conditions, but peaked during early aggregation. A pph1 null mutant showed defects during late vegetative growth, swarming and glycerol spore formation. Under starvation‐induced developmental conditions, the mutant showed reduced aggregation and failure to form fruiting bodies with viable spores. Using the yeast two‐hybrid system, we have observed a strong interaction between Pph1 and the M. xanthus protein kinase Pkn5, a negative effector of development. These results suggest a functional link between a Pkn2‐type protein kinase and a PP2C phosphatase.