Polyphosphate kinase 1, a conserved bacterial enzyme, in a eukaryote, Dictyostelium discoideum , with a role in cytokinesis

Abstract

Polyphosphate kinase 1 (PPK1), the principal enzyme responsible for reversible synthesis of polyphosphate (poly P) from the terminal phosphate of ATP, is highly conserved in bacteria and archaea. Dictyostelium discoideum, a social slime mold, is one of a few eukaryotes known to possess a PPK1 homolog (DdPPK1). Compared with PPK1 of Escherichia coli, DdPPK1 contains the conserved residues for ATP binding and autophosphorylation, but has an N-terminal extension of 370 aa, lacking homology with any known protein. Polyphosphate or ATP promote oligomerization of the enzyme in vitro. The DdPPK1 products are heterogeneous in chain length and shorter than those of E. coli. The unique DdPPK1 N-terminal domain was shown to be necessary for its enzymatic activity, cellular localization, and physiological functions. Mutants of DdPPK1, as previously reported, are defective in development, sporulation, and predation, and as shown here, in late stages of cytokinesis and cell division.inorganic polyphosphate ͉ cell division ͉ multinucleated cells

Developmental accumulation of inorganic polyphosphate affects germination and energetic metabolism in Dictyostelium discoideum

“…The characterization of two D. discoideum enzymes Ppk1 (20) and DdPPK2 (22) able to synthesize polyP in vitro suggested that both enzymes might contribute to the synthesis of polyP in vivo. DdPPK2 has been identified as an actin-related protein complex but the specific gene was not cloned.…”

“…The first, DdPPK1 (hereafter refer as Ppk1), was identified by homology to the bacterial polyphosphate kinase (PPK) sequence (20). Dictyostelids represent the only eukaryote class possessing a bacterial-like PPK, suggesting the gene was obtained by a horizontal gene transfer event (20). The second protein complex, named DdPPK2, was identified after biochemical purification of polyphosphate kinase activity and was found to comprise one actin-related protein and two actin-associated proteins (21).…”

“…The second protein complex, named DdPPK2, was identified after biochemical purification of polyphosphate kinase activity and was found to comprise one actin-related protein and two actin-associated proteins (21). Whereas the in vitro biochemical properties of these two enzymes have been studied (20,22), little is known about D. discoideum polyP metabolism and the contribution of these proteins to in vivo polyP synthesis, or the physiological function of polyP. Therefore, we have used a recently refined biochemical procedure to study polyP metabolism in D. discoideum.…”

“…Kornberg's laboratory described two enzymes able to synthesize polyP in D. discoideum. The first, DdPPK1 (hereafter refer as Ppk1), was identified by homology to the bacterial polyphosphate kinase (PPK) sequence (20). Dictyostelids represent the only eukaryote class possessing a bacterial-like PPK, suggesting the gene was obtained by a horizontal gene transfer event (20).…”

Transcriptome analysis ofCampylobacter jejunipolyphosphate kinase (ppk1andppk2) mutants

“…Transcriptome analysis of Campylobacter jejuni polyphosphate kinase (ppk1 and ppk2) mutants the synthesis of poly-P, [11][12][13] while PPK2 preferentially facilitates the generation of GTP from poly-P. [14][15] Both PPK1 and PPK2 (PPKs) contribute to survival, adaptation, and virulence in many bacterial pathogens. 11 For example, we have shown that the impairment of the ppks (ppk1 and ppk2) can affect a wide range of phenotypes in C. jejuni, [4][5][6] including biofilm formation, and the resistance to osmotic, nutrient, and antimicrobial stresses.…”