Eukaryote polyphosphate kinases: is the 'Kornberg' complex ubiquitous?

Area of Science:

• Cell Biology
• Molecular Evolution
• Biochemistry

Background:

• Polyphosphate (poly P) is a polymer of phosphate residues crucial for cellular functions.
• Polyphosphate kinase 1 (PPK1), a primary enzyme for poly P synthesis, was previously found mainly in bacteria and some protists.
• The discovery of PPK1 homologues and a second bacterial-type enzyme, PPK2, in diverse eukaryotes is recent.

Purpose of the Study:

• To investigate the presence and distribution of polyphosphate-synthesizing enzymes in eukaryotes.
• To explore the evolutionary significance of polyphosphate metabolism in eukaryotic cell development.

Main Methods:

• Bioinformatic analysis of genome databases.
• Identification and characterization of PPK1 and PPK2 homologues across eukaryotic species.
• Comparative genomics to assess enzyme distribution.

Main Results:

• PPK1 homologues and PPK2 enzymes are present in a wider range of eukaryotes than previously known.
• A 'Kornberg' enzyme complex (DdPPK2) involving actin-related proteins may be ubiquitous in eukaryotes.
• Polyphosphate synthesis is closely linked to structural fiber formation.

Conclusions:

• The widespread presence of polyphosphate synthesis machinery suggests a fundamental role in eukaryotic evolution.
• Polyphosphate likely plays a central role in the development and structural organization of eukaryotic cells.
• Further research into polyphosphate's function in eukaryotes is warranted.