Identification of polyphosphate-binding proteins in

In many bacteria, polyphosphate kinase (PPK) enzymes use ATP to synthesize polyphosphate (polyP) in response to cellular stress. These chains of inorganic phosphates are joined by high-energy bonds and can reach hundreds of residues in length. PolyP plays diverse functions in helping bacteria adjust to changing environmental conditions. However, the molecular mechanisms underlying these functions are poorly understood. In eukaryotic cells, polyacidic serine- and lysine-rich (PASK) motifs of proteins can mediate binding to polyP chains. Whereas PASK motifs are relatively common in yeast and human cells, we report that these sequences are rare in bacteria commonly used for polyP research. Thus, to identify novel polyP-binding proteins in IMPORTANCE: In bacteria, polyphosphate (polyP) molecules are important regulators of cellular stress responses. Accordingly, cells that cannot make polyP display defects in processes that are important for bacterial survival, infection, and antibiotic resistance. The molecular mechanisms by which polyP exerts its functions are poorly understood. In eukaryotic cells, there has been much interest in the identification and characterization of polyP-binding proteins that act as effectors of polyP