Polyphosphates in the Cell Envelopes of Prokaryotes

The cell envelopes of bacteria play an essential role in bacterial virulence, surface attachment and biofilm formation (O Toole et al, 2000). This cell compartment possesses PolyPs, and thereby its role in the above functions was intensively investigated. The conclusion was 

PolyP was shown to be a component of the cell capsule of Neisseria. These capsular PolyPs were about a half of the cellular content of PolyP (Tinsley et al, 1993). The polyphosphate kinase deficient mutant of Neisseria had a reduced PolyP pool and a lower pathogenicity than the wild-type strain (Tinsley and Gotschlich, 1995). 

The ppk mutant of P. aeruginosa was also deficient in type-IV pili-mediated twitching and in swarming motility (Rashid and Kornberg, 2000). Some suggestions on the molecular mechanisms of PolyP- PPK action in motility were made (Rashid and Kornberg, 2000). These included the possible role of PolyP in the phosphorylation of Che-Y-like proteins or modulation of the Ca2+ level (Rashid and Kornberg, 2000). 

The role of PolyP in the cell envelope of prokaryotes may be connected with their anionic properties, important for providing the negative charge of this compartment. In addition, PolyPs may affect the cell-envelope functions by gene activity regulation, as will be discussed below. 

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