Page 138 - The Biochemistry of Inorganic Polyphosphates

WU095/Kulaev
WU095-07
Functions of polyphosphate and polyphosphate-dependent enzymes
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P i reserve Participation in mannan Ionic and pH homeostasis, P i
biosynthesis, negative charge reservation
n
stabilizatio
Energy reservation

Cytosol Cell envelope
Vacuole

Mitochondria
Nucleus

Gene-activity
regulation

Membranes

PolyP/PHB complexes, ionic channels

Figure 7.10 The localization and functions of PolyPs in lower eukaryotes.

quite significant. This is confirmed by the presence of such compounds in nearly all tissues
and organs.
In conclusion, it should be noted that PolyPs are polyfunctional compounds. Their most
important functions are as follows: phosphate and energy reservation, sequestration and
storage of cations, formation of membrane channels, participation in phosphate transport,
involvement in cell-envelope formation and function, gene activity control, regulation of
enzyme activities, and, as a result, an important role in stress response and stationary-phase
adaptation.
The functions of PolyPs have changed greatly during the evolution of living organisms.
Figures 7.9–7.11 summarize, respectively, data on PolyP functions in prokaryotes, lower
eukaryotes and animals. In microbial cells, they play a significant role, increasing cell
resistance to unfavourable environmental conditions and regulating different biochemical