Page 142 - The Biochemistry of Inorganic Polyphosphates

WU095/Kulaev
WU095-08
Peculiarities of polyphosphate metabolism
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Orthophosphate (µg mg −1 ) 10 3 4 1 1.2 mg biomass/ml medium
1.0
2
0.8
0.6
1
0.4
2
0.2
Activity of enzyme (mE (mg protein −1 )) 0.2 6
8
6
4
2
5
7

8
0.1

500
120 240 360 480 9
Time (min)
Figure 8.1 PolyP and PolyP-metabolizing enzymes during the growth of E. coli K-12: (1) biomass;
(2) PolyP; (3) intracellular P i ; (4) exogenous P i ; (5) exopolyphosphatase; (6) tripolyphosphatase; (7)
alkaline phosphatase; (8) polyphosphate kinase; (9) 1,3-diphosphoglycerate:polyphosphate phospho-
transferase (Nesmeyanova et al., 1973).

medium supported such a suggestion, simultaneously closing the question of PolyP oc-
currence in E. coli (Nesmeyanova et al., 1973, 1974a,b, 1975a,b; Nesmeyanova, 2000). A
high-molecular-weight acid-insoluble PolyP was found in this bacterium and identified by
a specific product of its partial acidic hydrolysis, i.e. cyclotriphosphate, using the method
of Thilo and Wieker (1957). The highest amount of this high-polymer PolyP, reaching 0.2–
0.4 % of dry bacterial weight (in yeast, its amount may reach 20 %), occurs in the cells of
this bacterium only at the end of the latent and the beginning of the logarithmic growth
phase (Nesmeyanova et al., 1973). When the culture passes to exponential growth, the level
of intracellular PolyP dramatically decreases 5–10-fold (Figure 8.1). Thus, the accumula-
tion of PolyP precedes intensive culture growth, and then it is utilized by the growing cells
(Nesmeyanova et al., 1973).
The accumulation of PolyPs in cells results from two processes: synthesis and utilization
of PolyP. The dynamics of the known PolyP-synthesizing enzymes, i.e. polyphosphate
kinase and 1,3-diphosphoglycerol-polyphosphate phosphotransferase, showed that these
enzyme activities weakly correlate with the dynamics of PolyP accumulation under standard
growth conditions (see Figure 8.1). The main peak of polyphosphate kinase activity was