Page 182 - The Biochemistry of Inorganic Polyphosphates

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Peculiarities of polyphosphate metabolism
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during the first few hours of spore germination in Aspergillus niger. The utilization of
PolyP during the active RNA synthesis was also demonstrated in other fungi (Kulaev et al.,
1960a-c; Harold, 1962b, 1966; Kritsky et al., 1965a,b, 1968; Kulaev and Vagabov, 1983).
A 31 P NMR spectroscopic analysis of the PolyP pool in cellular and nuclear extracts
of Physarum polycephalum (Pilatus et al., 1989) demonstrated that plasmodia and cycts
contained PolyP with an average chain length of about 100 residues. During sporulation,
this PolyP degrades to a lower one with a chain length of ∼ 10 residues. PolyP was degraded
at a sufficient amount of P i , and it was concluded that the PolyP serves to supply energy for
biosynthetic processes during sporulation.
Some authors have suggested that PolyP utilization during spore germination provided
the required osmotic pressure for the ‘explosion’ of cysts and penetration of germ cells
of pathogenic fungi into the cells of host organisms (Kulaev and Vagabov, 1983). It was
proposed that such osmotic pressure developed during PolyP hydrolysis in the lamellae of
the fruiting bodies of Agaricus bisporius involved in spore dissemination (Kulaev et al.,
1960a,b; Kritsky et al., 1965a,b). Gezelius et al. (1973) showed that large amounts of PolyP
were synthesized during the transition of Dictyostelium discoideum from the amoeboid to
the aggregated stage.
All these data suggested that PolyPs are very important for the development of fungi,
especially spore formation and germination. Tables 8.4–8.6 and Figures 8.27 and 8.28 show
the changes in PolyP content at different stages of development in some fungi.
Under vegetative growth, fungal cells, like yeast cells, possess PolyPs of different chain
lengths, belonging to acid-soluble, salt-soluble, alkali-soluble and acid-insoluble fractions
and which are localized in different cell compartments. PolyPs were found in the vacuoles,
cell envelope and nuclei of fungi (see Chapter 5). The dynamics of the PolyP content in
three different strains of N. crassa are illustrated in Figure 8.28. It can be seen that different
fractions of PolyP have individual changes during the culture growth. The slime variant
without the cell wall is characterized by the lower content of the most high-molecular-weight
fractions, while the mutant with the lower exopolyphosphatase activity is characterized by
the higher content of PolyP (Trilisenko et al., 1980, 1982a,b).

Table 8.4 PolyP content in the cells of Endomyces magnusii (Kulaev et al., 1967a), Neu-
rospora crassa (Kulaev et al., 1966a) and in the fruiting bodies of Giramitra esculenta
(Kulaev et al., 1960b), expressed as mg of P per g of dry biomass.
E. magnusii N. crassa G. esculenta
cells, 12 h mycelia, 17 h fruiting
PolyP fraction Extractant growth growth bodies
PolyP(I) 0.5 M HClO 4 , 0–4 C 1.10 0.62 0.00
◦
PolyP(II) Saturated NaClO 4 0.90 1.24 1.52
solution, 0–4 C
◦
◦
PolyP(III) NaOH, pH 9, 0–4 C 0.20 0.12 0.24
◦
PolyP(IV) NaOH, pH 12, 0–4 C 0.90 0.82 0.01
PolyP(V) 10 % HClO 4 , 100 C 0.40 0.00 —
◦
Total PolyP — 3.50 2.80 1.77
Total P — 17.3 15.6 6.03