Page 87 - The Biochemistry of Inorganic Polyphosphates

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Enzymes of polyphosphate biosynthesis 71
Table 6.2 Specific activities of 1,3-diphosphoglycerate–polyphosphate phos-
photransferase in some microorganisms (Kulaev et al., 1971).
1,3-Diphosphoglycerate–polyphosphate
phosphotransferase activity
Microorganism (mE per mg of protein)
Neurospora crassa (wild strain) 0.53
Neurospora crassa 1.45
(adenine-deficient mutant)
Penicillium chrysogenum 0.28
Propionibacterium schermanii 0.04
Micrococcus lysodeikticus 0.06
Escherichia coli 0.14
Actinomyces aureofaciens 0.05

O O CH
− – − – – − − – – 3 CH 3
– −
2 − −
– − – − CH 3
OH − P − O − P − O − CH CH 2 CHCH 2 − (CH 2 CH – CCH 2 ) 14–18 −CH 2 CH C −
O O
Figure 6.3 The structure of yeast dolichyl diphosphate.

Furthermore, this activity was found in a cell-free extract of the wild strain of N. crassa
and in other microorganisms including bacteria, but was much lower than in an adenine-
defficient N. crassa strain (Table 6.2). This pathway of PolyP synthesis probably occurs
during glycolytic phosphorylation under a low ATP content in the cell and might actually
be involved in the biosynthesis of some, presumably low-molecular-weight, PolyP frac-
tions. Some authors, however, believe that PolyP biosynthesis in the lower eucaryotes to
be apparently provided by 1,3-diphosphoglucerate:PolyP phosphotransferase (Schuddemat
et al., 1989a). This enzyme has not been purified and therefore needs further investigation.

6.1.3 Dolichyl-Diphosphate:Polyphosphate
Phosphotransferase (EC 2.7.4.20)

This enzyme’s activity was found in the membrane fraction of yeast cells (Shabalin et al.,
1979, 1985; Naumov et al., 1985; Kulaev et al., 1987; Shabalin and Kulaev, 1989), where
PolyP synthesis using β-phosphate groups of dolichyl diphosphate (Figure 6.3) took place:

dolichyl diphosphate + PolyP −−→ dolichyl phosphate + PolyP (6.8)
n n + 1
The enzyme was solubilized from the membrane fraction using Triton X-100 (Shabalin
and Kulaev, 1989). The specific activity of the solubilized preparation was 20 times higher
than that in protoplast lysate. The dolichyl-diphosphate:PolyP phosphotransferase activities
of the membrane preparation and solubilized fraction were etal-dependent and exhibited the
maximum activity in the presence of Mg 2+ or Ca . The same membrane fraction posessed
2+