Page 156 - The Biochemistry of Inorganic Polyphosphates

WU095/Kulaev
WU095-08
Peculiarities of polyphosphate metabolism
140 March 9, 2004 20:32 Char Count= 0
Table 8.1 The content of P i and PolyPs in the early stationary growth phase
in Halobacterium salinarium and Halorubrum distributum (µmol of P i per g
of wet biomass).
Initial P i concentration in medium
H. salinarium H. distributum

Component 2.3 mM 11.5 mM 2.3 mM 11.5 mM

170 1000 100 760
P i
Acid-soluble PolyP 30 100 30 90
Alkali-soluble PolyP 9 4 5 8
Acid-insoluble PolyP 1 1 0.7 1.2

in this bacterium differ little in the light and in the dark. However, under conditions of
phototrophic nutrition, the ratio of salt-soluble to total PolyPs in the cells at all stages of
growth was much higher than in the control cells grown in the dark.
These data are in good agreement with the investigations on the purple bacteria carried
out by Weber (1965). However, Rh. rubrum and Rhodospheromonas spheroides differed
substantially in PolyP distribution between variuos fractions. In Rh. rubrum, the greater
part of PolyP was found in the acid-insoluble fraction, whereas in Rhodospheromonas
spheroides the acid-soluble PolyPs constituted a much greater part of the total content in the
cells. PolyPs were also identified in other photosynthesizing bacteria, namely Chromatium
okenii (Schlegel, 1962), and Rhodopseudomonas palustris (Fedorov, 1961).
As to the enzymes of PolyP metabolism in photosynthetic bacteria, polyphosphate kinase
activity was revealed in the cyanobacteria Anacystis nidulans (Vaillancourt et al., 1978) and
Oscillatoria redekei (Zaiss, 1985). The mutant in this enzyme had no PolyP granules ob-
servable by electron microscopy (Vaillancourt et al., 1978). The alignment analysis revealed
the genes encoding putative polyphosphate kinase ( ppk1 and ppk2) in several genomes of
cyanobacteria (Zhang et al., 2002) (see Table 6.1 above).
The cyanobacterium Synechocystis sp possesses the ppx gene encoding exopolyphos-
phatase, which was induced by P i starvation. The ppx mutant exhibited lower growth rates
under P i -sufficient conditions, hence indicating the importance of exopolyphosphatase in
the phosphorus metabolism of this organism (Gomez-Garcia et al., 2003).

8.7 Mycobacteria and Corynebacteria

The metabolism of PolyP in these two genera of bacteria has many features in common, and
it would be better to discuss them together. These bacteria, under normal growth conditions,
accumulate substantial amounts of volutin granules and possess the widest range of PolyP-
metabolizing enzymes known so far (Muhammed et al., 1959; Muhammed, 1961; Hughes
and Muhammed, 1962; Szymona, 1957, 1962, 1964; Phillips et al., 1999).
The most detailed investigations into PolyP metabolism of the Mycobacteria and
Corynebacteria have been carried out by Drews (1960a,b), Mudd and co-workers (Mudd