Page 167 - The Biochemistry of Inorganic Polyphosphates

March 9, 2004
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Yeast 151

Figure 8.16 Changes in the content of mannan (◦) and PolyP(IV) fraction (•) during growth of
Saccharomyces cerevisiae in a Reader medium in the presence (a) and absence (b) of a nitrogen
source (Kulaev et al., 1972d).

spectroscopic study showed that the logarithmic cells contained substantially shorter PolyPs
than the stationary cells (Greenfield et al., 1987).
The contents and chain lengths of the PolyPs in different fractions from S. cerevisiae
growing on a ‘Reader medium’ (Reader, 1927) with glucose and a sufficient amount of P i
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were studied by a combination of chemical extraction and P NMR spectroscopy (Vagabov
et al., 1998). Before glucose was consumed from the medium (11 h of culture growth), the
biomass and total cellular PolyP content had increased in parallel (Figure 8.17.). After
glucose depletion, the content of PolyP in the cells fell sharply and then increased again
in a 24 h culture. The significant decline in the content of intracellular PolyP, while the P i
concentration in the growth medium is high may imply that in this growth phase PolyP is
an energy rather than a P i source.
The changes in the contents of the PolyP(I) and PolyP(II) fractions were minimal during
yeast growth (Figure 8.17). The PolyP(III) fraction increased almost threefold after 3 h of
growth and then decreased by about fivefold by the time of glucose exhaustion (10.5 h of
culture growth). In contrast, the content of the PolyP(IV) fraction diminished noticeably
in a 3 h culture. It is known that the PolyP(IV) fraction is located at the peripheries of the
yeast cells and their synthesis is coupled with the synthesis of mannoproteins of the cell
wall (Shabalin et al., 1979, 1985). It can be assumed that the changes in the cellular content
of these PolyP fractions are associated with the formation of the cell wall in S. cerevisiae.
The PolyPs belonging to different fractions differ to a greater extent in their states
or localizations in the cells rather than in their degrees of polymerization (Vagabov
et al., 1998). The chain lengths of the PolyPs belonging to these fractions are not