Page 118 - The Biochemistry of Inorganic Polyphosphates

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Functions of polyphosphate and polyphosphate-dependent enzymes
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Figure 7.3 Model of a putative PolyP–PHB–Ca 2+ pump, indicating a hypothetical mechanism for
co-translocation of Ca 2+ and PolyP across the membrane (Reusch, 1992).

The next important property of PolyP–PHB complexes is their effect on DNA transfer
into bacterial cells. It was the striking correlation between PolyP–PHB concentrations and
transformation efficiencies in Azotobacter vinelandii, Bacillus subtilis and E. coli that led
Reusch and Sadoff (1988) to postulate that the complexes are involved in DNA transmem-
brane transport.
Nevertheless, it was found that, regardless of the method used to develop competence,
the result is a conspicuous increase in the concentration of the PolyP–PHB complexes
in the plasma membranes. When formation of the complexes is prevented by any means,
transformation is inhibited (Reusch et al., 1986; Huang and Reusch, 1995). DNA binding