||The bacterial phosphoenolpyruvate (PEP)-dependent group translocation system (PTS) requires the presence of both membrane-bound and cytoplasmic components to phosphorylate and translocate sugar. Deinococcus radiodurans has a functional fruA gene coding for the membrane-bound components of the fructose-specific PTS. However, fruB gene coding for the fructosespecific cytosolic components of PTS is a pseudogene. Yet, this bacterium metabolized fructose readily. In vitro studies showed that both cell membranes and cytoplasmic fractions of the cells were needed for fructose phosphorylation. Further studies showed that fructose phosphorylation required ATP, not PEP, as the phosphate donor. Unlike most PEP-dependent PTS systems, fructose phosphorylation is sensitive to sodium fluoride, a kinase inhibitor. Fructose phosphorylation was also inhibited in the presence of antiserum against a kinase phosphorylation site. |
During stationary phase, the highly radiation-resistant bacterium D. radiodurans undergoes new rounds of cell division when Mn2+ is added to the medium in a phenomenon known as manganese-induced cell division (MnCD). When cells were cultured in medium without Mn2+-enrichment, a proteinase K-resistant factor(s) with a molecular weight less than 10 kDa accumulated in the spent medium. Inclusion the concentrated spent medium to fresh medium could inhibit the growth of D. radiodurans significantly; and the degree of inhibition was dose dependent. However, the relative stimulatory effect of MnCD was also dose dependent—the higher the inhibition, the stronger the MnCD response.