Biosynthesis of pentose in Escherichia coli. Synthesis of deoxyribose in cells infected with bacteriophage.

The biosynthesis of ribose and deoxyribose in Escherichia coli involves both the oxidative pathway through 6-phosphogluconate and the nonoxidative pathway through the transketolase and transaldolase sequence (Lanning and Cohen, 1954; Bernstein, 1956; Bagatell, Wright, and Sable, 1959). The proportions of the oxidative and nonoxidative pathways depend on the nature of the principal carbon source in the medium, on the stage of growth of the culture, and on the previous history of the culture (Szynkiewicz, Sable, and Pflueger, 1961). In addition evidence has been presented that ribose and deoxyribose have a common origin in this organism (Bernstein and Sweet, 1958; Bagatell et al., 1959). Two studies (Lanning and Cohen, 1955; Loeb and Cohen, 1959) suggest that in bacteriophage-infected E. coli the nonoxidative pathway becomes of greater importance. The studies reported here support the view that both pathways are of considerable importance in the biosynthesis of deoxyribose in the presence of bacteriophage infection. Racker (1952) found an aldolase in E. coli that catalyzes the reversible reaction: