Cyclic organization of the carbohydrate metabolism in Sinorhizobium meliloti
J C Portais1, P Tavernier, I Gosselin
1Laboratoire de Génie Cellulaire, UPRES-A CNRS 6022, Faculté des Sciences, Université de Picardie Jules Verne, Amiens, France. Jean-Charles.Portais@sc.u-picardie.fr
Abstract:
The pathways of polysaccharide biosynthesis were investigated in cells of Sinorhizobium meliloti (strain Su47) using a stable isotope approach. The isotopic labeling of the periplasmic beta-1,2-glucans synthesized from glucose labeled at various positions evidenced the involvement of catabolic pathways, namely the pentose-phosphate and Entner-Doudoroff pathways, into the early steps of polysaccharide synthesis. The exopolysaccharides produced at the same time had a labeling pattern similar to that of the beta-glucans, indicating similar early steps for both polysaccharides. The results emphasized a cyclic organization of the carbohydrate metabolism in S. meliloti, in which the carbons of the initial hexose were allowed to re-enter the catabolic pathways many times. The metabolic incidences of such metabolic topology are discussed.
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