Cyclic organization of the carbohydrate metabolism in Sinorhizobium meliloti.
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.
Portais
J C
JC
Laboratoire de Génie Cellulaire, UPRES-A CNRS 6022, Faculté des Sciences, Université de Picardie Jules Verne, Amiens, France. Jean-Charles.Portais@sc.u-picardie.fr
Tavernier
P
P
Gosselin
I
I
Barbotin
J N
JN
D050260:Carbohydrate Metabolism; D002247:Carbon Isotopes; D005936:Glucans / Q000096:biosynthesis*; D005947:Glucose / Q000378:metabolism; D008954:Models, Biological; D019906:Nuclear Magnetic Resonance, Biomolecular; D010427:Pentose Phosphate Pathway; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D016962:Sinorhizobium meliloti / Q000378:metabolism*; D047071:beta-Glucans
D002247:Carbon Isotopes; D005936:Glucans; D011135:Polysaccharides, Bacterial; D047071:beta-Glucans; C056779:succinoglycan; C033744:beta-1,2-glucan; D005947:Glucose