Characterization of the biosynthesis of beta(1-2) cyclic glucan in R. Fredii. Beta(1-2) glucan has no apparent role in nodule invasion of Mc Call and Peking soybean cultivars.

• Autores: Iñón de Iannino, N.; Briones, G.; Kreiman, G.; Ugalde, R.
• Año de publicación: 1996
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Cell. Mol. Biol. (Noisy-le-grand) 1996;42(5):617-629
• Materia: bacterial protein; beta glucan; cyclic beta(1 2)glucan; cyclic beta(1-2)glucan; glucan; glycopeptide; membrane protein; uridine diphosphate glucose; article; biosynthesis; chemical structure; chemistry; classification; comparative study; electron microscopy; isolation and purification; kinetics; metabolism; microbiology; molecular weight; Rhizobium; soybean; species difference; symbiosis; ultrastructure; Bacterial Proteins; beta-Glucans; Glucans; Glycopeptides; Kinetics; Membrane Proteins; Microscopy, Electron; Molecular Structure; Molecular Weight; Rhizobium; Soybeans; Species Specificity; Symbiosis; Uridine Diphosphate Glucose
• Institución: Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales

Three wild type strains of Rhizobium fredii, USDA 191, USDA 257 and HH 303, do not synthesize in vivo or in vitro beta(1-3), beta(1-6) cyclic glucans, all strains form in vitro and in vivo cyclic beta(1-2) glucans. Approximately 80% of the recovered R. fredii cellular cyclic beta(1-2) glucans were anionic and the substituent was identified as phosphoglycerol. Inner membranes prepared from these R. fredii strains have a beta(1-2) glucan-intermediate-protein with apparent molecular mass undistinguishable from Agrobacterium tumefaciens beta(1-2) glucan intermediate protein. Studies of the degree of polymerization of the oligosaccharides recovered from the protein-intermediate after short pulse incubations with UDP-14C-glucose suggested that the rate limiting step in the biosynthesis of cyclic glucan is cyclization. Kinetic studies revealed that the K(m) for UDP-glucose was 0.33 mM. No difference was detected between the K(m) for initiation/elongation and cyclization reactions. Nodulation studies of a ndvB R. fredii mutant with Mc Call and Peking soybean cultivars, revealed that beta(1-2) glucans do not seem to be required for normal nodule invasion of these soybean cultivars.
Fil:Ugalde, R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.