Order of enzymic incorporation of O-methyl groups into the O-methyl-D-glucose-containing polysaccharide of Mycobacterium smegmatis. A tritium-labelling study.
The order of enzymic incorporation of O-methyl groups into the O-methyl-D-glucose-containing polysaccharide (MGP) of Mycobacterium smegmatis, 3MG(J)----G(I)----G(H) ----G(G)----6MG(F)----(GMG)9(E)----[G(L)----G(D)]----G(C) ----[G(K)----G(B)]----G(A)----Ga, where G is D-glucose, 3MG is 3-O-methyl-D-glucose, 6MG is 6-O-methyl-D-glucose, and Ga is D-glyceric acid, was studied by incubating cultures of M. smegmatis with L-[3H-Me]methionine for various times. MGP was then extracted from the cells, and relative radioactivities of residues D, (E + F)average and J, or of D, E average, F, and J, were determined. Tritium-labelling of these residues increased in the reducing-to-nonreducing residue direction, the steepness of the gradient becoming more shallow with increasing incubation time. The results are consistent with a biosynthetic mechanism that involves sequential addition of O-methyl groups to residues of the pre-formed D-glucan, in the reducing-to-nonreducing residue direction.
Walton
D J
DJ
Department of Biochemistry, Queen's University, Kingston, Ontario.
Jordan
D D
DD
D019325:3-O-Methylglucose; D002240:Carbohydrate Sequence; D002250:Carbon Radioisotopes; D008745:Methylation; D008757:Methylglucosides / Q000378:metabolism*; D008759:Methylglycosides / Q000378:metabolism*; D008969:Molecular Sequence Data; D009161:Mycobacterium / Q000378:metabolism*; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D014312:Trisaccharides / Q000378:metabolism; D014316:Tritium
D002250:Carbon Radioisotopes; D008757:Methylglucosides; D008759:Methylglycosides; D011135:Polysaccharides, Bacterial; D014312:Trisaccharides; D014316:Tritium; D019325:3-O-Methylglucose; C033884:6-O-methylglucose