The mnn2 mutant of Saccharomyces cerevisiae is affected in phosphorylation of N-linked oligosaccharides.
We studied the phosphorylation of the inner core region of N-linked oligosaccharides in the mannan defective mutant Saccharomyces cerevisiae mnn2 which was described as unable to synthesize branches on the outer chain. We performed structural studies of the N-oligosaccharides synthesized by the strains mnn2, mnn1mnn2mnn9 and mnn1mnn9ldb8, and the results are compared with previously published structural data of mnn1mnn2mnn10 and mnn1mnn9 [Hernández, L.M., Ballou, L., Alvarado, E., Tsai, P.-K. and Ballou, C.E. (1989) J. Biol. Chem. 264, 13648-13659]. We conclude that the mnn2/ldb8 mutation is responsible for the inhibition of incorporation of phosphate to mannose A(3) (see below), a particular phosphorylation site of the inner core, while phosphorylation at the other possible site (mannose C(1)) is allowed, although it is also reduced. *Phosphorylation sites in mnn1mnn9. (see structure below)
Olivero
I
I
Department of Microbiology, University of Extremadura, Badajoz, Spain.
Mañas
P
P
Hernández
L M
LM
D002240:Carbohydrate Sequence; D002852:Chromatography, Ion Exchange; D009682:Magnetic Resonance Spectroscopy; D008358:Mannose / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D009844:Oligosaccharides / Q000235:genetics*; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism
D009844:Oligosaccharides; D010710:Phosphates; D008358:Mannose