GLYCOSYLATION OF THREONINE OF THE REPEATING UNIT OF RNA-POLYMERASE-IIWITH BETA-LINKED N-ACETYLGLUCOSAME LEADS TO A TURNLIKE STRUCTURE

Two models of the repeating C-terminal domain of RNA polymerase II (Ac -SYSPTSPSYS-NH2; Ac-SYSPT(beta-O-GlcNAc)SPSYS-NH2) were prepared and t heir conformations in water studied using 1-D and 2-D H-1 NMR spectros copies, CD spectrophotometry, fluorescence anisotropy, and molecular m echanics and dynamics calculations. The data suggest that glycosylatio n of the native, randomly coiled peptide with a single, biologically r elevant sugar leads to the formation of a turn. This report represents the first structural study of a new class of glycoproteins monoglycos ylated with N-acetylglucosamine on threonine.