Functional analysis of GT61 glycosyltransferases from grass species in xylan substitutions.

Multiple rice GT61 members were demonstrated to be xylan arabinosyltransferases (XATs) mediating 3-O-arabinosylation of xylan and the functions of XATs and xylan 2-O-xylosyltransferases were shown to be conserved in grass species. Xylan is the major hemicellulose in the cell walls of grass species and it is typified by having arabinofuranosyl (Araf) substitutions. In this report, we demonstrated that four previously uncharacterized, Golgi-localized glycosyltransferases residing in clade A or B of the rice GT61 family were able to mediate 3-O-arabinosylation of xylan when heterologously expressed in the Arabidopsis gux1/2/3 triple mutant.