Function
Nonprocessive beta-mannosyltransferase that catalyzes the transfer of a mannose residue from GDP-mannose to glucuronic acid-beta-1,2-mannose-alpha-1,3-glucose-beta-1,4-glucose-PP-polyisoprenyl to form the lipid-linked pentasaccharide repeating unit of xanthan, Man-GlcA-Man-Glc(2)-PP-Pol. Is involved in the biosynthesis of the exopolysaccharide xanthan. To a lesser extent, can also use ADP-Man and even GDP-Glc as sugar donor substrates in vitro. Is unable to transfer a Man residue to the free-tetrasaccharide GlcA-Man-Glc(2) used as an acceptor, which indicates that the diphosphate group and the lipid moiety in the acceptor substrate are of major importance for acceptor binding and catalysis.
Sequence
MSASASLPVTRAAAAPRITVLFSTEKPNANTNPYLTQLYDALPDAVQPRFFSMREALLSRYDVLHLHWPEYLLRHPSKMGTLAKQACAALLLMKLQLTGTPVVRTLHNLAPHEDRGWRERALLRWIDQLTRRWIRINATTPVRPPFTDTILHGHYRDWFATMEQSTTLPGRLLHFGLIRPYKGVEVLLDVMRDVQDPRLSLRIVGNPATPXMRTLVETACAQDARISALLAYVEEPVLAREVSACELVVLPYKQMHNSGTLLLALSLARPVLAPWSESNAAIADEVGPGWVFLYEGEFDAALLSGMLDQVRAAPRGPAPDLSQRDWPRIGQLHYRTYLEALGKDGDAAL