GlcA-beta-(1-2)-D-Man-alpha-(1-3)-D-Glc-beta-(1-4)-D-Glc-alpha-1-diphospho-ditrans,octacis-undecaprenol 4-beta-mannosyltransferase

GlcA-beta-(1->2)-D-Man-alpha-(1->3)-D-Glc-beta-(1->4)-D-Glc-alpha-1-diphospho-ditrans,octacis-undecaprenol 4-beta-mannosyltransferase (, GumI) is an enzyme with systematic name GDP-mannose:GlcA-beta-(1->2)-D-Man-alpha-(1->3)-D-Glc-beta-(1->4)-D-Glc-alpha-1-diphospho-ditrans,octacis-undecaprenol 4-beta-mannosyltransferase. This enzyme catalyses the following chemical reaction


 * GDP-mannose + GlcA-beta-(1->2)-D-Man-alpha-(1->3)-D-Glc-beta-(1->4)-D-Glc-alpha-1-diphospho-ditrans,octacis-undecaprenol $$\rightleftharpoons$$ GDP + D-Man-beta-(1->4)- GlcA-beta-(1->2)-D-Man-alpha-(1->3)-D-Glc-beta-(1->4)-D-Glc-alpha-1-diphospho-ditrans,octacis-undecaprenol

The enzyme is involved in the biosynthesis of the exopolysaccharide xanthan.