beta-D-Man-(1->4)-beta-D-GlcA-(1->2)-alpha-D-Man-(1->3)-beta-D-Glc-(1->4)-alpha-D-Glc-di-trans,octa-cis-undecaprenyl diphosphate + phosphoenolpyruvate = 4,6-Me(COOH)C-beta-D-Man-(1->4)-beta-D-GlcA-(1->2)-alpha-D-Man-(1->3)-beta-D-Glc-(1->4)-alpha-D-Glc-di-trans,octa-cis-undecaprenyl diphosphate + phosphate — reaction