Is likely the initiating enzyme for the K2 capsular polysaccharide synthesis. Catalyzes the transfer of the glucose-1-phosphate moiety from UDP-Glc onto the carrier lipid undecaprenyl phosphate (C55-P), forming a phosphoanhydride bond yielding to glucosyl-pyrophosphoryl-undecaprenol (Glc-PP-C55) (By similarity). di-trans,octa-cis-undecaprenyl phosphate + UDP-alpha-D-glucose = alpha-D-glucosyl di-trans,octa-cis-undecaprenyl diphosphate + UMP Capsule biogenesis; capsule polysaccharide biosynthesis. Belongs to the bacterial sugar transferase family.