Catalyzes the formation of UDP-glucuronic acid which is required for capsular polysaccharide synthesis. Does not catalyze the formation of glucuronamide moiety of the capsular polysaccharide. H2O + 2 NAD(+) + UDP-alpha-D-glucose = 3 H(+) + 2 NADH + UDP-alpha-D-glucuronate kcat is 1.2 sec(-1) with UDP-glucose as substrate. kcat is 0.80 sec(-1) with NAD(+) as substrate. Nucleotide-sugar biosynthesis; UDP-alpha-D-glucuronate biosynthesis; UDP-alpha-D-glucuronate from UDP-alpha-D-glucose: step 1/1. Capsule biogenesis; capsule polysaccharide biosynthesis. Homodimer. Belongs to the UDP-glucose/GDP-mannose dehydrogenase family.