A. In Bacillus, based on the present report, UDP-Glc pyrophosphorylase (UDP-Glc PPase) converts Glc-1-P and UTP to UDP-Glc. In the presence of NAD+, UDP-Glc is interconverted by UDP-glucose dehydrogenase (UGlcDH) into UDP-GlcA and NADH. UDP-GlcA can then be interconverted by the 4-epimerase, UGlcAE, into UDP-GalA.
B. Organization of the three genes within the UGalA operon and the flanking regions across selective members of Bacillus spp. The locus number for each gene in the operon across the different species shown is indicated. Based on this report, Bcer98_2076 functions as a UGlcDH and Bcer98_2077 as a UGlcAE. The operon also comprises a putative glycosyltransferase (Bcer98_2078 in B. cereus) which may be involved in the synthesis of GlcA or GalA-containing glycans. Note: except for Geobacillus sp. G11MC16, in the 5′ region flanking the UGalA operon there is a single gene in the opposite direction of the operon encoding a putative UDP-Glc PPase (Bcer98_2075 in B. cereus, putative ytdA in B. subtilis).