Pathways and key enzymes targeted for the development ofB. suisvaccines. Schematic representation of Brucella (A) LPS biosynthesis steps that occur at both sides of the inner membrane (IM), B LPS core, and C central carbon metabolism. The proteins corresponding to the mutants investigated are indicated with arrows. WbkF, bactoprenol (BctPP, Bactoprenol-P-P) primase for O-chain polymerization; Wzm/Wzt, O-chain translocation ABC transport system; WadA, core glycosyltransferase that incorporates the terminal glucose (Glc) linking the core to the two O-chain mannoses (Man) of the proximal section of the N-formyl-perosamine (NF-per) polysaccharide; Pgm, phosphoglucomutase necessary for the synthesis of the UPD-glucose used by WadA; WadB, WadC and WadD, glycosyltransferases involved in the incorporation of glucosamine (GlcN) and Man to the core-lateral branch; Kdo, 3-deoxy-d-manno-octulosonic acid; Quin, quinovosamine. WboA, WboB, WbkA and WbkE, O-chain glycosyltransferases. F1,6bP, fructose-1,6-bisphosphate; DHAP, dihydroxyacetone-phosphate; GAP, glyceraldehyde-3-phosphate; PEP, phosphoenolpyruvate; PYR, pyruvate; AcCoA, acetyl-CoA; PckA, phosphoenolpyruvate carboxykinase; PpdK, pyruvate phosphate dikinase; EDP, Entner–Doudoroff pathway; PPP, pentose phosphate pathway; TCA, tricarboxylic acid cycle; GC, glyoxylate bypass. Asterisks mark substrates in the mGSM. The functionality of pathways represented as discontinuous lines varies depending on the Brucella species and biovar [17, 29,30,31,32,33,34, 56].