Biosynthesis of Cell Wall Lipopolysaccharide in Mutants of Salmonella V. A Mutant of Salmonella typhimurium Defective in the Synthesis of Cytidine Diphosphoabequose

摘要: A mutant of Salmonella typhimurium LT2 was found to be unable convert cytidine diphospho-4-keto-6-deoxy-d-glucose into diphosphoabequose. The mutation maps in the rfb gene cluster, which is known involved biosynthesis peripheral, “O side-chain” portion cell wall lipopolysaccharide. In spite fact that, O side chains, abequose not a part main chain but occurs as short branches, appears polymerize oligosaccharide “repeat units” long chains. following evidence indicates that this failure result absence diphosphoabequose rather than superimposed second other genes cluster. (i) does behave like multisite genetic crosses, and it gives rise, at high frequency, “revertants” where ability synthesize normal lipopolysaccharide with chains are both restored. (ii) strain has levels activity all enzymes side-chain synthesis, except several were lowered by about 30% owing polarity effect mutation. That lowering these responsible for clear from there revertants had regained some still enzymes, type revertant produced considerable amounts