Sarvas M, Nikaido H
J Bacteriol. 1971 Mar;105(3):1063-72. doi: 10.1128/jb.105.3.1063-1072.1971.
The "T1 side chain" portion of cell wall lipopolysaccharide from T1 strains of Salmonella contains d-galactofuranose and d-ribofuranose residues. Isotope labeling studies, using intact cells of mutants each blocked at either of the two different steps of d-galactose metabolism (uridine diphosphate-glucose 4-epimerase and galactose-1-P uridylyl transferase) or at phosphoglucoisomerase, led to the following conclusions. (i) d-Galactofuranose residues are synthesized from d-galactopyranose or its derivatives, rather than by a direct conversion from other hexopyranoses or their derivatives. (ii) The pyranose-to-furanose conversion does not appear to take place at the level of the free d-galactose or d-galactose 1-phosphate. This result suggests that the conversion may occur at the stage of uridine diphosphate-d-galactose. (iii) In a mutant lacking phosphoglucoisomerase, d-ribofuranose residues in T1 side chains contained (14)C derived from exogenous d-fructose-U-(14)C, but little (3)H from exogenous d-glucose-1-(3)H. Thus, no evidence was found for a direct pathway of aldohexose-to-ribose conversion involving a loss of one of the carbons in the C2-C6 moiety of aldohexoses. This suggests, but does not prove, that the T1 ribofuranose residues are synthesized by conventional mechanisms involving hexose monophosphate shunt and transketolase-transaldolase reactions.
来自沙门氏菌T1菌株的细胞壁脂多糖的“T1侧链”部分含有D-半乳呋喃糖和D-核糖呋喃糖残基。利用在D-半乳糖代谢的两个不同步骤（尿苷二磷酸葡萄糖4-表异构酶和半乳糖-1-磷酸尿苷酰转移酶）或磷酸葡萄糖异构酶中任何一个步骤被阻断的突变体的完整细胞进行的同位素标记研究得出了以下结论。（i）D-半乳呋喃糖残基是由D-吡喃半乳糖或其衍生物合成的，而不是由其他己糖吡喃糖或其衍生物直接转化而来。（ii）吡喃糖到呋喃糖的转化似乎不是在游离D-半乳糖或D-半乳糖1-磷酸的水平上发生的。这一结果表明该转化可能发生在尿苷二磷酸-D-半乳糖阶段。（iii）在一个缺乏磷酸葡萄糖异构酶的突变体中，T1侧链中的D-核糖呋喃糖残基含有来自外源D-果糖-U-（14）C的（14）C，但来自外源D-葡萄糖-1-（3）H的（3）H很少。因此，没有发现醛己糖到核糖转化的直接途径涉及醛己糖C2-C6部分中一个碳原子的丢失的证据。这表明，但没有证明，T1核糖呋喃糖残基是通过涉及磷酸己糖旁路和转酮醇酶-转醛醇酶反应的传统机制合成的。
