Braun M L, Niederpruem D J
J Bacteriol. 1969 Nov;100(2):625-34. doi: 10.1128/jb.100.2.625-634.1969.
Erythritol uptake and metabolism were compared in wild-type mycelium and a dome morphological mutant of the wood-rotting mushroom Schizophyllum commune. Wild-type mycelium utilized glucose, certain hexitols, and pentitols including ribitol, as well as d-erythrose, erythritol, and glycerol as sole carbon sources for growth. The dome mutant utilized all of these compounds except d-erythrose and erythritol. Erythritol- or glycerol-grown wild-type mycelium incorporated erythritol into various cellular constituents, whereas glucose-grown cells lagged considerably before initiation of erythritol uptake. This acquisition was inhibited by cycloheximide. Dome mycelium showed behavior similar to wild-type in uptake of erythritol after growth on glucose or glycerol, except that erythritol was not further catabolized. Enzymes of carbohydrate metabolism were compared in cell extracts of glucose-cultured wild-type mycelium and dome. Enzymes of hexose monophosphate catabolism, nicotinamide adenine dinucleotide (NAD)-dependent sugar alcohol dehydrogenases, and reduced nicotinamide adenine dinucleotide phosphate (NADPH)-coupled erythrose reductase were demonstrated in both. The occurrence of erythrose reductase was unaffected by the nature of the growth carbon source, showed optimal activity at pH 7, and generated NAD phosphate and erythritol as products of the reaction. Glycerol-, d-erythrose-, or erythritol-grown wild-type mycelium contained an NAD-dependent erythritol dehydrogenase absent in glucose cells. Erythritol dehydrogenase activity was optimal at pH 8.8 and produced erythrulose during NAD reduction. Glycerol-growth of dome mycelium induced the erythritol uptake system, but a functional erythritol dehydrogenase could not be demonstrated. Neither wild-type nor dome mycelium produced erythritol dehydrogenase during growth on ribitol. Erythritol metabolism in wild-type cells of S. commune, therefore, involves an NADPH-dependent reduction of d-erythrose to produce erythritol, followed by induction of an NAD-coupled erythritol dehydrogenase to form erythrulose. A deficiency in erythritol dehydrogenase rather than permeability barriers explains why dome cannot employ erythritol as sole carbon source for mycelial growth.
在野生型菌丝体和木腐蘑菇裂褶菌的一种菌盖形态突变体中比较了赤藓糖醇的摄取和代谢情况。野生型菌丝体利用葡萄糖、某些己糖醇和戊糖醇（包括核糖醇），以及d - 赤藓糖、赤藓糖醇和甘油作为唯一碳源进行生长。菌盖突变体利用除d - 赤藓糖和赤藓糖醇之外的所有这些化合物。以赤藓糖醇或甘油培养的野生型菌丝体将赤藓糖醇掺入各种细胞成分中，而以葡萄糖培养的细胞在开始摄取赤藓糖醇之前有相当长的滞后时间。这种摄取受到环己酰亚胺的抑制。菌盖菌丝体在以葡萄糖或甘油生长后摄取赤藓糖醇时表现出与野生型相似的行为，只是赤藓糖醇不再进一步分解代谢。在葡萄糖培养的野生型菌丝体和菌盖的细胞提取物中比较了碳水化合物代谢酶。二者均显示出己糖单磷酸分解代谢酶、烟酰胺腺嘌呤二核苷酸（NAD）依赖性糖醇脱氢酶和还原型烟酰胺腺嘌呤二核苷酸磷酸（NADPH）偶联的赤藓糖还原酶。赤藓糖还原酶的存在不受生长碳源性质的影响，在pH 7时表现出最佳活性，并产生磷酸烟酰胺腺嘌呤二核苷酸和赤藓糖醇作为反应产物。以甘油、d - 赤藓糖或赤藓糖醇培养的野生型菌丝体含有葡萄糖细胞中不存在的NAD依赖性赤藓糖醇脱氢酶。赤藓糖醇脱氢酶活性在pH 8.8时最佳，在NAD还原过程中产生赤藓酮糖。菌盖菌丝体在甘油生长时诱导了赤藓糖醇摄取系统，但未检测到有功能的赤藓糖醇脱氢酶。在以核糖醇生长期间，野生型和菌盖菌丝体均未产生赤藓糖醇脱氢酶。因此，裂褶菌野生型细胞中的赤藓糖醇代谢涉及NADPH依赖性将d - 赤藓糖还原以产生赤藓糖醇，随后诱导NAD偶联的赤藓糖醇脱氢酶形成赤藓酮糖。赤藓糖醇脱氢酶的缺乏而非通透性障碍解释了为什么菌盖不能将赤藓糖醇用作菌丝体生长的唯一碳源。
