Borgia P T, Gokul N K, Phillips G J
J Bacteriol. 1985 Dec;164(3):1049-56. doi: 10.1128/jb.164.3.1049-1056.1985.
A conditional developmental mutant of Mucor racemosus which is capable of oxidative energy metabolism is described. Unlike the wild-type strain the mutant was highly fermentative and exhibited the yeast morphology when grown aerobically in glucose-containing media. The high fermentative activity and yeast morphology under these conditions correlated well with maximal expression of glycolytic enzymes and with expression of some polypeptides characteristic of anaerobic growth. Aerobic growth of the mutant on amino acids as the sole carbon source resulted in growth in the mycelial morphology. The mutant was fully capable of oxidative metabolism as judged by its ability to grow on amino acids, respiratory capacity, and complement of tricarboxylic acid cycle enzymes. The results support the hypothesis that oxygen controls both the expression of glycolytic enzymes and the expression of proteins involved in morphogenesis. Moreover, they suggest that there are common regulatory elements in the control of these two classes of gene products. Abnormally high levels of aconitase and isocitrate dehydrogenase in the mutant are consistent with the proposal that pool sizes of citrate may act as a regulator of genes responsive to environmental oxygen concentration.
描述了一种总状毛霉的条件性发育突变体，它能够进行氧化能量代谢。与野生型菌株不同，该突变体具有高度发酵性，并且在含葡萄糖的培养基中需氧生长时呈现酵母形态。在这些条件下，高发酵活性和酵母形态与糖酵解酶的最大表达以及一些厌氧生长特征性多肽的表达密切相关。突变体以氨基酸作为唯一碳源进行需氧生长时，会呈现菌丝形态生长。从其在氨基酸上生长的能力、呼吸能力和三羧酸循环酶的组成来看，该突变体完全具备氧化代谢能力。这些结果支持了这样的假说，即氧气既控制糖酵解酶的表达，也控制参与形态发生的蛋白质的表达。此外，它们表明在这两类基因产物的控制中存在共同的调控元件。突变体中异常高水平的乌头酸酶和异柠檬酸脱氢酶与这样的观点一致，即柠檬酸的库大小可能作为对环境氧浓度作出反应的基因的调节因子。
