Cheng H M, Aronson A I, Holt S C
J Bacteriol. 1973 Mar;113(3):1134-43. doi: 10.1128/jb.113.3.1134-1143.1973.
There is a marked increase in the half-cystine content of bacterial spores, especially the coat layers at the time of formation of the outer coat. When a cysteine auxotroph of Bacillus cereus T is grown on limiting cysteine, the spores contain the normal content of half-cystine, suggesting an alternate source. Glutathione appears to be such a supply of cysteine since it is hydrolyzed during sporulation and there are increased activities of the hydrolyzing enzymes at the same time. In addition, a cysteine auxotroph with a second alteration, a temperature-sensitive glutathione disulfide reductase, produces lysozyme-sensitive spores at 40 C. These spores appear to be defective in the formation of outer spore coat. During sporulation at 40 C, the double mutant accumulates oxidized glutathione which is a poor substrate for the hydrolytic enzymes. As a result, sporulating cells are deficient in half-cystines which are essential for outer spore coat morphogenesis. This alteration can be overcome by a shift to 30 C or by addition of cystinyl-pencillamine or cysteinyl-glycine to cultures sporulating at 40 C.
细菌芽孢中半胱氨酸含量显著增加，尤其是在形成外孢壁时的孢壁层。当蜡样芽孢杆菌T的半胱氨酸营养缺陷型在限量半胱氨酸条件下生长时，芽孢中的半胱氨酸含量正常，这表明存在替代来源。谷胱甘肽似乎是半胱氨酸的一种供应源，因为它在孢子形成过程中被水解，同时水解酶的活性增加。此外，具有第二种改变（温度敏感型谷胱甘肽二硫化物还原酶）的半胱氨酸营养缺陷型在40℃时产生对溶菌酶敏感的芽孢。这些芽孢在外孢壁形成方面似乎存在缺陷。在40℃进行孢子形成时，双突变体积累氧化型谷胱甘肽，而氧化型谷胱甘肽是水解酶的不良底物。结果，正在进行孢子形成的细胞缺乏外孢壁形态发生所必需的半胱氨酸。这种改变可以通过转移到30℃或向在40℃进行孢子形成的培养物中添加胱氨酰青霉胺或半胱氨酰甘氨酸来克服。
