McIver C J, Tapsall J W
Department of Microbiology, Prince of Wales Hospital, Sydney, NSW, Australia.
J Med Microbiol. 1993 Nov;39(5):382-7. doi: 10.1099/00222615-39-5-382.
Cysteine-dependent (cys-) Escherichia coli and Klebsiella spp., defective in sulphate assimilation, were isolated from urine and stool samples of infected patients. These isolates reverted to prototrophy under conditions of cysteine deprivation but the revertant strains and a prototrophic wild-type E. coli strain became auxotrophic for cysteine in a cysteine-enriched medium. This suggested that excess cysteine acts as a repressor of the cys HIJ operon known to control aspects of cysteine biosynthesis. A group of mostly elderly patients infected with cys- strains suffered a disproportionate amount of renal impairment as compared with a control group. In renal impairment, sulphur compounds, including cysteine, are retained. This raises the possibility that these raised levels of cysteine and related compounds may enhance the selection of cys- strains in vivo.
从感染患者的尿液和粪便样本中分离出了在硫酸盐同化方面存在缺陷的半胱氨酸依赖性（cys-）大肠杆菌和克雷伯氏菌属。这些分离株在半胱氨酸缺乏的条件下恢复为原养型，但回复菌株和原养型野生型大肠杆菌菌株在富含半胱氨酸的培养基中对半胱氨酸变为营养缺陷型。这表明过量的半胱氨酸作为已知控制半胱氨酸生物合成某些方面的cys HIJ操纵子的阻遏物。与对照组相比，一组主要感染cys-菌株的老年患者肾功能损害的比例过高。在肾功能损害中，包括半胱氨酸在内的硫化合物会潴留。这增加了这些升高的半胱氨酸及相关化合物水平可能会在体内增强cys-菌株选择的可能性。
