Lengeler J
Mol Gen Genet. 1980;179(1):49-54. doi: 10.1007/BF00268445.
From cultures of sensitive bacteria, treated with the antibiotic streptozotocin, two classes of resistant mutants can be isolated: 1) mutants, resistant under all the conditions tested to even the highest doses of the antibiotic. These are either pleiotropic-defective, pts-mutants, or more frequently, mutants lacking a transport system (enzyme IINag-complex of the PEP-dependent phosphotransferase system) encoded by the gene nagE. This gene is inducible by N-acetyl-glucosamine and seems to be part of the nag operon. The transport system in question is responsible for the uptake of N-acetyl-glucosamine, of D-glucosamine and of streptozotocin; 2) conditional resistant mutants which are unable to energize or to synthesize the streptozotocin transport system under certain growth conditions but do have the transport activity under other conditions. These include a) mutants auxotrophic for amino acids, vitamins, or nucleotides, b) mutants negative or sensitive to carbohydrates in the medium, and c) mutants wth defects in energy metabolism such as PEP synthesis.
从用抗生素链脲佐菌素处理的敏感细菌培养物中，可以分离出两类抗性突变体：1）在所有测试条件下，即使对抗生素的最高剂量也具有抗性的突变体。这些要么是多效缺陷型pts突变体，要么更常见的是缺乏由nagE基因编码的转运系统（磷酸烯醇式丙酮酸依赖性磷酸转移酶系统的酶IINag复合物）的突变体。该基因可被N-乙酰葡糖胺诱导，似乎是nag操纵子的一部分。所述转运系统负责N-乙酰葡糖胺、D-葡糖胺和链脲佐菌素的摄取；2）条件抗性突变体，它们在某些生长条件下无法为链脲佐菌素转运系统提供能量或合成该系统，但在其他条件下具有转运活性。这些包括：a）对氨基酸、维生素或核苷酸营养缺陷的突变体，b）对培养基中的碳水化合物呈阴性或敏感的突变体以及c）能量代谢存在缺陷（如磷酸烯醇式丙酮酸合成缺陷）的突变体。
