Chen G S, Metzenberg R L
Genetics. 1974 Aug;77(4):627-38. doi: 10.1093/genetics/77.4.627.
Mutants resistant to selenomethionine were isolated, and their properties studied. Mapping studies indicate that the mutation sites are located near the eth-1(r) locus in linkage group I, about ten map units away from the mating type locus. The sites of new mutation are either allelic to or very close to eth-1(r). They are resistant not only to selenomethionine but also to ethionine, while the ethionine-resistant mutant, eth-1(r), is sensitive to selenomethionine. The selenomethionine-resistant mutants are also temperature-sensitive mutants. However, they can grow at higher temperatures in medium containing 1 M glycerol.-It is very unlikely that the resistance is due to a change in the permeability of the membrane. Aryl sulfatase of se-met(r) mutants is not repressed by a high concentration of methionine (5 mM), although inorganic sulfate (2 mM) still can cause total repression. The gamma-cystathionase levels of the mutants are normal, but the S-adenosylmethionine synthetase levels are only one-tenth of that observed in the wild-type strain. The heat-stability of this enzyme in the mutant is also different from that of the wild-type enzyme suggesting that the mutation might affect the structural gene of S-adenosylmethionine synthetase.
分离出了对硒代蛋氨酸具有抗性的突变体，并对其特性进行了研究。定位研究表明，突变位点位于连锁群I中的eth-1(r)基因座附近，距离交配型基因座约10个图距单位。新突变的位点要么与eth-1(r)等位，要么与之非常接近。它们不仅对硒代蛋氨酸有抗性，而且对乙硫氨酸也有抗性，而抗乙硫氨酸的突变体eth-1(r)对硒代蛋氨酸敏感。抗硒代蛋氨酸的突变体也是温度敏感型突变体。然而，它们在含有1 M甘油的培养基中能在较高温度下生长。抗性不太可能是由于膜通透性的改变。se-met(r)突变体的芳基硫酸酯酶不受高浓度蛋氨酸（5 mM）的抑制，尽管无机硫酸盐（2 mM）仍能导致完全抑制。突变体的γ-胱硫醚酶水平正常，但S-腺苷甲硫氨酸合成酶水平仅为野生型菌株中观察到的水平的十分之一。该酶在突变体中的热稳定性也与野生型酶不同，这表明突变可能影响了S-腺苷甲硫氨酸合成酶的结构基因。
