Wild J, Kłopotowski T
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warszawa, Poland.
Mol Gen Genet. 1975;136(1):63-73. doi: 10.1007/BF00275449.
It has been found that synthesis of D-amino acid dehydrogenase in Salmonella typhimurium is stimulated by cyclic AMP and crp gene product. This indicates that catabolic control of the dehydrogenase resembles other bacterial systems of catabolic repression. We have isolated S. typhimurium mutants, dadR, which are resistant to L-methionine-interference with D-histidine utilization and are able to utilize D-tryptophan as a precursor of L-tryptophan. Mapping data indicate that the dadR locus is closely linked to dadA coding for the structure of D-amino acid dehydrogenase. The synthesis of the dehydrogenase in dadR mutants is completely insensitive to the repression by glucose, but remains inducible by L-alanine. We conclude thereof that dadR mutants have changes in the promoter region which increase the expression of the dadA gene in the presence of glucose metabolism. A likely possibility that induction of the dad operon by alanine might be under positive control is discussed.
已发现鼠伤寒沙门氏菌中D-氨基酸脱氢酶的合成受环腺苷酸和crp基因产物的刺激。这表明脱氢酶的分解代谢控制类似于其他细菌的分解代谢阻遏系统。我们分离出了鼠伤寒沙门氏菌突变体dadR，它对L-甲硫氨酸干扰D-组氨酸利用具有抗性，并且能够利用D-色氨酸作为L-色氨酸的前体。定位数据表明，dadR位点与编码D-氨基酸脱氢酶结构的dadA紧密连锁。dadR突变体中脱氢酶的合成对葡萄糖的阻遏完全不敏感，但仍可被L-丙氨酸诱导。由此我们得出结论，dadR突变体的启动子区域发生了变化，在存在葡萄糖代谢的情况下增加了dadA基因的表达。还讨论了丙氨酸对dad操纵子的诱导可能受正调控的一种可能性。
