Champney W S, Jensen R A
J Bacteriol. 1969 Apr;98(1):205-14. doi: 10.1128/jb.98.1.205-214.1969.
The d-isomer of tyrosine is a potent inhibitor of growth in transformable strain 168 of Bacillus subtilis. A d-tyrosine-resistant mutant of the inhibited strain was isolated which excreted l-tyrosine, had a diminished growth rate, and required l-phenylalanine to attain the growth rate of the wild-type parent. Mapping by deoxyribonucleate transformation located this resistance in the gene coding for prephenate dehydrogenase. This enzyme in the d-tyrosine-resistant mutant was insensitive to the usual feedback inhibition exerted by l-tyrosine in extracts of strain 168. In contrast, the growth of poorly transformable strain 23 of B. subtilis, as well as that of several other Bacillus species, was not affected by the analogue. Transformation mapping demonstrated no linkage of this latter "natural resistance" to several different aromatic markers. Prephenate dehydrogenase in extracts from strain 23 was as sensitive as that from strain 168 to feedback inhibition by l-tyrosine in vitro. The relationships of the latter results to the regulation of tyrosine biosynthesis and the possible nature of strain differences in d-tyrosine sensitivity are discussed.
酪氨酸的d-异构体是枯草芽孢杆菌可转化菌株168生长的强效抑制剂。从受抑制菌株中分离出了一株对d-酪氨酸具有抗性的突变体，该突变体分泌L-酪氨酸，生长速率降低，并且需要L-苯丙氨酸才能达到野生型亲本的生长速率。通过脱氧核糖核酸转化进行定位，发现这种抗性位于编码预苯酸脱氢酶的基因中。在对d-酪氨酸具有抗性的突变体中，这种酶对菌株168提取物中L-酪氨酸施加的常规反馈抑制不敏感。相比之下，枯草芽孢杆菌难转化菌株23以及其他几种芽孢杆菌属物种的生长不受该类似物的影响。转化定位表明，后一种“天然抗性”与几种不同的芳香族标记物没有连锁关系。在体外，菌株23提取物中的预苯酸脱氢酶与菌株168提取物中的预苯酸脱氢酶对L-酪氨酸反馈抑制的敏感性相同。本文讨论了后一种结果与酪氨酸生物合成调控的关系以及菌株对d-酪氨酸敏感性差异的可能性质。
