Rushlow K E, Deutch A H, Smith C J
Gene. 1985;39(1):109-12. doi: 10.1016/0378-1119(85)90115-5.
A 1.75-kb DNA fragment containing the entire Escherichia coli proB+ gene has been sequenced. The proB locus encodes the structural gene for gamma-glutamyl kinase (GK), the enzyme responsible for the first step in proline biosynthesis, and the primary regulatory point of the pathway. We have previously reported the nucleotide (nt) sequence of a mutant proB gene isolated from an E. coli strain resistant to the toxic analog of proline, 3,4-dehydro-DL-proline (DHP). This mutant gene encodes a GK which is refractory to allosteric feedback inhibition by proline (DHPR). Comparison of the proB+ and DHPR proB sequences revealed a single base difference, an A-T to C-G transversion localized at nt position 428 within the amino acid (aa) coding region of proB. This mutation predicts an aa change from glutamic acid in the wild-type (wt) enzyme to alanine in the DHPR enzyme.
一个包含完整大肠杆菌proB⁺基因的1.75千碱基对（kb）DNA片段已被测序。proB位点编码γ-谷氨酰激酶（GK）的结构基因，该酶是脯氨酸生物合成第一步的负责酶，也是该途径的主要调控点。我们之前报道了从一株对脯氨酸的毒性类似物3,4-脱氢-DL-脯氨酸（DHP）具有抗性的大肠杆菌菌株中分离出的突变proB基因的核苷酸（nt）序列。这个突变基因编码一种对脯氨酸（DHPR）的变构反馈抑制具有抗性的GK。proB⁺和DHPR proB序列的比较揭示了一个单碱基差异，即位于proB氨基酸（aa）编码区域内第428位核苷酸处的A-T到C-G的颠换。这个突变预测了从野生型（wt）酶中的谷氨酸到DHPR酶中的丙氨酸的氨基酸变化。
