Kosuge T, Tabata K, Hoshino T
Institute of Applied Biochemistry, University of Tsukuba, Ibaraki, Japan.
FEMS Microbiol Lett. 1994 Oct 15;123(1-2):55-61. doi: 10.1111/j.1574-6968.1994.tb07201.x.
A 3.6 kb DNA fragment carrying the Thermus thermophilus proBA region, which encodes the first two steps in the proline biosynthetic pathway, was cloned from the Thermus thermophilus gene library, and its complete nucleotide sequence was determined. The deduced amino acid sequence of gamma-glutamyl kinase (40,657 Da), the product of proB gene, and gamma-glutamyl phosphate reductase (48,747 Da), the product of proA gene, showed 44.1% and 44.4% identity to those of Escherichia coli, respectively. The termination codon of the proB gene and the initiation codon of the proA gene overlapped by 2 bp. A possible transcriptional termination structure was found downstream of the proA gene but not downstream of the proB gene. These results indicate that the proBA genes of T. thermophilus form a single operon as in E. coli.
从嗜热栖热菌基因文库中克隆出一个携带嗜热栖热菌proBA区域的3.6 kb DNA片段，该区域编码脯氨酸生物合成途径的前两个步骤，并测定了其完整的核苷酸序列。proB基因产物γ-谷氨酰激酶（40,657 Da）和proA基因产物γ-谷氨酰磷酸还原酶（48,747 Da）的推导氨基酸序列与大肠杆菌的相应序列分别具有44.1%和44.4%的同一性。proB基因的终止密码子与proA基因的起始密码子重叠2个碱基对。在proA基因下游发现了一个可能的转录终止结构，但在proB基因下游未发现。这些结果表明，嗜热栖热菌的proBA基因如在大肠杆菌中一样形成一个单一的操纵子。
